[lxc-devel] [PATCH] exclude non-existing signals from the loop

[S.Çağlar Onur]

On Fri, Jan 17, 2014 at 9:24 AM, Serge Hallyn <serge.hallyn at ubuntu.com> 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?
>
> 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

Yep make sense and much better than hardcoding 32 and 33 in the loop as I did :)

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-- 
S.Çağlar Onur <caglar at 10ur.org>