linux-stable/block
Jens Axboe f3da54ba14 Fix race with shared tag queue maps
There's a race condition in blk_queue_end_tag() for shared tag maps,
users include stex (promise supertrak thingy) and qla2xxx.  The former
at least has reported bugs in this area, not sure why we haven't seen
any for the latter.  It could be because the window is narrow and that
other conditions in the qla2xxx code hide this.  It's a real bug,
though, as the stex smp users can attest.

We need to ensure two things - the tag bit clearing needs to happen
AFTER we cleared the tag pointer, as the tag bit clearing/setting is
what protects this map.  Secondly, we need to ensure that the visibility
of the tag pointer and tag bit clear are ordered properly.

[ I removed the SMP barriers - "test_and_clear_bit()" already implies
  all the required barriers.  -- Linus ]

Also see http://bugzilla.kernel.org/show_bug.cgi?id=7842

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-09-13 08:20:25 -07:00
..
as-iosched.c [BLOCK] Get rid of request_queue_t typedef 2007-07-24 09:28:11 +02:00
blktrace.c blktrace: use cpu_clock() instead of sched_clock() 2007-07-27 08:08:24 +02:00
bsg.c [SCSI] bsg: update sg_io_v4 structure 2007-07-31 10:43:05 -05:00
cfq-iosched.c [BLOCK] Get rid of request_queue_t typedef 2007-07-24 09:28:11 +02:00
deadline-iosched.c [BLOCK] Get rid of request_queue_t typedef 2007-07-24 09:28:11 +02:00
elevator.c [BLOCK] Get rid of request_queue_t typedef 2007-07-24 09:28:11 +02:00
genhd.c unregister_blkdev(): return void 2007-07-17 10:23:03 -07:00
ioctl.c mm: remove destroy_dirty_buffers from invalidate_bdev() 2007-05-07 12:12:55 -07:00
Kconfig [SCSI] bsg: Fix build for CONFIG_BLOCK=n 2007-07-28 10:56:06 -04:00
Kconfig.iosched update I/O sched Kconfig help texts - CFQ is now default, not AS. 2007-02-17 20:08:22 +01:00
ll_rw_blk.c Fix race with shared tag queue maps 2007-09-13 08:20:25 -07:00
Makefile bsg: support for full generic block layer SG v3 2007-07-16 08:52:44 +02:00
noop-iosched.c [BLOCK] Get rid of request_queue_t typedef 2007-07-24 09:28:11 +02:00
scsi_ioctl.c [BLOCK] Get rid of request_queue_t typedef 2007-07-24 09:28:11 +02:00