diff options
| author | Hagar Hemdan <hagarhem@amazon.com> | 2024-06-04 13:05:27 +0000 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2024-06-04 07:39:17 -0600 |
| commit | 73254a297c2dd094abec7c9efee32455ae875bdf (patch) | |
| tree | cc04d94e87d77ad05f00a22e03697fcf9520e7a3 | |
| parent | 91215f70ea8541e9011c0b48f8b59b9e0ce6953b (diff) | |
io_uring: fix possible deadlock in io_register_iowq_max_workers()
The io_register_iowq_max_workers() function calls io_put_sq_data(),
which acquires the sqd->lock without releasing the uring_lock.
Similar to the commit 009ad9f0c6ee ("io_uring: drop ctx->uring_lock
before acquiring sqd->lock"), this can lead to a potential deadlock
situation.
To resolve this issue, the uring_lock is released before calling
io_put_sq_data(), and then it is re-acquired after the function call.
This change ensures that the locks are acquired in the correct
order, preventing the possibility of a deadlock.
Suggested-by: Maximilian Heyne <mheyne@amazon.de>
Signed-off-by: Hagar Hemdan <hagarhem@amazon.com>
Link: https://lore.kernel.org/r/20240604130527.3597-1-hagarhem@amazon.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | io_uring/register.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/io_uring/register.c b/io_uring/register.c index ef8c908346a4..c0010a66a6f2 100644 --- a/io_uring/register.c +++ b/io_uring/register.c @@ -355,8 +355,10 @@ static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx, } if (sqd) { + mutex_unlock(&ctx->uring_lock); mutex_unlock(&sqd->lock); io_put_sq_data(sqd); + mutex_lock(&ctx->uring_lock); } if (copy_to_user(arg, new_count, sizeof(new_count))) @@ -380,8 +382,10 @@ static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx, return 0; err: if (sqd) { + mutex_unlock(&ctx->uring_lock); mutex_unlock(&sqd->lock); io_put_sq_data(sqd); + mutex_lock(&ctx->uring_lock); } return ret; } |