Re: [PATCH RFC 0/3] A few round_pipe_size() and pipe-max-size fixups

[Randy Dunlap]

On 09/14/17 06:26, Michael Kerrisk (man-pages) wrote:
> Hello Joe,
> 
> On 5 September 2017 at 16:44, Joe Lawrence <joe.lawrence@xxxxxxxxxx> wrote:
>> While backporting Michael's "pipe: fix limit handling" [1] patchset to a
>> distro-kernel, Mikulas noticed that current upstream pipe limit handling
>> contains a few problems:
>>
>>   1 - round_pipe_size() nr_pages overflow on 32bit:  this would
>>       subsequently try roundup_pow_of_two(0), which is undefined.

Hi,
Sorry I missed the initial posting of this.

The man page for F_SETPIPE_SZ (http://man7.org/linux/man-pages/man2/fcntl.2.html)
says:
"Attempts to set the pipe capacity below the page size are
silently rounded up to the page size."

That implies to me that setting pipe size to 0 would round up to PAGE_SIZE.
Doesn't patch 1/3 change that to return -EINVAL?


Otherwise all 3 patches look good to me.

thanks,
-- 
~Randy