Re: [RFC PATCH] kernel/signal.c: avoid BUG_ON with SIG128 (MIPS)

From: Denys Vlasenko
Date: Fri Jun 28 2013 - 16:04:10 EST


On Wednesday 29 May 2013 23:56, James Hogan wrote:
> On 29 May 2013 18:36, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> > On 05/29, David Daney wrote:
> >>
> >> On 05/29/2013 10:01 AM, James Hogan wrote:
> >>> MIPS has 128 signals, the highest of which has the number 128. The
> >>
> >> I wonder if we should change the ABI and reduce the number of signals to
> >> 127 instead of this patch.
> >
> > Same thoughts...
>
> I'll give it a try. I wouldn't have thought it'd break anything, but
> you never know. glibc (incorrectly) sets [__]SIGRTMAX to 127 already.
> On the other hand uClibc sets it to 128, so anything built against
> uClibc that uses signals SIGRTMAX-n (where n may be 0) or uses an
> excessive number of rt signals starting from SIGRTMIN (sounds
> unlikely) could well need an updated uClibc (or a full rebuild if it's
> crazy enough to use __SIGRTMAX).

Fixed in uclibc git: _NSIG is 128, __SIGRTMAX is 127
(_NSIG in libc is not the same as in kernel, but +1).

While at it, added extensive comment why it is so.
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