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| author | Jens Axboe <axboe@kernel.dk> | 2022-12-21 15:05:09 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2022-12-21 16:43:53 +0100 |
| commit | 52ea806ad983490b3132a9e526e11a10dc2fd10c (patch) | |
| tree | c1a8029e933faa2d1091d18786b466a63e061b28 /io_uring | |
| parent | MAINTAINERS: io_uring: Add include/trace/events/io_uring.h (diff) | |
| download | linux-52ea806ad983490b3132a9e526e11a10dc2fd10c.tar.xz linux-52ea806ad983490b3132a9e526e11a10dc2fd10c.zip | |
io_uring: finish waiting before flushing overflow entries
If we have overflow entries being generated after we've done the
initial flush in io_cqring_wait(), then we could be flushing them in the
main wait loop as well. If that's done after having added ourselves
to the cq_wait waitqueue, then the task state can be != TASK_RUNNING
when we enter the overflow flush.
Check for the need to overflow flush, and finish our wait cycle first
if we have to do so.
Reported-and-tested-by: syzbot+cf6ea1d6bb30a4ce10b2@syzkaller.appspotmail.com
Link: https://lore.kernel.org/io-uring/000000000000cb143a05f04eee15@google.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/io_uring.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index ff2bbac1a10f..ac5d39eeb3d1 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -677,16 +677,20 @@ static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx) io_cq_unlock_post(ctx); } +static void io_cqring_do_overflow_flush(struct io_ring_ctx *ctx) +{ + /* iopoll syncs against uring_lock, not completion_lock */ + if (ctx->flags & IORING_SETUP_IOPOLL) + mutex_lock(&ctx->uring_lock); + __io_cqring_overflow_flush(ctx); + if (ctx->flags & IORING_SETUP_IOPOLL) + mutex_unlock(&ctx->uring_lock); +} + static void io_cqring_overflow_flush(struct io_ring_ctx *ctx) { - if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)) { - /* iopoll syncs against uring_lock, not completion_lock */ - if (ctx->flags & IORING_SETUP_IOPOLL) - mutex_lock(&ctx->uring_lock); - __io_cqring_overflow_flush(ctx); - if (ctx->flags & IORING_SETUP_IOPOLL) - mutex_unlock(&ctx->uring_lock); - } + if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)) + io_cqring_do_overflow_flush(ctx); } void __io_put_task(struct task_struct *task, int nr) @@ -2549,7 +2553,10 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events, trace_io_uring_cqring_wait(ctx, min_events); do { - io_cqring_overflow_flush(ctx); + if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)) { + finish_wait(&ctx->cq_wait, &iowq.wq); + io_cqring_do_overflow_flush(ctx); + } prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq, TASK_INTERRUPTIBLE); ret = io_cqring_wait_schedule(ctx, &iowq, timeout); |