mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-12 05:48:39 +08:00
f1a4f4d35f
* cfq_cic_lookup() may be called without queue_lock and multiple tasks can execute it simultaneously for the same shared ioc. Nothing prevents them racing each other and trying to drop the same dead cic entry multiple times. * smp_wmb() in cfq_exit_cic() doesn't really do anything and nothing prevents cfq_cic_lookup() seeing stale cic->key. This usually doesn't blow up because by the time cic is exited, all requests have been drained and new requests are terminated before going through elevator. However, it can still be triggered by plug merge path which doesn't grab queue_lock and thus can't check DEAD state reliably. This patch updates lookup locking such that, * Lookup is always performed under queue_lock. This doesn't add any more locking. The only issue is cfq_allow_merge() which can be called from plug merge path without holding any lock. For now, this is worked around by using cic of the request to merge into, which is guaranteed to have the same ioc. For longer term, I think it would be best to separate out plug merge method from regular one. * Spurious ioc->lock locking around cic lookup hint assignment dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> |
||
|---|---|---|
| .. | ||
| blk-cgroup.c | ||
| blk-cgroup.h | ||
| blk-core.c | ||
| blk-exec.c | ||
| blk-flush.c | ||
| blk-integrity.c | ||
| blk-ioc.c | ||
| blk-iopoll.c | ||
| blk-lib.c | ||
| blk-map.c | ||
| blk-merge.c | ||
| blk-settings.c | ||
| blk-softirq.c | ||
| blk-sysfs.c | ||
| blk-tag.c | ||
| blk-throttle.c | ||
| blk-timeout.c | ||
| blk.h | ||
| bsg-lib.c | ||
| bsg.c | ||
| cfq-iosched.c | ||
| cfq.h | ||
| compat_ioctl.c | ||
| deadline-iosched.c | ||
| elevator.c | ||
| genhd.c | ||
| ioctl.c | ||
| Kconfig | ||
| Kconfig.iosched | ||
| Makefile | ||
| noop-iosched.c | ||
| scsi_ioctl.c | ||