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Commit eea03c20 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Make wait_for_device_probe() also do scsi_complete_async_scans() 



Commit a7a20d10 ("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 43a8d39d ("fix async probe
  regression"), so that same commit a7a20d10 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: default avatarArtem 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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e2f3b785

drivers/base/dd.c

+2 −0
Original line number Diff line number Diff line
@@ -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);

drivers/scsi/scsi_wait_scan.c

+0 −5
Original line number Diff line number Diff line
@@ -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;

}

include/linux/device.h

+0 −2
Original line number Diff line number Diff line
@@ -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);

kernel/power/hibernate.c

+0 −8
Original line number Diff line number Diff line
@@ -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;

kernel/power/user.c

+0 −2
Original line number Diff line number Diff line
@@ -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;