[lxc-devel] [PATCH] exclude non-existing signals from the loop
Stéphane Graber
stgraber at ubuntu.com
Fri Jan 17 17:31:15 UTC 2014
On Fri, Jan 17, 2014 at 12:17:55PM -0500, Michael H. Warfield wrote:
> On Fri, 2014-01-17 at 08:24 -0600, Serge Hallyn wrote:
> > Quoting Qiang Huang (h.huangqiang at huawei.com):
> > > On 2014/1/17 5:38, Serge Hallyn wrote:
> > > > Quoting S.Çağlar Onur (caglar at 10ur.org):
> > > >> On Thu, Jan 16, 2014 at 4:24 PM, Serge Hallyn <serge.hallyn at ubuntu.com> wrote:
> > > >>> Quoting S.Çağlar Onur (caglar at 10ur.org):
> > > >>>> 32 and 33 are not defined and causing sigaction to fail. "kill -l" shows following
> > > >>>> on my system
> > > >>>>
> > > >>>> 1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL 5) SIGTRAP
> > > >>>> 6) SIGABRT 7) SIGBUS 8) SIGFPE 9) SIGKILL 10) SIGUSR1
> > > >>>> 11) SIGSEGV 12) SIGUSR2 13) SIGPIPE 14) SIGALRM 15) SIGTERM
> > > >>>> 16) SIGSTKFLT 17) SIGCHLD 18) SIGCONT 19) SIGSTOP 20) SIGTSTP
> > > >>>> 21) SIGTTIN 22) SIGTTOU 23) SIGURG 24) SIGXCPU 25) SIGXFSZ
> > > >>>> 26) SIGVTALRM 27) SIGPROF 28) SIGWINCH 29) SIGIO 30) SIGPWR
> > > >>>> 31) SIGSYS 34) SIGRTMIN 35) SIGRTMIN+1 36) SIGRTMIN+2 37) SIGRTMIN+3
> > > >>>> 38) SIGRTMIN+4 39) SIGRTMIN+5 40) SIGRTMIN+6 41) SIGRTMIN+7 42) SIGRTMIN+8
> > > >>>> 43) SIGRTMIN+9 44) SIGRTMIN+10 45) SIGRTMIN+11 46) SIGRTMIN+12 47) SIGRTMIN+13
> > > >>>> 48) SIGRTMIN+14 49) SIGRTMIN+15 50) SIGRTMAX-14 51) SIGRTMAX-13 52) SIGRTMAX-12
> > > >>>> 53) SIGRTMAX-11 54) SIGRTMAX-10 55) SIGRTMAX-9 56) SIGRTMAX-8 57) SIGRTMAX-7
> > > >>>> 58) SIGRTMAX-6 59) SIGRTMAX-5 60) SIGRTMAX-4 61) SIGRTMAX-3 62) SIGRTMAX-2
> > > >>>> 63) SIGRTMAX-1 64) SIGRTMAX
> > > >>>>
> > > >>>> Signed-off-by: S.Çağlar Onur <caglar at 10ur.org>
> > > >>>
> > > >>> Odd... on my system NSIG is 32, so these should never hit (since it is
> > > >>> in a while i<NSIG loop)
> > > >>
> > > >> Printing NSIG via ERROR shows that its 64 on my system.
> > > >
> > > > So a header file is #defining NSIG, which is already defined to 32
> > > > in kernel headers, to _NSIG, which is 64.
> > > >
> > > > Looking around the current state of kernel headers, i wonder whether
> > > > we should imply use min(SIGRTMIN, NSIG).
> > >
> > > My box is x86_64, and I got the same result as S.Çağlar.
> > >
> > > People may use signal number bigger than SIGRTMIN, so min(SIGRTMIN, NSIG)
> > > would miss them. Isn't that cause any problems?
> > >
> > > Maybe we should just bypass there non-existent signals.
> >
> > If we could know on any system which signals to bypass that'd be
> > fine, but AFAICS we can't.
>
> > It sounds to me like we should simply ignore failure at sigaction like
> > we used to :) Something like below. Is that what you meant?
>
> That would make the most sense to me.
>
> What would be the downside to ignoring the failure? Are there any error
> condition which we should not ignore?
>
> The man page indicates that errno has two defined values on failure.
> Either EINVAL, meaning an invalid signal was specified and we SHOULD
> ignore it, or EFAULT indicating something wrong with the pointers passed
> to it, which indicates something seriously wrong in the code. That
> doesn't mean there might not be others that they didn't think to
> list... :-P
So maybe show the INFO on EINVAL and hard fail on anything else?
>
> > From 87319b691c8f65c7d61ee01e64707d0b59d11caa Mon Sep 17 00:00:00 2001
> > From: Serge Hallyn <serge.hallyn at ubuntu.com>
> > Date: Fri, 17 Jan 2014 08:23:18 -0600
> > Subject: [PATCH 1/1] lxc_init: don't fail on bad signals
> >
> > Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>
> > ---
> > src/lxc/lxc_init.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/src/lxc/lxc_init.c b/src/lxc/lxc_init.c
> > index a59dd9c..b86edf8 100644
> > --- a/src/lxc/lxc_init.c
> > +++ b/src/lxc/lxc_init.c
> > @@ -159,8 +159,7 @@ int main(int argc, char *argv[])
> > act.sa_flags = 0;
> > act.sa_handler = interrupt_handler;
> > if (sigaction(i, &act, NULL)) {
> > - SYSERROR("failed to sigaction");
> > - exit(EXIT_FAILURE);
> > + INFO ("failed to sigaction (%d)", i);
> > }
> > }
> >
> > --
> > 1.8.5.2
> >
> > _______________________________________________
> > lxc-devel mailing list
> > lxc-devel at lists.linuxcontainers.org
> > http://lists.linuxcontainers.org/listinfo/lxc-devel
> >
>
> --
> Michael H. Warfield (AI4NB) | (770) 978-7061 | mhw at WittsEnd.com
> /\/\|=mhw=|\/\/ | (678) 463-0932 | http://www.wittsend.com/mhw/
> NIC whois: MHW9 | An optimist believes we live in the best of all
> PGP Key: 0x674627FF | possible worlds. A pessimist is sure of it!
>
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--
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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