[PATCH][BZ #12723] Fix pathconf and fpathconf on Linux

[Florian Weimer]

On 03/01/2013 03:13 PM, Siddhesh Poyarekar wrote:
> On 1 March 2013 19:38, Florian Weimer <fweimer@redhat.com> wrote:
>> I think both the patch and the original code are wrong because Linux does
>> not guarantee atomic delivery beyond PAGE_SIZE (at least that's how I read
>> the code).  So pathconf(_PC_PIPE_BUF) should return PAGE_SIZE
>> unconditionally.
>>
>> F_SETPIPE_SZ increases the amount of data which can ideally be written
>> without blocking, but not the size of atomically delivered chunks.
>>
>
> I had thought that too, but the pipe_write code seems to be synced
> with a mutex_lock() on the inode, which is why I figured that the
> writes may be atomic.

pipe_wait() is called from within the loop and drops the mutex temporarily.

-- 
Florian Weimer / Red Hat Product Security Team