linux-kernel - Re: [PATCH 3/4] selftests: ublk: kublk: ignore SIGCHLD

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Message-ID: <Z-NzLbW0nAIAUdIN@fedora>
Date: Wed, 26 Mar 2025 11:23:25 +0800
From: Ming Lei <ming.lei@...hat.com>
To: Uday Shankar <ushankar@...estorage.com>
Cc: Shuah Khan <shuah@...nel.org>, Jens Axboe <axboe@...nel.dk>,
	linux-block@...r.kernel.org, linux-kselftest@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] selftests: ublk: kublk: ignore SIGCHLD

On Tue, Mar 25, 2025 at 04:19:33PM -0600, Uday Shankar wrote:
> SIGCHLD from exiting children can arrive during io_uring_wait_cqe and
> cause it to return early with -EINTR. Since we don't have a handler for

Probably -EINTR needs to be handled, and libublksrv retry in case of -EINTR.

> SIGCHLD, avoid this issue by ignoring SIGCHLD.
> 
> Signed-off-by: Uday Shankar <ushankar@...estorage.com>
> ---
>  tools/testing/selftests/ublk/kublk.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
> index ded1b93e7913011499ae5dae7b40f0e425982ee4..064a5bb6f12f35892065b8dfacb6f57f6fc16aee 100644
> --- a/tools/testing/selftests/ublk/kublk.c
> +++ b/tools/testing/selftests/ublk/kublk.c
> @@ -890,6 +890,7 @@ static int cmd_dev_add(struct dev_ctx *ctx)
>  		exit(-1);
>  	}
>  
> +	signal(SIGCHLD, SIG_IGN);

Reviewed-by: Ming Lei <ming.lei@...hat.com>

BTW, the SIGCHLD signal is ignored by default, looks it is good
to do it explicitly, if the -EINTR from io_uring_enter() can be avoided
in this way.


Thanks,
Ming