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SubjectRe: [External] [PATCH] io_uring: Fix use of uninitialized ret in io_eventfd_register()
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On 07/02/2022 16:24, Nathan Chancellor wrote:
> Clang warns:
>
> fs/io_uring.c:9396:9: warning: variable 'ret' is uninitialized when used here [-Wuninitialized]
> return ret;
> ^~~
> fs/io_uring.c:9373:13: note: initialize the variable 'ret' to silence this warning
> int fd, ret;
> ^
> = 0
> 1 warning generated.
>
> Just return 0 directly and reduce the scope of ret to the if statement,
> as that is the only place that it is used, which is how the function was
> before the fixes commit.
>
> Fixes: 1a75fac9a0f9 ("io_uring: avoid ring quiesce while registering/unregistering eventfd")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1579
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> fs/io_uring.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>

Thanks for pointing this out. Just for some background in earlier
revisions of the patch for "io_uring: avoid ring quiesce while
registering/unregistering eventfd" the error return part was being
handled differently, but ended up looking similar to before in the final
revision that got merged, but i forgot to change this part back. Would
it be possible to fold the below diff into the patch as well Jens?
Thanks and sorry for missing this!

Regards,
Usama

> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 5479f0607430..7ef04bb66da1 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -9370,7 +9370,7 @@ static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg,
> {
> struct io_ev_fd *ev_fd;
> __s32 __user *fds = arg;
> - int fd, ret;
> + int fd;
>
> ev_fd = rcu_dereference_protected(ctx->io_ev_fd,
> lockdep_is_held(&ctx->uring_lock));
> @@ -9386,14 +9386,14 @@ static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg,
>
> ev_fd->cq_ev_fd = eventfd_ctx_fdget(fd);
> if (IS_ERR(ev_fd->cq_ev_fd)) {
> - ret = PTR_ERR(ev_fd->cq_ev_fd);
> + int ret = PTR_ERR(ev_fd->cq_ev_fd);
> kfree(ev_fd);
> return ret;
> }
> ev_fd->eventfd_async = eventfd_async;
>
> rcu_assign_pointer(ctx->io_ev_fd, ev_fd);
> - return ret;
> + return 0;
> }
>
> static void io_eventfd_put(struct rcu_head *rcu)
>
> base-commit: 88a0394bc27de2dd8a8715970f289c5627052532
>

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