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Message-ID: <4A796F27.9040003@redhat.com>
Date: Wed, 05 Aug 2009 19:38:15 +0800
From: Amerigo Wang <amwang@...hat.com>
To: Ingo Molnar <mingo@...e.hu>
CC: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
Al Viro <viro@...iv.linux.org.uk>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [Patch 1/2] ia32: use generic sys_pipe()
Ingo Molnar wrote:
> * Amerigo Wang <amwang@...hat.com> wrote:
>
>
>> As suggested by Al, it's better to use the generic sys_pipe() for
>> ia32.
>>
>> Signed-off-by: WANG Cong <amwang@...hat.com>
>> Cc: Ingo Molnar <mingo@...e.hu>
>> Cc: Al Viro <viro@...iv.linux.org.uk>
>> CC: Linus Torvalds <torvalds@...ux-foundation.org>
>>
>
>
>> --- a/arch/x86/ia32/sys_ia32.c
>> +++ b/arch/x86/ia32/sys_ia32.c
>> @@ -189,20 +189,6 @@ asmlinkage long sys32_mprotect(unsigned long start, size_t len,
>> return sys_mprotect(start, len, prot);
>> }
>>
>> -asmlinkage long sys32_pipe(int __user *fd)
>> -{
>> - int retval;
>> - int fds[2];
>> -
>> - retval = do_pipe_flags(fds, 0);
>> - if (retval)
>> - goto out;
>> - if (copy_to_user(fd, fds, sizeof(fds)))
>> - retval = -EFAULT;
>> -out:
>> - return retval;
>> -}
>>
>
> Please _ALWAYS_ mention the change in behavior in the changelog,
> just in case someone ends up bisecting it. I only found out when i
> reviewed the two syscalls out of caution.
>
> The syscall you remove kept stale fd's around in case of -EFAULT
> from copy_to_user(). The generic version does an explicit close of
> those files:
>
> sys_close(fd[0]);
> sys_close(fd[1]);
> error = -EFAULT;
>
> The generic version looks like the better choice to me but this
> difference should be mentioned in the changelog nevertheless, just
> in case some buggy app runs into this issue.
>
Hi, yes, exactly.
Thank you! I will be careful next time.
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