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| author | Oleg Nesterov <oleg@tv-sign.ru> | 2006-08-21 08:34:15 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@suse.de> | 2006-08-21 08:34:15 +0200 |
| commit | 9f83e45eb54fc7198dc59fc63255341851ba4c48 (patch) | |
| tree | 3874581e08052b7f37f164110b3bd44ae5eff291 | |
| parent | 78bd4d484f81a611ef6ff02f909e576cb9aac7f2 (diff) | |
| download | linux-stable-9f83e45eb54fc7198dc59fc63255341851ba4c48.tar.gz linux-stable-9f83e45eb54fc7198dc59fc63255341851ba4c48.tar.bz2 linux-stable-9f83e45eb54fc7198dc59fc63255341851ba4c48.zip | |
[PATCH] Fix current_io_context() vs set_task_ioprio() race
I know nothing about io scheduler, but I suspect set_task_ioprio() is not safe.
current_io_context() initializes "struct io_context", then sets ->io_context.
set_task_ioprio() running on another cpu may see the changes out of order, so
->set_ioprio(ioc) may use io_context which was not initialized properly.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Jens Axboe <axboe@suse.de>
| -rw-r--r-- | block/ll_rw_blk.c | 2 | ||||
| -rw-r--r-- | fs/ioprio.c | 3 |
2 files changed, 5 insertions, 0 deletions
diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index 61d6b3c65b66..ddd9253f9d55 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -3628,6 +3628,8 @@ struct io_context *current_io_context(gfp_t gfp_flags) ret->nr_batch_requests = 0; /* because this is 0 */ ret->aic = NULL; ret->cic_root.rb_node = NULL; + /* make sure set_task_ioprio() sees the settings above */ + smp_wmb(); tsk->io_context = ret; } diff --git a/fs/ioprio.c b/fs/ioprio.c index 3db31038e9ab..06578311c63f 100644 --- a/fs/ioprio.c +++ b/fs/ioprio.c @@ -44,6 +44,9 @@ static int set_task_ioprio(struct task_struct *task, int ioprio) task->ioprio = ioprio; ioc = task->io_context; + /* see wmb() in current_io_context() */ + smp_read_barrier_depends(); + if (ioc && ioc->set_ioprio) ioc->set_ioprio(ioc, ioprio); |