2020-11-23 20:37:27

by Alejandro Colomar

Subject: [PATCH] restart_syscall.2: SYNOPSIS: Fix restart_syscall() return type

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 <[email protected]>
---
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.
--
2.29.2

2020-11-23 21:58:01

by Michael Kerrisk (man-pages)

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 <[email protected]>

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/