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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>		14 years ago
..
Kconfig	kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT	14 years ago
Kconfig.iosched	blk-cgroup: config options re-arrangement	15 years ago
Makefile	Merge branch 'for-2.6.37/barrier' of git://git.kernel.dk/linux-2.6-block	14 years ago
blk-cgroup.c	blk-cgroup: Allow creation of hierarchical cgroups	14 years ago
blk-cgroup.h	blkio-throttle: limit max iops value to UINT_MAX	14 years ago
blk-core.c	block: add @force_kblockd to __blk_run_queue()	14 years ago
blk-exec.c	block: Prevent hang_check firing during long I/O	14 years ago
blk-flush.c	block: blk-flush shouldn't call directly into q->request_fn() __blk_run_queue()	14 years ago
blk-integrity.c	block: Fix double free in blk_integrity_unregister	14 years ago
blk-ioc.c	block: Clean up exit_io_context() source code.	14 years ago
blk-iopoll.c	…
blk-lib.c	block: fix mis-synchronisation in blkdev_issue_zeroout()	14 years ago
blk-map.c	block: check for proper length of iov entries earlier in blk_rq_map_user_iov()	14 years ago
blk-merge.c	Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block	14 years ago
blk-settings.c	block: max hardware sectors limit wrapper	14 years ago
blk-softirq.c	…
blk-sysfs.c	block: Deprecate QUEUE_FLAG_CLUSTER and use queue_limits instead	14 years ago
blk-tag.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	15 years ago
blk-throttle.c	blk-throttle: Do not use kblockd workqueue for throtl work	14 years ago
blk-timeout.c	block: ensure jiffies wrap is handled correctly in blk_rq_timed_out_timer	15 years ago
blk.h	Revert "block: fix accounting bug on cross partition merges"	14 years ago
bsg.c	[SCSI] bsg: correct fault if queue object removed while dev_t open	14 years ago
cfq-iosched.c	block: add @force_kblockd to __blk_run_queue()	14 years ago
cfq.h	blk-cgroup: Prepare the base for supporting more than one IO control policies	15 years ago
compat_ioctl.c	BKL: remove extraneous #include <smp_lock.h>	14 years ago
deadline-iosched.c	…
elevator.c	block: add @force_kblockd to __blk_run_queue()	14 years ago
genhd.c	Fix over-zealous flush_disk when changing device size.	14 years ago
ioctl.c	block: fix refcounting in BLKBSZSET	14 years ago
noop-iosched.c	include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h	15 years ago
scsi_ioctl.c	block: take care not to overflow when calculating total iov length	14 years ago