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>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index 5f21ab2..0854770 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -22,6 +22,7 @@
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/freezer.h>
+#include <scsi/scsi_scan.h>
#include <asm/suspend.h>
#include "power.h"
@@ -645,6 +646,13 @@
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
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 6c85359..ed97375 100644
--- a/kernel/power/user.c
+++ b/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 @@
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 @@
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);