diff options
| author | Ed Cashin <ecashin@coraid.com> | 2012-12-18 04:04:09 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-18 05:15:25 +0400 |
| commit | e52a29326462badd9ceec90a9eb2ac2a8550e02e (patch) | |
| tree | 28d732cd1bbae93d3e2b490127a6afbc0af279c8 /drivers/block/aoe/aoe.h | |
| parent | bbb44e30d07fdc111e34a5ec935b57521cea9499 (diff) | |
| download | linux-e52a29326462badd9ceec90a9eb2ac2a8550e02e.tar.xz | |
aoe: avoid races between device destruction and discovery
This change avoids a race that could result in a NULL pointer derference
following a WARNing from kobject_add_internal, "don't try to register
things with the same name in the same directory."
The problem was found with a test that forgets and discovers an
aoe device in a loop:
while test ! -r /tmp/stop; do
aoe-flush -a
aoe-discover
done
The race was between aoedev_flush taking aoedevs out of the devlist,
allowing a new discovery of the same AoE target to take place before the
driver gets around to calling sysfs_remove_group. Fixing that one
revealed another race between do_open and add_disk, and this patch avoids
that, too.
The fix required some care, because for flushing (forgetting) an aoedev,
some of the steps must be performed under lock and some must be able to
sleep. Also, for discovering a new aoedev, some steps might sleep.
The check for a bad aoedev pointer remains from a time when about half of
this patch was done, and it was possible for the
bdev->bd_disk->private_data to become corrupted. The check should be
removed eventually, but it is not expected to add significant overhead,
occurring in the aoeblk_open routine.
Signed-off-by: Ed Cashin <ecashin@coraid.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/block/aoe/aoe.h')
| -rw-r--r-- | drivers/block/aoe/aoe.h | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/block/aoe/aoe.h b/drivers/block/aoe/aoe.h index b6d2b16358be..d50e9455b937 100644 --- a/drivers/block/aoe/aoe.h +++ b/drivers/block/aoe/aoe.h @@ -74,8 +74,11 @@ enum { DEVFL_TKILL = (1<<1), /* flag for timer to know when to kill self */ DEVFL_EXT = (1<<2), /* device accepts lba48 commands */ DEVFL_GDALLOC = (1<<3), /* need to alloc gendisk */ - DEVFL_KICKME = (1<<4), /* slow polling network card catch */ - DEVFL_NEWSIZE = (1<<5), /* need to update dev size in block layer */ + DEVFL_GD_NOW = (1<<4), /* allocating gendisk */ + DEVFL_KICKME = (1<<5), /* slow polling network card catch */ + DEVFL_NEWSIZE = (1<<6), /* need to update dev size in block layer */ + DEVFL_FREEING = (1<<7), /* set when device is being cleaned up */ + DEVFL_FREED = (1<<8), /* device has been cleaned up */ }; enum { |