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io_uring: fix possible deadlock in io_register_iowq_max_workers()
[ Upstream commit73254a297c
] 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 commit009ad9f0c6
("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> Signed-off-by: Sasha Levin <sashal@kernel.org>
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parent
9f9c79d8e5
commit
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@ -355,8 +355,10 @@ static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
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}
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if (sqd) {
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mutex_unlock(&ctx->uring_lock);
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mutex_unlock(&sqd->lock);
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io_put_sq_data(sqd);
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mutex_lock(&ctx->uring_lock);
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}
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if (copy_to_user(arg, new_count, sizeof(new_count)))
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@ -381,8 +383,10 @@ static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
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return 0;
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err:
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if (sqd) {
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mutex_unlock(&ctx->uring_lock);
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mutex_unlock(&sqd->lock);
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io_put_sq_data(sqd);
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mutex_lock(&ctx->uring_lock);
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}
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return ret;
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}
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