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Re: [PATCH] linux-user: Remove unnecessary static assert involving __SIG
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [PATCH] linux-user: Remove unnecessary static assert involving __SIGRTMAX |
Date: |
Wed, 26 May 2021 19:16:28 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 |
On 5/26/21 6:39 AM, Michael Forney wrote:
> Since "linux-user: fix use of SIGRTMIN" (6bc024e7), qemu removed
> use of __SIGRTMAX except for in this QEMU_BUILD_BUG_ON assert.
> Presumably, this check is to ensure that the loop in signal_table_init
> from SIGRTMIN to SIGRTMAX falls within the bounds of
> host_to_target_signal_table (_NSIG).
>
> However, _NSIG is already defined to be the one larger than the
> largest signal supported by the system (as specified in the upcoming
> POSIX revision[0]), so the check is unnecessary.
>
> musl libc does not define __SIGRTMAX, so removing this check fixes
> one of the last remaining errors when building qemu.
>
> [0] https://www.austingroupbugs.net/view.php?id=741
>
> Signed-off-by: Michael Forney <mforney@mforney.org>
> ---
> If you prefer, I can send an alternate patch to leave the
> QEMU_BUILD_BUG_ON, but guard it by #ifdef __SIGRTMAX.
This looks safer, personally I prefer, but let's see what the
maintainers prefer.
> linux-user/signal.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/linux-user/signal.c b/linux-user/signal.c
> index 9016896dcd..6f62f2b528 100644
> --- a/linux-user/signal.c
> +++ b/linux-user/signal.c
> @@ -38,7 +38,6 @@ static void host_signal_handler(int host_signum, siginfo_t
> *info,
> * Signal number 0 is reserved for use as kill(pid, 0), to test whether
> * a process exists without sending it a signal.
> */
> -QEMU_BUILD_BUG_ON(__SIGRTMAX + 1 != _NSIG);
> static uint8_t host_to_target_signal_table[_NSIG] = {
> [SIGHUP] = TARGET_SIGHUP,
> [SIGINT] = TARGET_SIGINT,
>