Re: [PATCH] Use ERESTARTNOHAND if poll() is interrupted by a signal

Andrew Morton wrote:

On Sun, 29 Jul 2007 19:05:05 +0200
Manfred Spraul <[email protected]> wrote:

Hi Andrew,

poll() returns -EINTR if a signal is pending.
EINTR is a bad choice: it means that poll returns to user space if the
task is stopped by SIGSTOP/SIGCONT or by the freezer.
select() and ppoll() both use ERESTARTNOHAND, this avoids a return to
user space for signals that are handled by the kernel.

The patch switches poll() to ERESTARTNOHAND.
Tested with FC6. Patch against 2.6.23-rc1-mm1.

hm.  Is this a fix against
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.23-rc1/2.6.23-rc1-mm1/broken-out/do_poll-return-eintr-when-signalled.patch
only, or does mainline also need fixing?

Mainline has the same problem: poll() returns to user space if it's interrupted by SIGSTOP/SIGCONT.

I guess the consequences of the thing-which-this-fixes aren't huge, s I ca
queue this up for 2.6.24, after Oleg's
do_poll-return-eintr-when-signalled.patch?

Yes, please queue it: most/all linux versions show this behavior. Additionally, poll() is usually called in a loop and a spurious wakeup has no consequences.

--
   Manfred
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