Lukas Czerner 0aeea18964 block: fix mis-synchronisation in blkdev_issue_zeroout() ... BZ29402 https://bugzilla.kernel.org/show_bug.cgi?id=29402 We can hit serious mis-synchronization in bio completion path of blkdev_issue_zeroout() leading to a panic. The problem is that when we are going to wait_for_completion() in blkdev_issue_zeroout() we check if the bb.done equals issued (number of submitted bios). If it does, we can skip the wait_for_completition() and just out of the function since there is nothing to wait for. However, there is a ordering problem because bio_batch_end_io() is calling atomic_inc(&bb->done) before complete(), hence it might seem to blkdev_issue_zeroout() that all bios has been completed and exit. At this point when bio_batch_end_io() is going to call complete(bb->wait), bb and wait does not longer exist since it was allocated on stack in blkdev_issue_zeroout() ==> panic! (thread 1) (thread 2) bio_batch_end_io() blkdev_issue_zeroout() if(bb) { ... if (bb->end_io) ... bb->end_io(bio, err); ... atomic_inc(&bb->done); ... ... while (issued != atomic_read(&bb.done)) ... (let issued == bb.done) ... (do the rest of the function) ... return ret; complete(bb->wait); ^^^^^^^^ panic We can fix this easily by simplifying bio_batch and completion counting. Also remove bio_end_io_t *end_io since it is not used. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Reported-by: Eric Whitney <eric.whitney@hp.com> Tested-by: Eric Whitney <eric.whitney@hp.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> CC: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>		2011-03-11 15:36:08 +01:00
..
blk-cgroup.c
blk-cgroup.h
blk-core.c	block: add @force_kblockd to __blk_run_queue()	2011-03-02 08:48:05 -05:00
blk-exec.c
blk-flush.c	block: blk-flush shouldn't call directly into q->request_fn() __blk_run_queue()	2011-03-02 08:48:06 -05:00
blk-integrity.c
blk-ioc.c
blk-iopoll.c
blk-lib.c	block: fix mis-synchronisation in blkdev_issue_zeroout()	2011-03-11 15:36:08 +01:00
blk-map.c
blk-merge.c
blk-settings.c
blk-softirq.c
blk-sysfs.c
blk-tag.c
blk-throttle.c	blk-throttle: Do not use kblockd workqueue for throtl work	2011-03-01 13:41:53 -05:00
blk-timeout.c
blk.h
bsg.c
cfq-iosched.c	block: add @force_kblockd to __blk_run_queue()	2011-03-02 08:48:05 -05:00
cfq.h
compat_ioctl.c
deadline-iosched.c
elevator.c	block: add @force_kblockd to __blk_run_queue()	2011-03-02 08:48:05 -05:00
genhd.c	Fix over-zealous flush_disk when changing device size.	2011-02-24 17:25:47 +11:00
ioctl.c	block: fix refcounting in BLKBSZSET	2011-02-24 08:54:21 -08:00
Kconfig	kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT	2011-01-20 17:02:05 -08:00
Kconfig.iosched
Makefile
noop-iosched.c
scsi_ioctl.c