Messages in this thread | | | From | Neil Brown <> | Date | Thu, 19 Jun 2008 12:29:16 +1000 | Subject | Re: [PATCH - take 2] knfsd: nfsd: Handle ERESTARTSYS from syscalls. |
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On Wednesday June 18, jlayton@redhat.com wrote: > > No objection to the patch, but what signal was being sent to nfsd when > you saw this? If it's anything but a SIGKILL, then I wonder if we have > a race that we need to deal with. My understanding is that we have nfsd > flip between 2 sigmasks to prevent anything but a SIGKILL from being > delivered while we're handling the local filesystem operation.
SuSE /etc/init.d/nfsserver does
killproc -n -KILL nfsd
so it looks like a SIGKILL.
> > From nfsd(): > > ----------[snip]----------- > sigprocmask(SIG_SETMASK, &shutdown_mask, NULL); > > /* > * Find a socket with data available and call its > * recvfrom routine. > */ > while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN) > ; > if (err < 0) > break; > update_thread_usage(atomic_read(&nfsd_busy)); > atomic_inc(&nfsd_busy); > > /* Lock the export hash tables for reading. */ > exp_readlock(); > > /* Process request with signals blocked. */ > sigprocmask(SIG_SETMASK, &allowed_mask, NULL); > > svc_process(rqstp); > > ----------[snip]----------- > > What happens if this catches a SIGINT after the err<0 check, but before > the mask is set to allowed_mask? Does svc_process() then get called with > a signal pending?
Yes, I suspect it does.
I wonder why we have all this mucking about this signal masks anyway. Anyone have any ideas about what it actually achieves?
NeilBrown
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