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Message-ID: <f4a0e805-8b86-7579-84f3-6bb4b1d936d2@gmail.com>
Date: Fri, 27 Nov 2020 11:53:28 +0100
From: "Alejandro Colomar (man-pages)" <alx.manpages@...il.com>
To: "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
Cc: linux-man@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spu_create.2: Clarify that one of the prototypes is the
current one
Hi Michael,
On 11/27/20 11:43 AM, Michael Kerrisk (man-pages) wrote:
> Hi ALex,
>
> On 11/26/20 7:32 PM, Alejandro Colomar wrote:
>> The current Linux kernel only provides a definition of 'spu_create()'.
>> It has 4 parameters, the last being 'int neighbor_fd'.
>>
>> Before Linux 2.6.23, there was an older prototype,
>> which didn't have this last parameter.
>>
>> Move that old prototype to VERSIONS,
>> and keep the current one in SYNOPSIS.
>>
>> ......
>>
>> $ grep -rn "SYSCALL_DEFINE.(spu_create"
>> arch/powerpc/platforms/cell/spu_syscalls.c:56:
>> SYSCALL_DEFINE4(spu_create, const char __user *, name, unsigned int, flags,
>>
>> $ sed -n 56,/^}/p arch/powerpc/platforms/cell/spu_syscalls.c
>> SYSCALL_DEFINE4(spu_create, const char __user *, name, unsigned int, flags,
>> umode_t, mode, int, neighbor_fd)
>> {
>> long ret;
>> struct spufs_calls *calls;
>>
>> calls = spufs_calls_get();
>> if (!calls)
>> return -ENOSYS;
>>
>> if (flags & SPU_CREATE_AFFINITY_SPU) {
>> struct fd neighbor = fdget(neighbor_fd);
>> ret = -EBADF;
>> if (neighbor.file) {
>> ret = calls->create_thread(name, flags, mode, neighbor.file);
>> fdput(neighbor);
>> }
>> } else
>> ret = calls->create_thread(name, flags, mode, NULL);
>>
>> spufs_calls_put(calls);
>> return ret;
>> }
>>
>> $ git blame arch/powerpc/platforms/cell/spu_syscalls.c -L 56,/\)/
>> 1bc94226d5c64 (Al Viro 2011-07-26 16:50:23 -0400 56)
>> SYSCALL_DEFINE4(spu_create, const char __user *, name, unsigned int, flags,
>> 1bc94226d5c64 (Al Viro 2011-07-26 16:50:23 -0400 57)
>> umode_t, mode, int, neighbor_fd)
>>
>> $ git checkout 1bc94226d5c64~1
>> $ git blame arch/powerpc/platforms/cell/spu_syscalls.c -L /spu_create/,/\)/
>> 67207b9664a8d (Arnd Bergmann 2005-11-15 15:53:48 -0500 68)
>> asmlinkage long sys_spu_create(const char __user *name,
>> 8e68e2f248332 (Arnd Bergmann 2007-07-20 21:39:47 +0200 69)
>> unsigned int flags, mode_t mode, int neighbor_fd)
>>
>> $ git checkout 8e68e2f248332~1
>> $ git blame arch/powerpc/platforms/cell/spu_syscalls.c -L /spu_create/,/\)/
>> 67207b9664a8d (Arnd Bergmann 2005-11-15 15:53:48 -0500 36)
>> asmlinkage long sys_spu_create(const char __user *name,
>> 67207b9664a8d (Arnd Bergmann 2005-11-15 15:53:48 -0500 37)
>> unsigned int flags, mode_t mode)
>>
>> $ git describe --contains 8e68e2f248332
>> v2.6.23-rc1~195^2~7
>>
>> Signed-off-by: Alejandro Colomar <alx.manpages@...il.com>
>> ---
>> man2/spu_create.2 | 16 +++++++++++++---
>> 1 file changed, 13 insertions(+), 3 deletions(-)
>>
>> diff --git a/man2/spu_create.2 b/man2/spu_create.2
>> index 4e6f5d730..3eeafee56 100644
>> --- a/man2/spu_create.2
>> +++ b/man2/spu_create.2
>> @@ -30,9 +30,8 @@ spu_create \- create a new spu context
>> .B #include <sys/types.h>
>> .B #include <sys/spu.h>
>> .PP
>> -.BI "int spu_create(const char *" pathname ", int " flags ", mode_t " mode ");"
>> -.BI "int spu_create(const char *" pathname ", int " flags ", mode_t " mode ","
>> -.BI " int " neighbor_fd ");"
>> +.BI "int spu_create(const char *" pathname ", int " flags ", mode_t " mode ,
>> +.BI " int " neighbor_fd );
>> .fi
>> .PP
>> .IR Note :
>> @@ -247,6 +246,17 @@ By convention, it gets mounted in
>> The
>> .BR spu_create ()
>> system call was added to Linux in kernel 2.6.16.
>> +.PP
>> +.\" commit 8e68e2f248332a9c3fd4f08258f488c209bd3e0c
>> +Before Linux 2.6.23, the prototype for
>> +.BR spu_create ()
>> +was:
>> +.PP
>> +.in +4n
>> +.EX
>> +.BI "int spu_create(const char *" pathname ", int " flags ", mode_t " mode );
>> +.EE
>> +.in
>> .SH CONFORMING TO
>> This call is Linux-specific and implemented only on the PowerPC
>> architecture.
>
> Thanks for the detailed research.
You're welcome! :)
> The page was indeed a bit messy
> in explaining some details. I've instead opted for a different change;
> see below.
Looks good!
Cheers,
Alex
>
> Thanks,
>
> Michael
>
> diff --git a/man2/spu_create.2 b/man2/spu_create.2
> index 92f5fc304..f09d498ed 100644
> --- a/man2/spu_create.2
> +++ b/man2/spu_create.2
> @@ -30,7 +30,6 @@ spu_create \- create a new spu context
> .B #include <sys/types.h>
> .B #include <sys/spu.h>
> .PP
> -.BI "int spu_create(const char *" pathname ", int " flags ", mode_t " mode ");"
> .BI "int spu_create(const char *" pathname ", int " flags ", mode_t " mode ","
> .BI " int " neighbor_fd ");"
> .fi
> @@ -89,6 +88,12 @@ for a full list of the possible
> values.
> .PP
> The
> +.I neighbor_fd
> +is used only when the
> +.B SPU_CREATE_AFFINITY_SPU
> +flag is specified; see below.
> +.PP
> +The
> .I flags
> argument can be zero or any bitwise OR-ed
> combination of the following constants:
> @@ -264,6 +269,14 @@ See
> .UR http://www.bsc.es\:/projects\:/deepcomputing\:/linuxoncell/
> .UE
> for the recommended libraries.
> +.PP
> +Prior to the addition of the
> +.B SPU_CREATE_AFFINITY_SPU
> +flag in Linux 2.6.23, the
> +.BR spu_create ()
> +system call took only three arguments (i.e., there was no
> +.I neighbor_fd
> +argument).
> .SH EXAMPLES
> See
> .BR spu_run (2)
>
>
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