From 244b2c5ca8b14627e4a17755e5922221e121c771 Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 09 Oct 2024 06:15:07 +0000
Subject: [PATCH] change system file
---
kernel/kernel/time/posix-cpu-timers.c | 1443 ++++++++++++++++++++++++++++++++-------------------------
1 files changed, 810 insertions(+), 633 deletions(-)
diff --git a/kernel/kernel/time/posix-cpu-timers.c b/kernel/kernel/time/posix-cpu-timers.c
index bfaa44a..bede1e6 100644
--- a/kernel/kernel/time/posix-cpu-timers.c
+++ b/kernel/kernel/time/posix-cpu-timers.c
@@ -20,11 +20,20 @@
static void posix_cpu_timer_rearm(struct k_itimer *timer);
+void posix_cputimers_group_init(struct posix_cputimers *pct, u64 cpu_limit)
+{
+ posix_cputimers_init(pct);
+ if (cpu_limit != RLIM_INFINITY) {
+ pct->bases[CPUCLOCK_PROF].nextevt = cpu_limit * NSEC_PER_SEC;
+ pct->timers_active = true;
+ }
+}
+
/*
* Called after updating RLIMIT_CPU to run cpu timer and update
- * tsk->signal->cputime_expires expiration cache if necessary. Needs
- * siglock protection since other code may update expiration cache as
- * well.
+ * tsk->signal->posix_cputimers.bases[clock].nextevt expiration cache if
+ * necessary. Needs siglock protection since other code may update the
+ * expiration cache as well.
*/
void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
{
@@ -35,46 +44,87 @@
spin_unlock_irq(&task->sighand->siglock);
}
-static int check_clock(const clockid_t which_clock)
+/*
+ * Functions for validating access to tasks.
+ */
+static struct pid *pid_for_clock(const clockid_t clock, bool gettime)
{
- int error = 0;
- struct task_struct *p;
- const pid_t pid = CPUCLOCK_PID(which_clock);
+ const bool thread = !!CPUCLOCK_PERTHREAD(clock);
+ const pid_t upid = CPUCLOCK_PID(clock);
+ struct pid *pid;
- if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
- return -EINVAL;
+ if (CPUCLOCK_WHICH(clock) >= CPUCLOCK_MAX)
+ return NULL;
- if (pid == 0)
- return 0;
+ /*
+ * If the encoded PID is 0, then the timer is targeted at current
+ * or the process to which current belongs.
+ */
+ if (upid == 0)
+ return thread ? task_pid(current) : task_tgid(current);
+
+ pid = find_vpid(upid);
+ if (!pid)
+ return NULL;
+
+ if (thread) {
+ struct task_struct *tsk = pid_task(pid, PIDTYPE_PID);
+ return (tsk && same_thread_group(tsk, current)) ? pid : NULL;
+ }
+
+ /*
+ * For clock_gettime(PROCESS) allow finding the process by
+ * with the pid of the current task. The code needs the tgid
+ * of the process so that pid_task(pid, PIDTYPE_TGID) can be
+ * used to find the process.
+ */
+ if (gettime && (pid == task_pid(current)))
+ return task_tgid(current);
+
+ /*
+ * For processes require that pid identifies a process.
+ */
+ return pid_has_task(pid, PIDTYPE_TGID) ? pid : NULL;
+}
+
+static inline int validate_clock_permissions(const clockid_t clock)
+{
+ int ret;
rcu_read_lock();
- p = find_task_by_vpid(pid);
- if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
- same_thread_group(p, current) : has_group_leader_pid(p))) {
- error = -EINVAL;
- }
+ ret = pid_for_clock(clock, false) ? 0 : -EINVAL;
rcu_read_unlock();
- return error;
+ return ret;
+}
+
+static inline enum pid_type clock_pid_type(const clockid_t clock)
+{
+ return CPUCLOCK_PERTHREAD(clock) ? PIDTYPE_PID : PIDTYPE_TGID;
+}
+
+static inline struct task_struct *cpu_timer_task_rcu(struct k_itimer *timer)
+{
+ return pid_task(timer->it.cpu.pid, clock_pid_type(timer->it_clock));
}
/*
* Update expiry time from increment, and increase overrun count,
* given the current clock sample.
*/
-static void bump_cpu_timer(struct k_itimer *timer, u64 now)
+static u64 bump_cpu_timer(struct k_itimer *timer, u64 now)
{
+ u64 delta, incr, expires = timer->it.cpu.node.expires;
int i;
- u64 delta, incr;
- if (timer->it.cpu.incr == 0)
- return;
+ if (!timer->it_interval)
+ return expires;
- if (now < timer->it.cpu.expires)
- return;
+ if (now < expires)
+ return expires;
- incr = timer->it.cpu.incr;
- delta = now + incr - timer->it.cpu.expires;
+ incr = timer->it_interval;
+ delta = now + incr - expires;
/* Don't use (incr*2 < delta), incr*2 might overflow. */
for (i = 0; incr < delta - incr; i++)
@@ -84,48 +134,26 @@
if (delta < incr)
continue;
- timer->it.cpu.expires += incr;
+ timer->it.cpu.node.expires += incr;
timer->it_overrun += 1LL << i;
delta -= incr;
}
+ return timer->it.cpu.node.expires;
}
-/**
- * task_cputime_zero - Check a task_cputime struct for all zero fields.
- *
- * @cputime: The struct to compare.
- *
- * Checks @cputime to see if all fields are zero. Returns true if all fields
- * are zero, false if any field is nonzero.
- */
-static inline int task_cputime_zero(const struct task_cputime *cputime)
+/* Check whether all cache entries contain U64_MAX, i.e. eternal expiry time */
+static inline bool expiry_cache_is_inactive(const struct posix_cputimers *pct)
{
- if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
- return 1;
- return 0;
-}
-
-static inline u64 prof_ticks(struct task_struct *p)
-{
- u64 utime, stime;
-
- task_cputime(p, &utime, &stime);
-
- return utime + stime;
-}
-static inline u64 virt_ticks(struct task_struct *p)
-{
- u64 utime, stime;
-
- task_cputime(p, &utime, &stime);
-
- return utime;
+ return !(~pct->bases[CPUCLOCK_PROF].nextevt |
+ ~pct->bases[CPUCLOCK_VIRT].nextevt |
+ ~pct->bases[CPUCLOCK_SCHED].nextevt);
}
static int
posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
{
- int error = check_clock(which_clock);
+ int error = validate_clock_permissions(which_clock);
+
if (!error) {
tp->tv_sec = 0;
tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
@@ -142,40 +170,64 @@
}
static int
-posix_cpu_clock_set(const clockid_t which_clock, const struct timespec64 *tp)
+posix_cpu_clock_set(const clockid_t clock, const struct timespec64 *tp)
{
+ int error = validate_clock_permissions(clock);
+
/*
* You can never reset a CPU clock, but we check for other errors
* in the call before failing with EPERM.
*/
- int error = check_clock(which_clock);
- if (error == 0) {
- error = -EPERM;
- }
- return error;
+ return error ? : -EPERM;
}
-
/*
- * Sample a per-thread clock for the given task.
+ * Sample a per-thread clock for the given task. clkid is validated.
*/
-static int cpu_clock_sample(const clockid_t which_clock,
- struct task_struct *p, u64 *sample)
+static u64 cpu_clock_sample(const clockid_t clkid, struct task_struct *p)
{
- switch (CPUCLOCK_WHICH(which_clock)) {
- default:
- return -EINVAL;
+ u64 utime, stime;
+
+ if (clkid == CPUCLOCK_SCHED)
+ return task_sched_runtime(p);
+
+ task_cputime(p, &utime, &stime);
+
+ switch (clkid) {
case CPUCLOCK_PROF:
- *sample = prof_ticks(p);
- break;
+ return utime + stime;
case CPUCLOCK_VIRT:
- *sample = virt_ticks(p);
- break;
- case CPUCLOCK_SCHED:
- *sample = task_sched_runtime(p);
- break;
+ return utime;
+ default:
+ WARN_ON_ONCE(1);
}
return 0;
+}
+
+static inline void store_samples(u64 *samples, u64 stime, u64 utime, u64 rtime)
+{
+ samples[CPUCLOCK_PROF] = stime + utime;
+ samples[CPUCLOCK_VIRT] = utime;
+ samples[CPUCLOCK_SCHED] = rtime;
+}
+
+static void task_sample_cputime(struct task_struct *p, u64 *samples)
+{
+ u64 stime, utime;
+
+ task_cputime(p, &utime, &stime);
+ store_samples(samples, stime, utime, p->se.sum_exec_runtime);
+}
+
+static void proc_sample_cputime_atomic(struct task_cputime_atomic *at,
+ u64 *samples)
+{
+ u64 stime, utime, rtime;
+
+ utime = atomic64_read(&at->utime);
+ stime = atomic64_read(&at->stime);
+ rtime = atomic64_read(&at->sum_exec_runtime);
+ store_samples(samples, stime, utime, rtime);
}
/*
@@ -193,29 +245,56 @@
}
}
-static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic, struct task_cputime *sum)
+static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic,
+ struct task_cputime *sum)
{
__update_gt_cputime(&cputime_atomic->utime, sum->utime);
__update_gt_cputime(&cputime_atomic->stime, sum->stime);
__update_gt_cputime(&cputime_atomic->sum_exec_runtime, sum->sum_exec_runtime);
}
-/* Sample task_cputime_atomic values in "atomic_timers", store results in "times". */
-static inline void sample_cputime_atomic(struct task_cputime *times,
- struct task_cputime_atomic *atomic_times)
-{
- times->utime = atomic64_read(&atomic_times->utime);
- times->stime = atomic64_read(&atomic_times->stime);
- times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime);
-}
-
-void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
+/**
+ * thread_group_sample_cputime - Sample cputime for a given task
+ * @tsk: Task for which cputime needs to be started
+ * @samples: Storage for time samples
+ *
+ * Called from sys_getitimer() to calculate the expiry time of an active
+ * timer. That means group cputime accounting is already active. Called
+ * with task sighand lock held.
+ *
+ * Updates @times with an uptodate sample of the thread group cputimes.
+ */
+void thread_group_sample_cputime(struct task_struct *tsk, u64 *samples)
{
struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
- struct task_cputime sum;
+ struct posix_cputimers *pct = &tsk->signal->posix_cputimers;
+
+ WARN_ON_ONCE(!pct->timers_active);
+
+ proc_sample_cputime_atomic(&cputimer->cputime_atomic, samples);
+}
+
+/**
+ * thread_group_start_cputime - Start cputime and return a sample
+ * @tsk: Task for which cputime needs to be started
+ * @samples: Storage for time samples
+ *
+ * The thread group cputime accouting is avoided when there are no posix
+ * CPU timers armed. Before starting a timer it's required to check whether
+ * the time accounting is active. If not, a full update of the atomic
+ * accounting store needs to be done and the accounting enabled.
+ *
+ * Updates @times with an uptodate sample of the thread group cputimes.
+ */
+static void thread_group_start_cputime(struct task_struct *tsk, u64 *samples)
+{
+ struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+ struct posix_cputimers *pct = &tsk->signal->posix_cputimers;
/* Check if cputimer isn't running. This is accessed without locking. */
- if (!READ_ONCE(cputimer->running)) {
+ if (!READ_ONCE(pct->timers_active)) {
+ struct task_cputime sum;
+
/*
* The POSIX timer interface allows for absolute time expiry
* values through the TIMER_ABSTIME flag, therefore we have
@@ -225,94 +304,70 @@
update_gt_cputime(&cputimer->cputime_atomic, &sum);
/*
- * We're setting cputimer->running without a lock. Ensure
- * this only gets written to in one operation. We set
- * running after update_gt_cputime() as a small optimization,
- * but barriers are not required because update_gt_cputime()
+ * We're setting timers_active without a lock. Ensure this
+ * only gets written to in one operation. We set it after
+ * update_gt_cputime() as a small optimization, but
+ * barriers are not required because update_gt_cputime()
* can handle concurrent updates.
*/
- WRITE_ONCE(cputimer->running, true);
+ WRITE_ONCE(pct->timers_active, true);
}
- sample_cputime_atomic(times, &cputimer->cputime_atomic);
+ proc_sample_cputime_atomic(&cputimer->cputime_atomic, samples);
+}
+
+static void __thread_group_cputime(struct task_struct *tsk, u64 *samples)
+{
+ struct task_cputime ct;
+
+ thread_group_cputime(tsk, &ct);
+ store_samples(samples, ct.stime, ct.utime, ct.sum_exec_runtime);
}
/*
- * Sample a process (thread group) clock for the given group_leader task.
- * Must be called with task sighand lock held for safe while_each_thread()
- * traversal.
+ * Sample a process (thread group) clock for the given task clkid. If the
+ * group's cputime accounting is already enabled, read the atomic
+ * store. Otherwise a full update is required. clkid is already validated.
*/
-static int cpu_clock_sample_group(const clockid_t which_clock,
- struct task_struct *p,
- u64 *sample)
+static u64 cpu_clock_sample_group(const clockid_t clkid, struct task_struct *p,
+ bool start)
{
- struct task_cputime cputime;
+ struct thread_group_cputimer *cputimer = &p->signal->cputimer;
+ struct posix_cputimers *pct = &p->signal->posix_cputimers;
+ u64 samples[CPUCLOCK_MAX];
- switch (CPUCLOCK_WHICH(which_clock)) {
- default:
- return -EINVAL;
- case CPUCLOCK_PROF:
- thread_group_cputime(p, &cputime);
- *sample = cputime.utime + cputime.stime;
- break;
- case CPUCLOCK_VIRT:
- thread_group_cputime(p, &cputime);
- *sample = cputime.utime;
- break;
- case CPUCLOCK_SCHED:
- thread_group_cputime(p, &cputime);
- *sample = cputime.sum_exec_runtime;
- break;
- }
- return 0;
-}
-
-static int posix_cpu_clock_get_task(struct task_struct *tsk,
- const clockid_t which_clock,
- struct timespec64 *tp)
-{
- int err = -EINVAL;
- u64 rtn;
-
- if (CPUCLOCK_PERTHREAD(which_clock)) {
- if (same_thread_group(tsk, current))
- err = cpu_clock_sample(which_clock, tsk, &rtn);
+ if (!READ_ONCE(pct->timers_active)) {
+ if (start)
+ thread_group_start_cputime(p, samples);
+ else
+ __thread_group_cputime(p, samples);
} else {
- if (tsk == current || thread_group_leader(tsk))
- err = cpu_clock_sample_group(which_clock, tsk, &rtn);
+ proc_sample_cputime_atomic(&cputimer->cputime_atomic, samples);
}
- if (!err)
- *tp = ns_to_timespec64(rtn);
-
- return err;
+ return samples[clkid];
}
-
-static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec64 *tp)
+static int posix_cpu_clock_get(const clockid_t clock, struct timespec64 *tp)
{
- const pid_t pid = CPUCLOCK_PID(which_clock);
- int err = -EINVAL;
+ const clockid_t clkid = CPUCLOCK_WHICH(clock);
+ struct task_struct *tsk;
+ u64 t;
- if (pid == 0) {
- /*
- * Special case constant value for our own clocks.
- * We don't have to do any lookup to find ourselves.
- */
- err = posix_cpu_clock_get_task(current, which_clock, tp);
- } else {
- /*
- * Find the given PID, and validate that the caller
- * should be able to see it.
- */
- struct task_struct *p;
- rcu_read_lock();
- p = find_task_by_vpid(pid);
- if (p)
- err = posix_cpu_clock_get_task(p, which_clock, tp);
+ rcu_read_lock();
+ tsk = pid_task(pid_for_clock(clock, true), clock_pid_type(clock));
+ if (!tsk) {
rcu_read_unlock();
+ return -EINVAL;
}
- return err;
+ if (CPUCLOCK_PERTHREAD(clock))
+ t = cpu_clock_sample(clkid, tsk);
+ else
+ t = cpu_clock_sample_group(clkid, tsk, false);
+ rcu_read_unlock();
+
+ *tp = ns_to_timespec64(t);
+ return 0;
}
/*
@@ -322,44 +377,32 @@
*/
static int posix_cpu_timer_create(struct k_itimer *new_timer)
{
- int ret = 0;
- const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
- struct task_struct *p;
-
- if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
- return -EINVAL;
-
- new_timer->kclock = &clock_posix_cpu;
-
- INIT_LIST_HEAD(&new_timer->it.cpu.entry);
+ static struct lock_class_key posix_cpu_timers_key;
+ struct pid *pid;
rcu_read_lock();
- if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
- if (pid == 0) {
- p = current;
- } else {
- p = find_task_by_vpid(pid);
- if (p && !same_thread_group(p, current))
- p = NULL;
- }
- } else {
- if (pid == 0) {
- p = current->group_leader;
- } else {
- p = find_task_by_vpid(pid);
- if (p && !has_group_leader_pid(p))
- p = NULL;
- }
+ pid = pid_for_clock(new_timer->it_clock, false);
+ if (!pid) {
+ rcu_read_unlock();
+ return -EINVAL;
}
- new_timer->it.cpu.task = p;
- if (p) {
- get_task_struct(p);
- } else {
- ret = -EINVAL;
- }
- rcu_read_unlock();
- return ret;
+ /*
+ * If posix timer expiry is handled in task work context then
+ * timer::it_lock can be taken without disabling interrupts as all
+ * other locking happens in task context. This requires a seperate
+ * lock class key otherwise regular posix timer expiry would record
+ * the lock class being taken in interrupt context and generate a
+ * false positive warning.
+ */
+ if (IS_ENABLED(CONFIG_POSIX_CPU_TIMERS_TASK_WORK))
+ lockdep_set_class(&new_timer->it_lock, &posix_cpu_timers_key);
+
+ new_timer->kclock = &clock_posix_cpu;
+ timerqueue_init(&new_timer->it.cpu.node);
+ new_timer->it.cpu.pid = get_pid(pid);
+ rcu_read_unlock();
+ return 0;
}
/*
@@ -370,13 +413,16 @@
*/
static int posix_cpu_timer_del(struct k_itimer *timer)
{
- int ret = 0;
- unsigned long flags;
+ struct cpu_timer *ctmr = &timer->it.cpu;
struct sighand_struct *sighand;
- struct task_struct *p = timer->it.cpu.task;
+ struct task_struct *p;
+ unsigned long flags;
+ int ret = 0;
- if (WARN_ON_ONCE(!p))
- return -EINVAL;
+ rcu_read_lock();
+ p = cpu_timer_task_rcu(timer);
+ if (!p)
+ goto out;
/*
* Protect against sighand release/switch in exit/exec and process/
@@ -385,44 +431,51 @@
sighand = lock_task_sighand(p, &flags);
if (unlikely(sighand == NULL)) {
/*
- * We raced with the reaping of the task.
- * The deletion should have cleared us off the list.
+ * This raced with the reaping of the task. The exit cleanup
+ * should have removed this timer from the timer queue.
*/
- WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry));
+ WARN_ON_ONCE(ctmr->head || timerqueue_node_queued(&ctmr->node));
} else {
if (timer->it.cpu.firing)
ret = TIMER_RETRY;
else
- list_del(&timer->it.cpu.entry);
+ cpu_timer_dequeue(ctmr);
unlock_task_sighand(p, &flags);
}
+out:
+ rcu_read_unlock();
if (!ret)
- put_task_struct(p);
+ put_pid(ctmr->pid);
return ret;
}
-static void cleanup_timers_list(struct list_head *head)
+static void cleanup_timerqueue(struct timerqueue_head *head)
{
- struct cpu_timer_list *timer, *next;
+ struct timerqueue_node *node;
+ struct cpu_timer *ctmr;
- list_for_each_entry_safe(timer, next, head, entry)
- list_del_init(&timer->entry);
+ while ((node = timerqueue_getnext(head))) {
+ timerqueue_del(head, node);
+ ctmr = container_of(node, struct cpu_timer, node);
+ ctmr->head = NULL;
+ }
}
/*
- * Clean out CPU timers still ticking when a thread exited. The task
- * pointer is cleared, and the expiry time is replaced with the residual
- * time for later timer_gettime calls to return.
+ * Clean out CPU timers which are still armed when a thread exits. The
+ * timers are only removed from the list. No other updates are done. The
+ * corresponding posix timers are still accessible, but cannot be rearmed.
+ *
* This must be called with the siglock held.
*/
-static void cleanup_timers(struct list_head *head)
+static void cleanup_timers(struct posix_cputimers *pct)
{
- cleanup_timers_list(head);
- cleanup_timers_list(++head);
- cleanup_timers_list(++head);
+ cleanup_timerqueue(&pct->bases[CPUCLOCK_PROF].tqhead);
+ cleanup_timerqueue(&pct->bases[CPUCLOCK_VIRT].tqhead);
+ cleanup_timerqueue(&pct->bases[CPUCLOCK_SCHED].tqhead);
}
/*
@@ -432,76 +485,45 @@
*/
void posix_cpu_timers_exit(struct task_struct *tsk)
{
- cleanup_timers(tsk->cpu_timers);
+ cleanup_timers(&tsk->posix_cputimers);
}
void posix_cpu_timers_exit_group(struct task_struct *tsk)
{
- cleanup_timers(tsk->signal->cpu_timers);
-}
-
-static inline int expires_gt(u64 expires, u64 new_exp)
-{
- return expires == 0 || expires > new_exp;
+ cleanup_timers(&tsk->signal->posix_cputimers);
}
/*
* Insert the timer on the appropriate list before any timers that
* expire later. This must be called with the sighand lock held.
*/
-static void arm_timer(struct k_itimer *timer)
+static void arm_timer(struct k_itimer *timer, struct task_struct *p)
{
- struct task_struct *p = timer->it.cpu.task;
- struct list_head *head, *listpos;
- struct task_cputime *cputime_expires;
- struct cpu_timer_list *const nt = &timer->it.cpu;
- struct cpu_timer_list *next;
+ int clkidx = CPUCLOCK_WHICH(timer->it_clock);
+ struct cpu_timer *ctmr = &timer->it.cpu;
+ u64 newexp = cpu_timer_getexpires(ctmr);
+ struct posix_cputimer_base *base;
- if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
- head = p->cpu_timers;
- cputime_expires = &p->cputime_expires;
- } else {
- head = p->signal->cpu_timers;
- cputime_expires = &p->signal->cputime_expires;
- }
- head += CPUCLOCK_WHICH(timer->it_clock);
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
+ base = p->posix_cputimers.bases + clkidx;
+ else
+ base = p->signal->posix_cputimers.bases + clkidx;
- listpos = head;
- list_for_each_entry(next, head, entry) {
- if (nt->expires < next->expires)
- break;
- listpos = &next->entry;
- }
- list_add(&nt->entry, listpos);
+ if (!cpu_timer_enqueue(&base->tqhead, ctmr))
+ return;
- if (listpos == head) {
- u64 exp = nt->expires;
+ /*
+ * We are the new earliest-expiring POSIX 1.b timer, hence
+ * need to update expiration cache. Take into account that
+ * for process timers we share expiration cache with itimers
+ * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
+ */
+ if (newexp < base->nextevt)
+ base->nextevt = newexp;
- /*
- * We are the new earliest-expiring POSIX 1.b timer, hence
- * need to update expiration cache. Take into account that
- * for process timers we share expiration cache with itimers
- * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
- */
-
- switch (CPUCLOCK_WHICH(timer->it_clock)) {
- case CPUCLOCK_PROF:
- if (expires_gt(cputime_expires->prof_exp, exp))
- cputime_expires->prof_exp = exp;
- break;
- case CPUCLOCK_VIRT:
- if (expires_gt(cputime_expires->virt_exp, exp))
- cputime_expires->virt_exp = exp;
- break;
- case CPUCLOCK_SCHED:
- if (expires_gt(cputime_expires->sched_exp, exp))
- cputime_expires->sched_exp = exp;
- break;
- }
- if (CPUCLOCK_PERTHREAD(timer->it_clock))
- tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
- else
- tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
- }
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
+ tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
+ else
+ tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
}
/*
@@ -509,24 +531,26 @@
*/
static void cpu_timer_fire(struct k_itimer *timer)
{
+ struct cpu_timer *ctmr = &timer->it.cpu;
+
if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
/*
* User don't want any signal.
*/
- timer->it.cpu.expires = 0;
+ cpu_timer_setexpires(ctmr, 0);
} else if (unlikely(timer->sigq == NULL)) {
/*
* This a special case for clock_nanosleep,
* not a normal timer from sys_timer_create.
*/
wake_up_process(timer->it_process);
- timer->it.cpu.expires = 0;
- } else if (timer->it.cpu.incr == 0) {
+ cpu_timer_setexpires(ctmr, 0);
+ } else if (!timer->it_interval) {
/*
* One-shot timer. Clear it as soon as it's fired.
*/
posix_timer_event(timer, 0);
- timer->it.cpu.expires = 0;
+ cpu_timer_setexpires(ctmr, 0);
} else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
/*
* The signal did not get queued because the signal
@@ -540,33 +564,6 @@
}
/*
- * Sample a process (thread group) timer for the given group_leader task.
- * Must be called with task sighand lock held for safe while_each_thread()
- * traversal.
- */
-static int cpu_timer_sample_group(const clockid_t which_clock,
- struct task_struct *p, u64 *sample)
-{
- struct task_cputime cputime;
-
- thread_group_cputimer(p, &cputime);
- switch (CPUCLOCK_WHICH(which_clock)) {
- default:
- return -EINVAL;
- case CPUCLOCK_PROF:
- *sample = cputime.utime + cputime.stime;
- break;
- case CPUCLOCK_VIRT:
- *sample = cputime.utime;
- break;
- case CPUCLOCK_SCHED:
- *sample = cputime.sum_exec_runtime;
- break;
- }
- return 0;
-}
-
-/*
* Guts of sys_timer_settime for CPU timers.
* This is called with the timer locked and interrupts disabled.
* If we return TIMER_RETRY, it's necessary to release the timer's lock
@@ -575,14 +572,24 @@
static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
struct itimerspec64 *new, struct itimerspec64 *old)
{
- unsigned long flags;
- struct sighand_struct *sighand;
- struct task_struct *p = timer->it.cpu.task;
+ clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
u64 old_expires, new_expires, old_incr, val;
- int ret;
+ struct cpu_timer *ctmr = &timer->it.cpu;
+ struct sighand_struct *sighand;
+ struct task_struct *p;
+ unsigned long flags;
+ int ret = 0;
- if (WARN_ON_ONCE(!p))
- return -EINVAL;
+ rcu_read_lock();
+ p = cpu_timer_task_rcu(timer);
+ if (!p) {
+ /*
+ * If p has just been reaped, we can no
+ * longer get any information about it at all.
+ */
+ rcu_read_unlock();
+ return -ESRCH;
+ }
/*
* Use the to_ktime conversion because that clamps the maximum
@@ -600,21 +607,22 @@
* longer get any information about it at all.
*/
if (unlikely(sighand == NULL)) {
+ rcu_read_unlock();
return -ESRCH;
}
/*
* Disarm any old timer after extracting its expiry time.
*/
+ old_incr = timer->it_interval;
+ old_expires = cpu_timer_getexpires(ctmr);
- ret = 0;
- old_incr = timer->it.cpu.incr;
- old_expires = timer->it.cpu.expires;
if (unlikely(timer->it.cpu.firing)) {
timer->it.cpu.firing = -1;
ret = TIMER_RETRY;
- } else
- list_del_init(&timer->it.cpu.entry);
+ } else {
+ cpu_timer_dequeue(ctmr);
+ }
/*
* We need to sample the current value to convert the new
@@ -624,11 +632,10 @@
* times (in arm_timer). With an absolute time, we must
* check if it's already passed. In short, we need a sample.
*/
- if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
- cpu_clock_sample(timer->it_clock, p, &val);
- } else {
- cpu_timer_sample_group(timer->it_clock, p, &val);
- }
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
+ val = cpu_clock_sample(clkid, p);
+ else
+ val = cpu_clock_sample_group(clkid, p, true);
if (old) {
if (old_expires == 0) {
@@ -636,18 +643,16 @@
old->it_value.tv_nsec = 0;
} else {
/*
- * Update the timer in case it has
- * overrun already. If it has,
- * we'll report it as having overrun
- * and with the next reloaded timer
- * already ticking, though we are
- * swallowing that pending
- * notification here to install the
- * new setting.
+ * Update the timer in case it has overrun already.
+ * If it has, we'll report it as having overrun and
+ * with the next reloaded timer already ticking,
+ * though we are swallowing that pending
+ * notification here to install the new setting.
*/
- bump_cpu_timer(timer, val);
- if (val < timer->it.cpu.expires) {
- old_expires = timer->it.cpu.expires - val;
+ u64 exp = bump_cpu_timer(timer, val);
+
+ if (val < exp) {
+ old_expires = exp - val;
old->it_value = ns_to_timespec64(old_expires);
} else {
old->it_value.tv_nsec = 1;
@@ -676,9 +681,9 @@
* For a timer with no notification action, we don't actually
* arm the timer (we'll just fake it for timer_gettime).
*/
- timer->it.cpu.expires = new_expires;
+ cpu_timer_setexpires(ctmr, new_expires);
if (new_expires != 0 && val < new_expires) {
- arm_timer(timer);
+ arm_timer(timer, p);
}
unlock_task_sighand(p, &flags);
@@ -686,8 +691,7 @@
* Install the new reload setting, and
* set up the signal and overrun bookkeeping.
*/
- timer->it.cpu.incr = timespec64_to_ns(&new->it_interval);
- timer->it_interval = ns_to_ktime(timer->it.cpu.incr);
+ timer->it_interval = timespec64_to_ktime(new->it_interval);
/*
* This acts as a modification timestamp for the timer,
@@ -710,6 +714,7 @@
ret = 0;
out:
+ rcu_read_unlock();
if (old)
old->it_interval = ns_to_timespec64(old_incr);
@@ -718,51 +723,34 @@
static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
{
- struct task_struct *p = timer->it.cpu.task;
- u64 now;
+ clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
+ struct cpu_timer *ctmr = &timer->it.cpu;
+ u64 now, expires = cpu_timer_getexpires(ctmr);
+ struct task_struct *p;
- if (WARN_ON_ONCE(!p))
- return;
+ rcu_read_lock();
+ p = cpu_timer_task_rcu(timer);
+ if (!p)
+ goto out;
/*
* Easy part: convert the reload time.
*/
- itp->it_interval = ns_to_timespec64(timer->it.cpu.incr);
+ itp->it_interval = ktime_to_timespec64(timer->it_interval);
- if (!timer->it.cpu.expires)
- return;
+ if (!expires)
+ goto out;
/*
* Sample the clock to take the difference with the expiry time.
*/
- if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
- cpu_clock_sample(timer->it_clock, p, &now);
- } else {
- struct sighand_struct *sighand;
- unsigned long flags;
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
+ now = cpu_clock_sample(clkid, p);
+ else
+ now = cpu_clock_sample_group(clkid, p, false);
- /*
- * Protect against sighand release/switch in exit/exec and
- * also make timer sampling safe if it ends up calling
- * thread_group_cputime().
- */
- sighand = lock_task_sighand(p, &flags);
- if (unlikely(sighand == NULL)) {
- /*
- * The process has been reaped.
- * We can't even collect a sample any more.
- * Call the timer disarmed, nothing else to do.
- */
- timer->it.cpu.expires = 0;
- return;
- } else {
- cpu_timer_sample_group(timer->it_clock, p, &now);
- unlock_task_sighand(p, &flags);
- }
- }
-
- if (now < timer->it.cpu.expires) {
- itp->it_value = ns_to_timespec64(timer->it.cpu.expires - now);
+ if (now < expires) {
+ itp->it_value = ns_to_timespec64(expires - now);
} else {
/*
* The timer should have expired already, but the firing
@@ -771,28 +759,48 @@
itp->it_value.tv_nsec = 1;
itp->it_value.tv_sec = 0;
}
+out:
+ rcu_read_unlock();
}
-static unsigned long long
-check_timers_list(struct list_head *timers,
- struct list_head *firing,
- unsigned long long curr)
+#define MAX_COLLECTED 20
+
+static u64 collect_timerqueue(struct timerqueue_head *head,
+ struct list_head *firing, u64 now)
{
- int maxfire = 20;
+ struct timerqueue_node *next;
+ int i = 0;
- while (!list_empty(timers)) {
- struct cpu_timer_list *t;
+ while ((next = timerqueue_getnext(head))) {
+ struct cpu_timer *ctmr;
+ u64 expires;
- t = list_first_entry(timers, struct cpu_timer_list, entry);
+ ctmr = container_of(next, struct cpu_timer, node);
+ expires = cpu_timer_getexpires(ctmr);
+ /* Limit the number of timers to expire at once */
+ if (++i == MAX_COLLECTED || now < expires)
+ return expires;
- if (!--maxfire || curr < t->expires)
- return t->expires;
-
- t->firing = 1;
- list_move_tail(&t->entry, firing);
+ ctmr->firing = 1;
+ /* See posix_cpu_timer_wait_running() */
+ rcu_assign_pointer(ctmr->handling, current);
+ cpu_timer_dequeue(ctmr);
+ list_add_tail(&ctmr->elist, firing);
}
- return 0;
+ return U64_MAX;
+}
+
+static void collect_posix_cputimers(struct posix_cputimers *pct, u64 *samples,
+ struct list_head *firing)
+{
+ struct posix_cputimer_base *base = pct->bases;
+ int i;
+
+ for (i = 0; i < CPUCLOCK_MAX; i++, base++) {
+ base->nextevt = collect_timerqueue(&base->tqhead, firing,
+ samples[i]);
+ }
}
static inline void check_dl_overrun(struct task_struct *tsk)
@@ -803,6 +811,20 @@
}
}
+static bool check_rlimit(u64 time, u64 limit, int signo, bool rt, bool hard)
+{
+ if (time < limit)
+ return false;
+
+ if (print_fatal_signals) {
+ pr_info("%s Watchdog Timeout (%s): %s[%d]\n",
+ rt ? "RT" : "CPU", hard ? "hard" : "soft",
+ current->comm, task_pid_nr(current));
+ }
+ __group_send_sig_info(signo, SEND_SIG_PRIV, current);
+ return true;
+}
+
/*
* Check for any per-thread CPU timers that have fired and move them off
* the tsk->cpu_timers[N] list onto the firing list. Here we update the
@@ -811,76 +833,50 @@
static void check_thread_timers(struct task_struct *tsk,
struct list_head *firing)
{
- struct list_head *timers = tsk->cpu_timers;
- struct task_cputime *tsk_expires = &tsk->cputime_expires;
- u64 expires;
+ struct posix_cputimers *pct = &tsk->posix_cputimers;
+ u64 samples[CPUCLOCK_MAX];
unsigned long soft;
if (dl_task(tsk))
check_dl_overrun(tsk);
- /*
- * If cputime_expires is zero, then there are no active
- * per thread CPU timers.
- */
- if (task_cputime_zero(&tsk->cputime_expires))
+ if (expiry_cache_is_inactive(pct))
return;
- expires = check_timers_list(timers, firing, prof_ticks(tsk));
- tsk_expires->prof_exp = expires;
-
- expires = check_timers_list(++timers, firing, virt_ticks(tsk));
- tsk_expires->virt_exp = expires;
-
- tsk_expires->sched_exp = check_timers_list(++timers, firing,
- tsk->se.sum_exec_runtime);
+ task_sample_cputime(tsk, samples);
+ collect_posix_cputimers(pct, samples, firing);
/*
* Check for the special case thread timers.
*/
soft = task_rlimit(tsk, RLIMIT_RTTIME);
if (soft != RLIM_INFINITY) {
+ /* Task RT timeout is accounted in jiffies. RTTIME is usec */
+ unsigned long rttime = tsk->rt.timeout * (USEC_PER_SEC / HZ);
unsigned long hard = task_rlimit_max(tsk, RLIMIT_RTTIME);
+ /* At the hard limit, send SIGKILL. No further action. */
if (hard != RLIM_INFINITY &&
- tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
- /*
- * At the hard limit, we just die.
- * No need to calculate anything else now.
- */
- if (print_fatal_signals) {
- pr_info("CPU Watchdog Timeout (hard): %s[%d]\n",
- tsk->comm, task_pid_nr(tsk));
- }
- __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
+ check_rlimit(rttime, hard, SIGKILL, true, true))
return;
- }
- if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
- /*
- * At the soft limit, send a SIGXCPU every second.
- */
- if (soft < hard) {
- soft += USEC_PER_SEC;
- tsk->signal->rlim[RLIMIT_RTTIME].rlim_cur =
- soft;
- }
- if (print_fatal_signals) {
- pr_info("RT Watchdog Timeout (soft): %s[%d]\n",
- tsk->comm, task_pid_nr(tsk));
- }
- __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
+
+ /* At the soft limit, send a SIGXCPU every second */
+ if (check_rlimit(rttime, soft, SIGXCPU, true, false)) {
+ soft += USEC_PER_SEC;
+ tsk->signal->rlim[RLIMIT_RTTIME].rlim_cur = soft;
}
}
- if (task_cputime_zero(tsk_expires))
+
+ if (expiry_cache_is_inactive(pct))
tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
}
static inline void stop_process_timers(struct signal_struct *sig)
{
- struct thread_group_cputimer *cputimer = &sig->cputimer;
+ struct posix_cputimers *pct = &sig->posix_cputimers;
- /* Turn off cputimer->running. This is done without locking. */
- WRITE_ONCE(cputimer->running, false);
+ /* Turn off the active flag. This is done without locking. */
+ WRITE_ONCE(pct->timers_active, false);
tick_dep_clear_signal(sig, TICK_DEP_BIT_POSIX_TIMER);
}
@@ -902,7 +898,7 @@
__group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
}
- if (it->expires && (!*expires || it->expires < *expires))
+ if (it->expires && it->expires < *expires)
*expires = it->expires;
}
@@ -915,90 +911,69 @@
struct list_head *firing)
{
struct signal_struct *const sig = tsk->signal;
- u64 utime, ptime, virt_expires, prof_expires;
- u64 sum_sched_runtime, sched_expires;
- struct list_head *timers = sig->cpu_timers;
- struct task_cputime cputime;
+ struct posix_cputimers *pct = &sig->posix_cputimers;
+ u64 samples[CPUCLOCK_MAX];
unsigned long soft;
- if (dl_task(tsk))
- check_dl_overrun(tsk);
-
/*
- * If cputimer is not running, then there are no active
- * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU).
+ * If there are no active process wide timers (POSIX 1.b, itimers,
+ * RLIMIT_CPU) nothing to check. Also skip the process wide timer
+ * processing when there is already another task handling them.
*/
- if (!READ_ONCE(tsk->signal->cputimer.running))
+ if (!READ_ONCE(pct->timers_active) || pct->expiry_active)
return;
- /*
+ /*
* Signify that a thread is checking for process timers.
* Write access to this field is protected by the sighand lock.
*/
- sig->cputimer.checking_timer = true;
+ pct->expiry_active = true;
/*
- * Collect the current process totals.
+ * Collect the current process totals. Group accounting is active
+ * so the sample can be taken directly.
*/
- thread_group_cputimer(tsk, &cputime);
- utime = cputime.utime;
- ptime = utime + cputime.stime;
- sum_sched_runtime = cputime.sum_exec_runtime;
-
- prof_expires = check_timers_list(timers, firing, ptime);
- virt_expires = check_timers_list(++timers, firing, utime);
- sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);
+ proc_sample_cputime_atomic(&sig->cputimer.cputime_atomic, samples);
+ collect_posix_cputimers(pct, samples, firing);
/*
* Check for the special case process timers.
*/
- check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
- SIGPROF);
- check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
- SIGVTALRM);
+ check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF],
+ &pct->bases[CPUCLOCK_PROF].nextevt,
+ samples[CPUCLOCK_PROF], SIGPROF);
+ check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT],
+ &pct->bases[CPUCLOCK_VIRT].nextevt,
+ samples[CPUCLOCK_VIRT], SIGVTALRM);
+
soft = task_rlimit(tsk, RLIMIT_CPU);
if (soft != RLIM_INFINITY) {
- unsigned long psecs = div_u64(ptime, NSEC_PER_SEC);
+ /* RLIMIT_CPU is in seconds. Samples are nanoseconds */
unsigned long hard = task_rlimit_max(tsk, RLIMIT_CPU);
- u64 x;
- if (psecs >= hard) {
- /*
- * At the hard limit, we just die.
- * No need to calculate anything else now.
- */
- if (print_fatal_signals) {
- pr_info("RT Watchdog Timeout (hard): %s[%d]\n",
- tsk->comm, task_pid_nr(tsk));
- }
- __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
+ u64 ptime = samples[CPUCLOCK_PROF];
+ u64 softns = (u64)soft * NSEC_PER_SEC;
+ u64 hardns = (u64)hard * NSEC_PER_SEC;
+
+ /* At the hard limit, send SIGKILL. No further action. */
+ if (hard != RLIM_INFINITY &&
+ check_rlimit(ptime, hardns, SIGKILL, false, true))
return;
+
+ /* At the soft limit, send a SIGXCPU every second */
+ if (check_rlimit(ptime, softns, SIGXCPU, false, false)) {
+ sig->rlim[RLIMIT_CPU].rlim_cur = soft + 1;
+ softns += NSEC_PER_SEC;
}
- if (psecs >= soft) {
- /*
- * At the soft limit, send a SIGXCPU every second.
- */
- if (print_fatal_signals) {
- pr_info("CPU Watchdog Timeout (soft): %s[%d]\n",
- tsk->comm, task_pid_nr(tsk));
- }
- __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
- if (soft < hard) {
- soft++;
- sig->rlim[RLIMIT_CPU].rlim_cur = soft;
- }
- }
- x = soft * NSEC_PER_SEC;
- if (!prof_expires || x < prof_expires)
- prof_expires = x;
+
+ /* Update the expiry cache */
+ if (softns < pct->bases[CPUCLOCK_PROF].nextevt)
+ pct->bases[CPUCLOCK_PROF].nextevt = softns;
}
- sig->cputime_expires.prof_exp = prof_expires;
- sig->cputime_expires.virt_exp = virt_expires;
- sig->cputime_expires.sched_exp = sched_expires;
- if (task_cputime_zero(&sig->cputime_expires))
+ if (expiry_cache_is_inactive(pct))
stop_process_timers(sig);
- sig->cputimer.checking_timer = false;
+ pct->expiry_active = false;
}
/*
@@ -1007,78 +982,60 @@
*/
static void posix_cpu_timer_rearm(struct k_itimer *timer)
{
- struct task_struct *p = timer->it.cpu.task;
+ clockid_t clkid = CPUCLOCK_WHICH(timer->it_clock);
+ struct task_struct *p;
struct sighand_struct *sighand;
unsigned long flags;
u64 now;
- if (WARN_ON_ONCE(!p))
- return;
+ rcu_read_lock();
+ p = cpu_timer_task_rcu(timer);
+ if (!p)
+ goto out;
+
+ /* Protect timer list r/w in arm_timer() */
+ sighand = lock_task_sighand(p, &flags);
+ if (unlikely(sighand == NULL))
+ goto out;
/*
* Fetch the current sample and update the timer's expiry time.
*/
- if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
- cpu_clock_sample(timer->it_clock, p, &now);
- bump_cpu_timer(timer, now);
- if (unlikely(p->exit_state))
- return;
+ if (CPUCLOCK_PERTHREAD(timer->it_clock))
+ now = cpu_clock_sample(clkid, p);
+ else
+ now = cpu_clock_sample_group(clkid, p, true);
- /* Protect timer list r/w in arm_timer() */
- sighand = lock_task_sighand(p, &flags);
- if (!sighand)
- return;
- } else {
- /*
- * Protect arm_timer() and timer sampling in case of call to
- * thread_group_cputime().
- */
- sighand = lock_task_sighand(p, &flags);
- if (unlikely(sighand == NULL)) {
- /*
- * The process has been reaped.
- * We can't even collect a sample any more.
- */
- timer->it.cpu.expires = 0;
- return;
- } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
- /* If the process is dying, no need to rearm */
- goto unlock;
- }
- cpu_timer_sample_group(timer->it_clock, p, &now);
- bump_cpu_timer(timer, now);
- /* Leave the sighand locked for the call below. */
- }
+ bump_cpu_timer(timer, now);
/*
* Now re-arm for the new expiry time.
*/
- arm_timer(timer);
-unlock:
+ arm_timer(timer, p);
unlock_task_sighand(p, &flags);
+out:
+ rcu_read_unlock();
}
/**
- * task_cputime_expired - Compare two task_cputime entities.
+ * task_cputimers_expired - Check whether posix CPU timers are expired
*
- * @sample: The task_cputime structure to be checked for expiration.
- * @expires: Expiration times, against which @sample will be checked.
+ * @samples: Array of current samples for the CPUCLOCK clocks
+ * @pct: Pointer to a posix_cputimers container
*
- * Checks @sample against @expires to see if any field of @sample has expired.
- * Returns true if any field of the former is greater than the corresponding
- * field of the latter if the latter field is set. Otherwise returns false.
+ * Returns true if any member of @samples is greater than the corresponding
+ * member of @pct->bases[CLK].nextevt. False otherwise
*/
-static inline int task_cputime_expired(const struct task_cputime *sample,
- const struct task_cputime *expires)
+static inline bool
+task_cputimers_expired(const u64 *samples, struct posix_cputimers *pct)
{
- if (expires->utime && sample->utime >= expires->utime)
- return 1;
- if (expires->stime && sample->utime + sample->stime >= expires->stime)
- return 1;
- if (expires->sum_exec_runtime != 0 &&
- sample->sum_exec_runtime >= expires->sum_exec_runtime)
- return 1;
- return 0;
+ int i;
+
+ for (i = 0; i < CPUCLOCK_MAX; i++) {
+ if (samples[i] >= pct->bases[i].nextevt)
+ return true;
+ }
+ return false;
}
/**
@@ -1091,83 +1048,279 @@
* timers and compare them with the corresponding expiration times. Return
* true if a timer has expired, else return false.
*/
-static inline int fastpath_timer_check(struct task_struct *tsk)
+static inline bool fastpath_timer_check(struct task_struct *tsk)
{
+ struct posix_cputimers *pct = &tsk->posix_cputimers;
struct signal_struct *sig;
- if (!task_cputime_zero(&tsk->cputime_expires)) {
- struct task_cputime task_sample;
+ if (!expiry_cache_is_inactive(pct)) {
+ u64 samples[CPUCLOCK_MAX];
- task_cputime(tsk, &task_sample.utime, &task_sample.stime);
- task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
- if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
- return 1;
+ task_sample_cputime(tsk, samples);
+ if (task_cputimers_expired(samples, pct))
+ return true;
}
sig = tsk->signal;
+ pct = &sig->posix_cputimers;
/*
- * Check if thread group timers expired when the cputimer is
- * running and no other thread in the group is already checking
- * for thread group cputimers. These fields are read without the
- * sighand lock. However, this is fine because this is meant to
- * be a fastpath heuristic to determine whether we should try to
- * acquire the sighand lock to check/handle timers.
+ * Check if thread group timers expired when timers are active and
+ * no other thread in the group is already handling expiry for
+ * thread group cputimers. These fields are read without the
+ * sighand lock. However, this is fine because this is meant to be
+ * a fastpath heuristic to determine whether we should try to
+ * acquire the sighand lock to handle timer expiry.
*
- * In the worst case scenario, if 'running' or 'checking_timer' gets
- * set but the current thread doesn't see the change yet, we'll wait
- * until the next thread in the group gets a scheduler interrupt to
- * handle the timer. This isn't an issue in practice because these
- * types of delays with signals actually getting sent are expected.
+ * In the worst case scenario, if concurrently timers_active is set
+ * or expiry_active is cleared, but the current thread doesn't see
+ * the change yet, the timer checks are delayed until the next
+ * thread in the group gets a scheduler interrupt to handle the
+ * timer. This isn't an issue in practice because these types of
+ * delays with signals actually getting sent are expected.
*/
- if (READ_ONCE(sig->cputimer.running) &&
- !READ_ONCE(sig->cputimer.checking_timer)) {
- struct task_cputime group_sample;
+ if (READ_ONCE(pct->timers_active) && !READ_ONCE(pct->expiry_active)) {
+ u64 samples[CPUCLOCK_MAX];
- sample_cputime_atomic(&group_sample, &sig->cputimer.cputime_atomic);
+ proc_sample_cputime_atomic(&sig->cputimer.cputime_atomic,
+ samples);
- if (task_cputime_expired(&group_sample, &sig->cputime_expires))
- return 1;
+ if (task_cputimers_expired(samples, pct))
+ return true;
}
if (dl_task(tsk) && tsk->dl.dl_overrun)
- return 1;
+ return true;
- return 0;
+ return false;
+}
+
+static void handle_posix_cpu_timers(struct task_struct *tsk);
+
+#ifdef CONFIG_POSIX_CPU_TIMERS_TASK_WORK
+static void posix_cpu_timers_work(struct callback_head *work)
+{
+ struct posix_cputimers_work *cw = container_of(work, typeof(*cw), work);
+
+ mutex_lock(&cw->mutex);
+ handle_posix_cpu_timers(current);
+ mutex_unlock(&cw->mutex);
}
/*
- * This is called from the timer interrupt handler. The irq handler has
- * already updated our counts. We need to check if any timers fire now.
- * Interrupts are disabled.
+ * Invoked from the posix-timer core when a cancel operation failed because
+ * the timer is marked firing. The caller holds rcu_read_lock(), which
+ * protects the timer and the task which is expiring it from being freed.
*/
-void run_posix_cpu_timers(struct task_struct *tsk)
+static void posix_cpu_timer_wait_running(struct k_itimer *timr)
{
- LIST_HEAD(firing);
- struct k_itimer *timer, *next;
- unsigned long flags;
+ struct task_struct *tsk = rcu_dereference(timr->it.cpu.handling);
- lockdep_assert_irqs_disabled();
+ /* Has the handling task completed expiry already? */
+ if (!tsk)
+ return;
+
+ /* Ensure that the task cannot go away */
+ get_task_struct(tsk);
+ /* Now drop the RCU protection so the mutex can be locked */
+ rcu_read_unlock();
+ /* Wait on the expiry mutex */
+ mutex_lock(&tsk->posix_cputimers_work.mutex);
+ /* Release it immediately again. */
+ mutex_unlock(&tsk->posix_cputimers_work.mutex);
+ /* Drop the task reference. */
+ put_task_struct(tsk);
+ /* Relock RCU so the callsite is balanced */
+ rcu_read_lock();
+}
+
+static void posix_cpu_timer_wait_running_nsleep(struct k_itimer *timr)
+{
+ /* Ensure that timr->it.cpu.handling task cannot go away */
+ rcu_read_lock();
+ spin_unlock_irq(&timr->it_lock);
+ posix_cpu_timer_wait_running(timr);
+ rcu_read_unlock();
+ /* @timr is on stack and is valid */
+ spin_lock_irq(&timr->it_lock);
+}
+
+/*
+ * Clear existing posix CPU timers task work.
+ */
+void clear_posix_cputimers_work(struct task_struct *p)
+{
+ /*
+ * A copied work entry from the old task is not meaningful, clear it.
+ * N.B. init_task_work will not do this.
+ */
+ memset(&p->posix_cputimers_work.work, 0,
+ sizeof(p->posix_cputimers_work.work));
+ init_task_work(&p->posix_cputimers_work.work,
+ posix_cpu_timers_work);
+ mutex_init(&p->posix_cputimers_work.mutex);
+ p->posix_cputimers_work.scheduled = false;
+}
+
+/*
+ * Initialize posix CPU timers task work in init task. Out of line to
+ * keep the callback static and to avoid header recursion hell.
+ */
+void __init posix_cputimers_init_work(void)
+{
+ clear_posix_cputimers_work(current);
+}
+
+/*
+ * Note: All operations on tsk->posix_cputimer_work.scheduled happen either
+ * in hard interrupt context or in task context with interrupts
+ * disabled. Aside of that the writer/reader interaction is always in the
+ * context of the current task, which means they are strict per CPU.
+ */
+static inline bool posix_cpu_timers_work_scheduled(struct task_struct *tsk)
+{
+ return tsk->posix_cputimers_work.scheduled;
+}
+
+static inline void __run_posix_cpu_timers(struct task_struct *tsk)
+{
+ if (WARN_ON_ONCE(tsk->posix_cputimers_work.scheduled))
+ return;
+
+ /* Schedule task work to actually expire the timers */
+ tsk->posix_cputimers_work.scheduled = true;
+ task_work_add(tsk, &tsk->posix_cputimers_work.work, TWA_RESUME);
+}
+
+static inline bool posix_cpu_timers_enable_work(struct task_struct *tsk,
+ unsigned long start)
+{
+ bool ret = true;
/*
- * The fast path checks that there are no expired thread or thread
- * group timers. If that's so, just return.
+ * On !RT kernels interrupts are disabled while collecting expired
+ * timers, so no tick can happen and the fast path check can be
+ * reenabled without further checks.
*/
- if (!fastpath_timer_check(tsk))
- return;
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
+ tsk->posix_cputimers_work.scheduled = false;
+ return true;
+ }
+
+ /*
+ * On RT enabled kernels ticks can happen while the expired timers
+ * are collected under sighand lock. But any tick which observes
+ * the CPUTIMERS_WORK_SCHEDULED bit set, does not run the fastpath
+ * checks. So reenabling the tick work has do be done carefully:
+ *
+ * Disable interrupts and run the fast path check if jiffies have
+ * advanced since the collecting of expired timers started. If
+ * jiffies have not advanced or the fast path check did not find
+ * newly expired timers, reenable the fast path check in the timer
+ * interrupt. If there are newly expired timers, return false and
+ * let the collection loop repeat.
+ */
+ local_irq_disable();
+ if (start != jiffies && fastpath_timer_check(tsk))
+ ret = false;
+ else
+ tsk->posix_cputimers_work.scheduled = false;
+ local_irq_enable();
+
+ return ret;
+}
+#else /* CONFIG_POSIX_CPU_TIMERS_TASK_WORK */
+static inline void __run_posix_cpu_timers(struct task_struct *tsk)
+{
+ lockdep_posixtimer_enter();
+ handle_posix_cpu_timers(tsk);
+ lockdep_posixtimer_exit();
+}
+
+static void posix_cpu_timer_wait_running(struct k_itimer *timr)
+{
+ cpu_relax();
+}
+
+static void posix_cpu_timer_wait_running_nsleep(struct k_itimer *timr)
+{
+ spin_unlock_irq(&timr->it_lock);
+ cpu_relax();
+ spin_lock_irq(&timr->it_lock);
+}
+
+static inline bool posix_cpu_timers_work_scheduled(struct task_struct *tsk)
+{
+ return false;
+}
+
+static inline bool posix_cpu_timers_enable_work(struct task_struct *tsk,
+ unsigned long start)
+{
+ return true;
+}
+#endif /* CONFIG_POSIX_CPU_TIMERS_TASK_WORK */
+
+static void handle_posix_cpu_timers(struct task_struct *tsk)
+{
+ struct k_itimer *timer, *next;
+ unsigned long flags, start;
+ LIST_HEAD(firing);
if (!lock_task_sighand(tsk, &flags))
return;
- /*
- * Here we take off tsk->signal->cpu_timers[N] and
- * tsk->cpu_timers[N] all the timers that are firing, and
- * put them on the firing list.
- */
- check_thread_timers(tsk, &firing);
- check_process_timers(tsk, &firing);
+ do {
+ /*
+ * On RT locking sighand lock does not disable interrupts,
+ * so this needs to be careful vs. ticks. Store the current
+ * jiffies value.
+ */
+ start = READ_ONCE(jiffies);
+ barrier();
+
+ /*
+ * Here we take off tsk->signal->cpu_timers[N] and
+ * tsk->cpu_timers[N] all the timers that are firing, and
+ * put them on the firing list.
+ */
+ check_thread_timers(tsk, &firing);
+
+ check_process_timers(tsk, &firing);
+
+ /*
+ * The above timer checks have updated the exipry cache and
+ * because nothing can have queued or modified timers after
+ * sighand lock was taken above it is guaranteed to be
+ * consistent. So the next timer interrupt fastpath check
+ * will find valid data.
+ *
+ * If timer expiry runs in the timer interrupt context then
+ * the loop is not relevant as timers will be directly
+ * expired in interrupt context. The stub function below
+ * returns always true which allows the compiler to
+ * optimize the loop out.
+ *
+ * If timer expiry is deferred to task work context then
+ * the following rules apply:
+ *
+ * - On !RT kernels no tick can have happened on this CPU
+ * after sighand lock was acquired because interrupts are
+ * disabled. So reenabling task work before dropping
+ * sighand lock and reenabling interrupts is race free.
+ *
+ * - On RT kernels ticks might have happened but the tick
+ * work ignored posix CPU timer handling because the
+ * CPUTIMERS_WORK_SCHEDULED bit is set. Reenabling work
+ * must be done very carefully including a check whether
+ * ticks have happened since the start of the timer
+ * expiry checks. posix_cpu_timers_enable_work() takes
+ * care of that and eventually lets the expiry checks
+ * run again.
+ */
+ } while (!posix_cpu_timers_enable_work(tsk, start));
/*
- * We must release these locks before taking any timer's lock.
+ * We must release sighand lock before taking any timer's lock.
* There is a potential race with timer deletion here, as the
* siglock now protects our private firing list. We have set
* the firing flag in each timer, so that a deletion attempt
@@ -1182,11 +1335,18 @@
* each timer's lock before clearing its firing flag, so no
* timer call will interfere.
*/
- list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
+ list_for_each_entry_safe(timer, next, &firing, it.cpu.elist) {
int cpu_firing;
+ /*
+ * spin_lock() is sufficient here even independent of the
+ * expiry context. If expiry happens in hard interrupt
+ * context it's obvious. For task work context it's safe
+ * because all other operations on timer::it_lock happen in
+ * task context (syscall or exit).
+ */
spin_lock(&timer->it_lock);
- list_del_init(&timer->it.cpu.entry);
+ list_del_init(&timer->it.cpu.elist);
cpu_firing = timer->it.cpu.firing;
timer->it.cpu.firing = 0;
/*
@@ -1196,26 +1356,56 @@
*/
if (likely(cpu_firing >= 0))
cpu_timer_fire(timer);
+ /* See posix_cpu_timer_wait_running() */
+ rcu_assign_pointer(timer->it.cpu.handling, NULL);
spin_unlock(&timer->it_lock);
}
+}
+
+/*
+ * This is called from the timer interrupt handler. The irq handler has
+ * already updated our counts. We need to check if any timers fire now.
+ * Interrupts are disabled.
+ */
+void run_posix_cpu_timers(void)
+{
+ struct task_struct *tsk = current;
+
+ lockdep_assert_irqs_disabled();
+
+ /*
+ * If the actual expiry is deferred to task work context and the
+ * work is already scheduled there is no point to do anything here.
+ */
+ if (posix_cpu_timers_work_scheduled(tsk))
+ return;
+
+ /*
+ * The fast path checks that there are no expired thread or thread
+ * group timers. If that's so, just return.
+ */
+ if (!fastpath_timer_check(tsk))
+ return;
+
+ __run_posix_cpu_timers(tsk);
}
/*
* Set one of the process-wide special case CPU timers or RLIMIT_CPU.
* The tsk->sighand->siglock must be held by the caller.
*/
-void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
+void set_process_cpu_timer(struct task_struct *tsk, unsigned int clkid,
u64 *newval, u64 *oldval)
{
- u64 now;
- int ret;
+ u64 now, *nextevt;
- if (WARN_ON_ONCE(clock_idx >= CPUCLOCK_SCHED))
+ if (WARN_ON_ONCE(clkid >= CPUCLOCK_SCHED))
return;
- ret = cpu_timer_sample_group(clock_idx, tsk, &now);
+ nextevt = &tsk->signal->posix_cputimers.bases[clkid].nextevt;
+ now = cpu_clock_sample_group(clkid, tsk, true);
- if (oldval && ret != -EINVAL) {
+ if (oldval) {
/*
* We are setting itimer. The *oldval is absolute and we update
* it to be relative, *newval argument is relative and we update
@@ -1236,19 +1426,11 @@
}
/*
- * Update expiration cache if we are the earliest timer, or eventually
- * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
+ * Update expiration cache if this is the earliest timer. CPUCLOCK_PROF
+ * expiry cache is also used by RLIMIT_CPU!.
*/
- switch (clock_idx) {
- case CPUCLOCK_PROF:
- if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
- tsk->signal->cputime_expires.prof_exp = *newval;
- break;
- case CPUCLOCK_VIRT:
- if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
- tsk->signal->cputime_expires.virt_exp = *newval;
- break;
- }
+ if (*newval < *nextevt)
+ *nextevt = *newval;
tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER);
}
@@ -1270,6 +1452,7 @@
timer.it_overrun = -1;
error = posix_cpu_timer_create(&timer);
timer.it_process = current;
+
if (!error) {
static struct itimerspec64 zero_it;
struct restart_block *restart;
@@ -1285,7 +1468,7 @@
}
while (!signal_pending(current)) {
- if (timer.it.cpu.expires == 0) {
+ if (!cpu_timer_getexpires(&timer.it.cpu)) {
/*
* Our timer fired and was reset, below
* deletion can not fail.
@@ -1307,26 +1490,19 @@
/*
* We were interrupted by a signal.
*/
- expires = timer.it.cpu.expires;
+ expires = cpu_timer_getexpires(&timer.it.cpu);
error = posix_cpu_timer_set(&timer, 0, &zero_it, &it);
if (!error) {
- /*
- * Timer is now unarmed, deletion can not fail.
- */
+ /* Timer is now unarmed, deletion can not fail. */
posix_cpu_timer_del(&timer);
+ } else {
+ while (error == TIMER_RETRY) {
+ posix_cpu_timer_wait_running_nsleep(&timer);
+ error = posix_cpu_timer_del(&timer);
+ }
}
- spin_unlock_irq(&timer.it_lock);
- while (error == TIMER_RETRY) {
- /*
- * We need to handle case when timer was or is in the
- * middle of firing. In other cases we already freed
- * resources.
- */
- spin_lock_irq(&timer.it_lock);
- error = posix_cpu_timer_del(&timer);
- spin_unlock_irq(&timer.it_lock);
- }
+ spin_unlock_irq(&timer.it_lock);
if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) {
/*
@@ -1427,26 +1603,27 @@
}
const struct k_clock clock_posix_cpu = {
- .clock_getres = posix_cpu_clock_getres,
- .clock_set = posix_cpu_clock_set,
- .clock_get = posix_cpu_clock_get,
- .timer_create = posix_cpu_timer_create,
- .nsleep = posix_cpu_nsleep,
- .timer_set = posix_cpu_timer_set,
- .timer_del = posix_cpu_timer_del,
- .timer_get = posix_cpu_timer_get,
- .timer_rearm = posix_cpu_timer_rearm,
+ .clock_getres = posix_cpu_clock_getres,
+ .clock_set = posix_cpu_clock_set,
+ .clock_get_timespec = posix_cpu_clock_get,
+ .timer_create = posix_cpu_timer_create,
+ .nsleep = posix_cpu_nsleep,
+ .timer_set = posix_cpu_timer_set,
+ .timer_del = posix_cpu_timer_del,
+ .timer_get = posix_cpu_timer_get,
+ .timer_rearm = posix_cpu_timer_rearm,
+ .timer_wait_running = posix_cpu_timer_wait_running,
};
const struct k_clock clock_process = {
- .clock_getres = process_cpu_clock_getres,
- .clock_get = process_cpu_clock_get,
- .timer_create = process_cpu_timer_create,
- .nsleep = process_cpu_nsleep,
+ .clock_getres = process_cpu_clock_getres,
+ .clock_get_timespec = process_cpu_clock_get,
+ .timer_create = process_cpu_timer_create,
+ .nsleep = process_cpu_nsleep,
};
const struct k_clock clock_thread = {
- .clock_getres = thread_cpu_clock_getres,
- .clock_get = thread_cpu_clock_get,
- .timer_create = thread_cpu_timer_create,
+ .clock_getres = thread_cpu_clock_getres,
+ .clock_get_timespec = thread_cpu_clock_get,
+ .timer_create = thread_cpu_timer_create,
};
--
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