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Make wait_for_device_probe() also do scsi_complete_async_scans()

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Commit a7a20d1039 ("sd: limit the scope of the async probe domain")
make the SCSI device probing run device discovery in it's own async
domain.

However, as a result, the partition detection was no longer synchronized
by async_synchronize_full() (which, despite the name, only synchronizes
the global async space, not all of them).  Which in turn meant that
"wait_for_device_probe()" would not wait for the SCSI partitions to be
parsed.

And "wait_for_device_probe()" was what the boot time init code relied on
for mounting the root filesystem.

Now, most people never noticed this, because not only is it
timing-dependent, but modern distributions all use initrd.  So the root
filesystem isn't actually on a disk at all.  And then before they
actually mount the final disk filesystem, they will have loaded the
scsi-wait-scan module, which not only does the expected
wait_for_device_probe(), but also does scsi_complete_async_scans().

[ Side note: scsi_complete_async_scans() had also been partially broken,
  but that was fixed in commit 43a8d39d01 ("fix async probe
  regression"), so that same commit a7a20d1039 had actually broken
  setups even if you used scsi-wait-scan explicitly ]

Solve this problem by just moving the scsi_complete_async_scans() call
into wait_for_device_probe().  Everybody who wants to wait for device
probing to finish really wants the SCSI probing to complete, so there's
no reason not to do this.

So now "wait_for_device_probe()" really does what the name implies, and
properly waits for device probing to finish.  This also removes the now
unnecessary extra calls to scsi_complete_async_scans().

Reported-and-tested-by: Artem S. Tashkinov <t.artem@mailcity.com>
Cc: Dan Williams <dan.j.williams@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: James Bottomley <jbottomley@parallels.com>
Cc: Borislav Petkov <bp@amd64.org>
Cc: linux-scsi <linux-scsi@vger.kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2012-07-18 18:15:46 -07:00
parent e2f3b78557
commit eea03c20ae
5 changed files with 2 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/base/dd.c
View File

@ -24,6 +24,7 @@
#include <linux/wait.h>
#include <linux/async.h>
#include <linux/pm_runtime.h>
#include <scsi/scsi_scan.h>
#include "base.h"
#include "power/power.h"
@ -332,6 +333,7 @@ void wait_for_device_probe(void)
/* wait for the known devices to complete their probing */
wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
async_synchronize_full();
scsi_complete_async_scans();
}
EXPORT_SYMBOL_GPL(wait_for_device_probe);

5
drivers/scsi/scsi_wait_scan.c
View File

@ -22,11 +22,6 @@ static int __init wait_scan_init(void)
* and might not yet have reached the scsi async scanning
*/
wait_for_device_probe();
/*
* and then we wait for the actual asynchronous scsi scan
* to finish.
*/
scsi_complete_async_scans();
return 0;
}

2
include/linux/device.h
View File

@ -865,8 +865,6 @@ extern int (*platform_notify_remove)(struct device *dev);
extern struct device *get_device(struct device *dev);
extern void put_device(struct device *dev);
extern void wait_for_device_probe(void);
#ifdef CONFIG_DEVTMPFS
extern int devtmpfs_create_node(struct device *dev);
extern int devtmpfs_delete_node(struct device *dev);

8
kernel/power/hibernate.c
View File

@ -27,7 +27,6 @@
#include <linux/syscore_ops.h>
#include <linux/ctype.h>
#include <linux/genhd.h>
#include <scsi/scsi_scan.h>
#include "power.h"
@ -748,13 +747,6 @@ static int software_resume(void)
async_synchronize_full();
}
/*
* We can't depend on SCSI devices being available after loading
* one of their modules until scsi_complete_async_scans() is
* called and the resume device usually is a SCSI one.
*/
scsi_complete_async_scans();
swsusp_resume_device = name_to_dev_t(resume_file);
if (!swsusp_resume_device) {
error = -ENODEV;

2
kernel/power/user.c
View File

@ -24,7 +24,6 @@
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/freezer.h>
#include <scsi/scsi_scan.h>
#include <asm/uaccess.h>
@ -84,7 +83,6 @@ static int snapshot_open(struct inode *inode, struct file *filp)
* appear.
*/
wait_for_device_probe();
scsi_complete_async_scans();
data->swap = -1;
data->mode = O_WRONLY;