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From: Rafael J. Wysocki <rjw@suse.com>
Organization: SUSE
To: Arjan van de Ven <arjan@linux.intel.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>
OK, updated patch follows, with a changelog.
I've added this check to user.c too, because that code can be called
independently of the one in disk.c . Also, if resume is user space-driven,
it's a good idea to wait for all of the device probes to complete before
continuing.
Thanks,
Rafael
---
From: Rafael J. Wysocki <rjw@sisk.pl>
Subject: PM/Hibernate: Wait for SCSI devices scan to complete during resume
There is a race between resume from hibernation and the asynchronous
scanning of SCSI devices and to prevent it from happening we need to
call scsi_complete_async_scans() during resume from hibernation.
In addition, if the resume from hibernation is userland-driven, it's
better to wait for all device probes in the kernel to complete before
attempting to open the resume device.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/scsi/scsi_priv.h | 3 ---
drivers/scsi/scsi_wait_scan.c | 2 +-
include/scsi/scsi_scan.h | 11 +++++++++++
kernel/power/disk.c | 8 ++++++++
kernel/power/user.c | 9 +++++++++
5 files changed, 29 insertions(+), 4 deletions(-)
Index: linux-2.6/include/scsi/scsi_scan.h
===================================================================
--- /dev/null
+++ linux-2.6/include/scsi/scsi_scan.h
@@ -0,0 +1,11 @@
+#ifndef _SCSI_SCSI_SCAN_H
+#define _SCSI_SCSI_SCAN_H
+
+#ifdef CONFIG_SCSI
+/* drivers/scsi/scsi_scan.c */
+extern int scsi_complete_async_scans(void);
+#else
+static inline int scsi_complete_async_scans(void) { return 0; }
+#endif
+
+#endif /* _SCSI_SCSI_SCAN_H */
Index: linux-2.6/drivers/scsi/scsi_priv.h
===================================================================
--- linux-2.6.orig/drivers/scsi/scsi_priv.h
+++ linux-2.6/drivers/scsi/scsi_priv.h
@@ -38,9 +38,6 @@ static inline void scsi_log_completion(s
{ };
#endif
-/* scsi_scan.c */
-int scsi_complete_async_scans(void);
-
/* scsi_devinfo.c */
extern int scsi_get_device_flags(struct scsi_device *sdev,
const unsigned char *vendor,
Index: linux-2.6/drivers/scsi/scsi_wait_scan.c
===================================================================
--- linux-2.6.orig/drivers/scsi/scsi_wait_scan.c
+++ linux-2.6/drivers/scsi/scsi_wait_scan.c
@@ -11,7 +11,7 @@
*/
#include <linux/module.h>
-#include "scsi_priv.h"
+#include <scsi/scsi_scan.h>
static int __init wait_scan_init(void)
{
Index: linux-2.6/kernel/power/disk.c
===================================================================
--- linux-2.6.orig/kernel/power/disk.c
+++ linux-2.6/kernel/power/disk.c
@@ -22,5 +22,6 @@
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/freezer.h>
+#include <scsi/scsi_scan.h>
#include "power.h"
@@ -645,6 +646,13 @@ static int software_resume(void)
return 0;
/*
+ * We can't depend on SCSI devices being available after loading one of
+ * their modules if scsi_complete_async_scans() is not called and the
+ * resume device usually is a SCSI one.
+ */
+ scsi_complete_async_scans();
+
+ /*
* name_to_dev_t() below takes a sysfs buffer mutex when sysfs
* is configured into the kernel. Since the regular hibernate
* trigger path is via sysfs which takes a buffer mutex before
Index: linux-2.6/kernel/power/user.c
===================================================================
--- linux-2.6.orig/kernel/power/user.c
+++ linux-2.6/kernel/power/user.c
@@ -24,6 +24,7 @@
#include <linux/cpu.h>
#include <linux/freezer.h>
#include <linux/smp_lock.h>
+#include <scsi/scsi_scan.h>
#include <asm/uaccess.h>
@@ -92,6 +93,7 @@ static int snapshot_open(struct inode *i
filp->private_data = data;
memset(&data->handle, 0, sizeof(struct snapshot_handle));
if ((filp->f_flags & O_ACCMODE) == O_RDONLY) {
+ /* Hibernating. The image device should be accessible. */
data->swap = swsusp_resume_device ?
swap_type_of(swsusp_resume_device, 0, NULL) : -1;
data->mode = O_RDONLY;
@@ -99,6 +101,13 @@ static int snapshot_open(struct inode *i
if (error)
pm_notifier_call_chain(PM_POST_HIBERNATION);
} else {
+ /*
+ * Resuming. We may need to wait for the image device to
+ * appear.
+ */
+ wait_for_device_probe();
+ scsi_complete_async_scans();
+
data->swap = -1;
data->mode = O_WRONLY;
error = pm_notifier_call_chain(PM_RESTORE_PREPARE);
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