From 093a6c67005148ae32a5c9e4553491b9f5c2457b Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 10 May 2024 07:40:51 +0000
Subject: [PATCH] disable kernel build waring

---
 kernel/include/linux/preempt.h |  190 +++++++++--------------------------------------
 1 files changed, 38 insertions(+), 152 deletions(-)

diff --git a/kernel/include/linux/preempt.h b/kernel/include/linux/preempt.h
index 7b5b2ed..7d9c1c0 100644
--- a/kernel/include/linux/preempt.h
+++ b/kernel/include/linux/preempt.h
@@ -77,37 +77,31 @@
 /* preempt_count() and related functions, depends on PREEMPT_NEED_RESCHED */
 #include <asm/preempt.h>
 
-#define nmi_count()	(preempt_count() & NMI_MASK)
 #define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
-#ifdef CONFIG_PREEMPT_RT
-# define softirq_count()	(current->softirq_disable_cnt & SOFTIRQ_MASK)
-#else
-# define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
-#endif
-#define irq_count()	(nmi_count() | hardirq_count() | softirq_count())
+#define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
+#define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
+				 | NMI_MASK))
 
 /*
- * Macros to retrieve the current execution context:
+ * Are we doing bottom half or hardware interrupt processing?
  *
- * in_nmi()		- We're in NMI context
- * in_hardirq()		- We're in hard IRQ context
- * in_serving_softirq()	- We're in softirq context
- * in_task()		- We're in task context
- */
-#define in_nmi()		(nmi_count())
-#define in_hardirq()		(hardirq_count())
-#define in_serving_softirq()	(softirq_count() & SOFTIRQ_OFFSET)
-#define in_task()		(!(in_nmi() | in_hardirq() | in_serving_softirq()))
-
-/*
- * The following macros are deprecated and should not be used in new code:
- * in_irq()       - Obsolete version of in_hardirq()
+ * in_irq()       - We're in (hard) IRQ context
  * in_softirq()   - We have BH disabled, or are processing softirqs
  * in_interrupt() - We're in NMI,IRQ,SoftIRQ context or have BH disabled
+ * in_serving_softirq() - We're in softirq context
+ * in_nmi()       - We're in NMI context
+ * in_task()	  - We're in task context
+ *
+ * Note: due to the BH disabled confusion: in_softirq(),in_interrupt() really
+ *       should not be used in new code.
  */
 #define in_irq()		(hardirq_count())
 #define in_softirq()		(softirq_count())
 #define in_interrupt()		(irq_count())
+#define in_serving_softirq()	(softirq_count() & SOFTIRQ_OFFSET)
+#define in_nmi()		(preempt_count() & NMI_MASK)
+#define in_task()		(!(preempt_count() & \
+				   (NMI_MASK | HARDIRQ_MASK | SOFTIRQ_OFFSET)))
 
 /*
  * The preempt_count offset after preempt_disable();
@@ -121,11 +115,7 @@
 /*
  * The preempt_count offset after spin_lock()
  */
-#if !defined(CONFIG_PREEMPT_RT)
 #define PREEMPT_LOCK_OFFSET	PREEMPT_DISABLE_OFFSET
-#else
-#define PREEMPT_LOCK_OFFSET	0
-#endif
 
 /*
  * The preempt_count offset needed for things like:
@@ -174,31 +164,11 @@
 #define preempt_count_inc() preempt_count_add(1)
 #define preempt_count_dec() preempt_count_sub(1)
 
-#ifdef CONFIG_PREEMPT_LAZY
-#define add_preempt_lazy_count(val)	do { preempt_lazy_count() += (val); } while (0)
-#define sub_preempt_lazy_count(val)	do { preempt_lazy_count() -= (val); } while (0)
-#define inc_preempt_lazy_count()	add_preempt_lazy_count(1)
-#define dec_preempt_lazy_count()	sub_preempt_lazy_count(1)
-#define preempt_lazy_count()		(current_thread_info()->preempt_lazy_count)
-#else
-#define add_preempt_lazy_count(val)	do { } while (0)
-#define sub_preempt_lazy_count(val)	do { } while (0)
-#define inc_preempt_lazy_count()	do { } while (0)
-#define dec_preempt_lazy_count()	do { } while (0)
-#define preempt_lazy_count()		(0)
-#endif
-
 #ifdef CONFIG_PREEMPT_COUNT
 
 #define preempt_disable() \
 do { \
 	preempt_count_inc(); \
-	barrier(); \
-} while (0)
-
-#define preempt_lazy_disable() \
-do { \
-	inc_preempt_lazy_count(); \
 	barrier(); \
 } while (0)
 
@@ -208,13 +178,7 @@
 	preempt_count_dec(); \
 } while (0)
 
-#ifndef CONFIG_PREEMPT_RT
-# define preempt_enable_no_resched() sched_preempt_enable_no_resched()
-# define preempt_check_resched_rt() barrier();
-#else
-# define preempt_enable_no_resched() preempt_enable()
-# define preempt_check_resched_rt() preempt_check_resched()
-#endif
+#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
 
 #define preemptible()	(preempt_count() == 0 && !irqs_disabled())
 
@@ -239,29 +203,11 @@
 		__preempt_schedule(); \
 } while (0)
 
-/*
- * open code preempt_check_resched() because it is not exported to modules and
- * used by local_unlock() or bpf_enable_instrumentation().
- */
-#define preempt_lazy_enable() \
-do { \
-	dec_preempt_lazy_count(); \
-	barrier(); \
-	if (should_resched(0)) \
-		__preempt_schedule(); \
-} while (0)
-
 #else /* !CONFIG_PREEMPTION */
 #define preempt_enable() \
 do { \
 	barrier(); \
 	preempt_count_dec(); \
-} while (0)
-
-#define preempt_lazy_enable() \
-do { \
-	dec_preempt_lazy_count(); \
-	barrier(); \
 } while (0)
 
 #define preempt_enable_notrace() \
@@ -302,11 +248,7 @@
 #define preempt_disable_notrace()		barrier()
 #define preempt_enable_no_resched_notrace()	barrier()
 #define preempt_enable_notrace()		barrier()
-#define preempt_check_resched_rt()		barrier()
 #define preemptible()				0
-
-#define preempt_lazy_disable()			barrier()
-#define preempt_lazy_enable()			barrier()
 
 #endif /* CONFIG_PREEMPT_COUNT */
 
@@ -326,21 +268,9 @@
 } while (0)
 #define preempt_fold_need_resched() \
 do { \
-	if (tif_need_resched_now()) \
+	if (tif_need_resched()) \
 		set_preempt_need_resched(); \
 } while (0)
-
-#ifdef CONFIG_PREEMPT_RT
-# define preempt_disable_rt()		preempt_disable()
-# define preempt_enable_rt()		preempt_enable()
-# define preempt_disable_nort()		barrier()
-# define preempt_enable_nort()		barrier()
-#else
-# define preempt_disable_rt()		barrier()
-# define preempt_enable_rt()		barrier()
-# define preempt_disable_nort()		preempt_disable()
-# define preempt_enable_nort()		preempt_enable()
-#endif
 
 #ifdef CONFIG_PREEMPT_NOTIFIERS
 
@@ -392,78 +322,34 @@
 
 #endif
 
-#ifdef CONFIG_SMP
-
-/*
- * Migrate-Disable and why it is undesired.
+/**
+ * migrate_disable - Prevent migration of the current task
  *
- * When a preempted task becomes elegible to run under the ideal model (IOW it
- * becomes one of the M highest priority tasks), it might still have to wait
- * for the preemptee's migrate_disable() section to complete. Thereby suffering
- * a reduction in bandwidth in the exact duration of the migrate_disable()
- * section.
+ * Maps to preempt_disable() which also disables preemption. Use
+ * migrate_disable() to annotate that the intent is to prevent migration,
+ * but not necessarily preemption.
  *
- * Per this argument, the change from preempt_disable() to migrate_disable()
- * gets us:
- *
- * - a higher priority tasks gains reduced wake-up latency; with preempt_disable()
- *   it would have had to wait for the lower priority task.
- *
- * - a lower priority tasks; which under preempt_disable() could've instantly
- *   migrated away when another CPU becomes available, is now constrained
- *   by the ability to push the higher priority task away, which might itself be
- *   in a migrate_disable() section, reducing it's available bandwidth.
- *
- * IOW it trades latency / moves the interference term, but it stays in the
- * system, and as long as it remains unbounded, the system is not fully
- * deterministic.
- *
- *
- * The reason we have it anyway.
- *
- * PREEMPT_RT breaks a number of assumptions traditionally held. By forcing a
- * number of primitives into becoming preemptible, they would also allow
- * migration. This turns out to break a bunch of per-cpu usage. To this end,
- * all these primitives employ migirate_disable() to restore this implicit
- * assumption.
- *
- * This is a 'temporary' work-around at best. The correct solution is getting
- * rid of the above assumptions and reworking the code to employ explicit
- * per-cpu locking or short preempt-disable regions.
- *
- * The end goal must be to get rid of migrate_disable(), alternatively we need
- * a schedulability theory that does not depend on abritrary migration.
- *
- *
- * Notes on the implementation.
- *
- * The implementation is particularly tricky since existing code patterns
- * dictate neither migrate_disable() nor migrate_enable() is allowed to block.
- * This means that it cannot use cpus_read_lock() to serialize against hotplug,
- * nor can it easily migrate itself into a pending affinity mask change on
- * migrate_enable().
- *
- *
- * Note: even non-work-conserving schedulers like semi-partitioned depends on
- *       migration, so migrate_disable() is not only a problem for
- *       work-conserving schedulers.
- *
+ * Can be invoked nested like preempt_disable() and needs the corresponding
+ * number of migrate_enable() invocations.
  */
-extern void migrate_disable(void);
-extern void migrate_enable(void);
-
-#else
-
-static inline void migrate_disable(void)
+static __always_inline void migrate_disable(void)
 {
-	preempt_lazy_disable();
+	preempt_disable();
 }
 
-static inline void migrate_enable(void)
+/**
+ * migrate_enable - Allow migration of the current task
+ *
+ * Counterpart to migrate_disable().
+ *
+ * As migrate_disable() can be invoked nested, only the outermost invocation
+ * reenables migration.
+ *
+ * Currently mapped to preempt_enable().
+ */
+static __always_inline void migrate_enable(void)
 {
-	preempt_lazy_enable();
+	preempt_enable();
 }
-
-#endif /* CONFIG_SMP */
 
 #endif /* __LINUX_PREEMPT_H */

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