Messages in this thread | | | Date | Tue, 31 Jul 2007 04:18:47 +0400 | From | Oleg Nesterov <> | Subject | Re: [PATCH] Use ERESTARTNOHAND if poll() is interrupted by a signal |
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On 07/31, Oleg Nesterov wrote: > > > Manfred Spraul <manfred@colorfullife.com> wrote: > > > > > 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. > > > > > --- 2.6/fs/select.c 2007-07-28 20:31:51.000000000 +0200 > > > +++ build-2.6/fs/select.c 2007-07-28 21:21:52.000000000 +0200 > > > @@ -621,7 +621,7 @@ static int do_poll(unsigned int nfds, s > > > if (!count) { > > > count = wait->error; > > > if (signal_pending(current)) > > > - count = -EINTR; > > > + count = -ERESTARTNOHAND; > > I am not sure. This means we restart sys_poll() with the same timeout > if there is no pending signal. I think we need ERESTART_RESTARTBLOCK > logic.
Forgot to mention, sys_select() can use ERESTARTNOHAND because it modifies "struct timeval __user *tvp" before return, but sys_poll() gets timeout_msecs by value.
Oleg.
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