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authorHagar Hemdan <hagarhem@amazon.com>2024-06-04 13:05:27 +0000
committerJens Axboe <axboe@kernel.dk>2024-06-04 07:39:17 -0600
commit73254a297c2dd094abec7c9efee32455ae875bdf (patch)
treecc04d94e87d77ad05f00a22e03697fcf9520e7a3 /io_uring
parent91215f70ea8541e9011c0b48f8b59b9e0ce6953b (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>
Diffstat (limited to 'io_uring')
-rw-r--r--io_uring/register.c4
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;
}