linux-kernel - Re: [PATCH] restart_syscall.2: SYNOPSIS: Fix restart

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Date:   Mon, 23 Nov 2020 22:53:13 +0100
From:   "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
To:     Alejandro Colomar <alx.manpages@...il.com>
Cc:     mtk.manpages@...il.com, linux-man@...r.kernel.org,
        linux-kernel@...r.kernel.org, libc-alpha@...rceware.org
Subject: Re: [PATCH] restart_syscall.2: SYNOPSIS: Fix restart_syscall() return
 type

Hi Alex,

On 11/23/20 9:34 PM, Alejandro Colomar wrote:
> The Linux kernel uses 'long' instead of 'int' for the return type.
> As glibc provides no wrapper, use the same types the kernel uses.
> 
> $ grep -rn 'SYSCALL_DEFINE.*(restart_syscall'
> kernel/signal.c:2891:SYSCALL_DEFINE0(restart_syscall)
> 
> $ sed -n 2891,2895p kernel/signal.c
> SYSCALL_DEFINE0(restart_syscall)
> {
> 	struct restart_block *restart = &current->restart_block;
> 	return restart->fn(restart);
> }
> 
> $ grep -rn 'struct restart_block {'
> include/linux/restart_block.h:25:struct restart_block {
> 
> $ sed -n 25,56p include/linux/restart_block.h
> struct restart_block {
> 	long (*fn)(struct restart_block *);
> 	union {
> 		/* For futex_wait and futex_wait_requeue_pi */
> 		struct {
> 			u32 __user *uaddr;
> 			u32 val;
> 			u32 flags;
> 			u32 bitset;
> 			u64 time;
> 			u32 __user *uaddr2;
> 		} futex;
> 		/* For nanosleep */
> 		struct {
> 			clockid_t clockid;
> 			enum timespec_type type;
> 			union {
> 				struct __kernel_timespec __user *rmtp;
> 				struct old_timespec32 __user *compat_rmtp;
> 			};
> 			u64 expires;
> 		} nanosleep;
> 		/* For poll */
> 		struct {
> 			struct pollfd __user *ufds;
> 			int nfds;
> 			int has_timeout;
> 			unsigned long tv_sec;
> 			unsigned long tv_nsec;
> 		} poll;
> 	};
> };
> 
> Signed-off-by: Alejandro Colomar <alx.manpages@...il.com>

Thanks! Patch applied.

Cheers,

Michael

> ---
>  man2/restart_syscall.2 | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/man2/restart_syscall.2 b/man2/restart_syscall.2
> index e7d96bd4d..21cc2df1d 100644
> --- a/man2/restart_syscall.2
> +++ b/man2/restart_syscall.2
> @@ -34,7 +34,7 @@
>  .SH NAME
>  restart_syscall \- restart a system call after interruption by a stop signal
>  .SH SYNOPSIS
> -.B int restart_syscall(void);
> +.B long restart_syscall(void);
>  .PP
>  .IR Note :
>  There is no glibc wrapper for this system call; see NOTES.
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/