add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/hv/hv_snapshot.c
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@@ -1,20 +1,9 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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 /*
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  * An implementation of host initiated guest snapshot.
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  *
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- *
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  * Copyright (C) 2013, Microsoft, Inc.
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  * Author : K. Y. Srinivasan <kys@microsoft.com>
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- *
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- * This program is free software; you can redistribute it and/or modify it
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- * under the terms of the GNU General Public License version 2 as published
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- * by the Free Software Foundation.
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- *
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- * This program is distributed in the hope that it will be useful, but
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- * WITHOUT ANY WARRANTY; without even the implied warranty of
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- * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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- * NON INFRINGEMENT.  See the GNU General Public License for more
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- * details.
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- *
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  */
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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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9
 
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@@ -23,6 +12,7 @@
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 #include <linux/connector.h>
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 #include <linux/workqueue.h>
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 #include <linux/hyperv.h>
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+#include <asm/hyperv-tlfs.h>
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 #include "hyperv_vmbus.h"
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 #include "hv_utils_transport.h"
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@@ -90,7 +80,7 @@
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 {
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 	/* Transaction is finished, reset the state here to avoid races. */
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 	vss_transaction.state = HVUTIL_READY;
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-	hv_vss_onchannelcallback(channel);
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+	tasklet_schedule(&((struct vmbus_channel *)channel)->callback_event);
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 }
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 /*
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@@ -308,7 +298,7 @@
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 	if (vss_transaction.state > HVUTIL_READY)
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 		return;
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-	vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
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+	vmbus_recvpacket(channel, recv_buffer, HV_HYP_PAGE_SIZE * 2, &recvlen,
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 			 &requestid);
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 	if (recvlen > 0) {
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@@ -389,10 +379,61 @@
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 	return 0;
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 }
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+static void hv_vss_cancel_work(void)
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+{
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+	cancel_delayed_work_sync(&vss_timeout_work);
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+	cancel_work_sync(&vss_handle_request_work);
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+}
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+
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+int hv_vss_pre_suspend(void)
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+{
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+	struct vmbus_channel *channel = vss_transaction.recv_channel;
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+	struct hv_vss_msg *vss_msg;
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+
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+	/*
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+	 * Fake a THAW message for the user space daemon in case the daemon
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+	 * has frozen the file systems. It doesn't matter if there is already
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+	 * a message pending to be delivered to the user space since we force
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+	 * vss_transaction.state to be HVUTIL_READY, so the user space daemon's
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+	 * write() will fail with EINVAL (see vss_on_msg()), and the daemon
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+	 * will reset the device by closing and re-opening it.
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+	 */
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+	vss_msg = kzalloc(sizeof(*vss_msg), GFP_KERNEL);
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+	if (!vss_msg)
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+		return -ENOMEM;
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+
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+	tasklet_disable(&channel->callback_event);
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+
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+	vss_msg->vss_hdr.operation = VSS_OP_THAW;
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+
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+	/* Cancel any possible pending work. */
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+	hv_vss_cancel_work();
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+
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+	/* We don't care about the return value. */
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+	hvutil_transport_send(hvt, vss_msg, sizeof(*vss_msg), NULL);
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+
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+	kfree(vss_msg);
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+
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+	vss_transaction.state = HVUTIL_READY;
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+
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+	/* tasklet_enable() will be called in hv_vss_pre_resume(). */
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+	return 0;
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+}
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+
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+int hv_vss_pre_resume(void)
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+{
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+	struct vmbus_channel *channel = vss_transaction.recv_channel;
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+
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+	tasklet_enable(&channel->callback_event);
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+
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+	return 0;
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+}
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+
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 void hv_vss_deinit(void)
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 {
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 	vss_transaction.state = HVUTIL_DEVICE_DYING;
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-	cancel_delayed_work_sync(&vss_timeout_work);
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-	cancel_work_sync(&vss_handle_request_work);
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+
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+	hv_vss_cancel_work();
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+
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 	hvutil_transport_destroy(hvt);
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 }