* GDB interaction with sigwait under Redhat 9.0
@ 2004-05-12 8:33 Paul Hilfinger
2004-05-12 13:55 ` Daniel Jacobowitz
0 siblings, 1 reply; 4+ messages in thread
From: Paul Hilfinger @ 2004-05-12 8:33 UTC (permalink / raw)
To: gdb
I recently submitted PR threads/1641 concerning a problem we seem to
be having with Redhat 9.0 (Linux ... 2.4.21-9.ELsmp #1 SMP Thu Jan 8
17:08:56 EST 2004 i686 i686 i386 GNU/Linux). It appears that on that
system, there is a new, malign interaction of sigwait in the inferior
with ptrace. First, GDB (head version from about mid-April), no
longer sees signals sent to an inferior that is waiting on sigwait. Second,
GDB's manipulation with the inferior causes sigwaits (at least on
pthreaded programs) to continue with a non-zero status code (EINTR to
be precise). Does anyone know anything about this rather drastic change
in sigwait's behavior? I intend to submit a GNU/Linux bug report, unless
someone knows a good reason for this new (apparently undocumented) spec.
Thanks.
Paul Hilfinger
Ada Core Technologies, Inc.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: GDB interaction with sigwait under Redhat 9.0
2004-05-12 8:33 GDB interaction with sigwait under Redhat 9.0 Paul Hilfinger
@ 2004-05-12 13:55 ` Daniel Jacobowitz
2004-05-13 9:33 ` Paul Hilfinger
0 siblings, 1 reply; 4+ messages in thread
From: Daniel Jacobowitz @ 2004-05-12 13:55 UTC (permalink / raw)
To: Paul Hilfinger; +Cc: gdb
On Wed, May 12, 2004 at 04:33:48AM -0400, Paul Hilfinger wrote:
>
> I recently submitted PR threads/1641 concerning a problem we seem to
> be having with Redhat 9.0 (Linux ... 2.4.21-9.ELsmp #1 SMP Thu Jan 8
> 17:08:56 EST 2004 i686 i686 i386 GNU/Linux). It appears that on that
> system, there is a new, malign interaction of sigwait in the inferior
> with ptrace. First, GDB (head version from about mid-April), no
> longer sees signals sent to an inferior that is waiting on sigwait. Second,
> GDB's manipulation with the inferior causes sigwaits (at least on
> pthreaded programs) to continue with a non-zero status code (EINTR to
> be precise). Does anyone know anything about this rather drastic change
> in sigwait's behavior? I intend to submit a GNU/Linux bug report, unless
> someone knows a good reason for this new (apparently undocumented) spec.
The EINTR bit is fairly typical; it is probably the C library's
obligation to hide it from you, or else the kernel's to not deliver it
in the first place, but that's a little tricky. However, you never
said what version of the Linux kernel you were using - it does not look
like 2.6 can produce this result. But then I don't see how an
unmodified 2.4 can either.
The inability to see signals received during sigwait is also a kernel
bug. Looking at the code, it replicates a portion of the path from
do_signal without duplicating the ptrace-related bits.
--
Daniel Jacobowitz
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: GDB interaction with sigwait under Redhat 9.0
2004-05-12 13:55 ` Daniel Jacobowitz
@ 2004-05-13 9:33 ` Paul Hilfinger
2004-05-13 13:30 ` Daniel Jacobowitz
0 siblings, 1 reply; 4+ messages in thread
From: Paul Hilfinger @ 2004-05-13 9:33 UTC (permalink / raw)
To: drow; +Cc: gdb
> On Wed, May 12, 2004 at 04:33:48AM -0400, Paul Hilfinger wrote:
> >
> > I recently submitted PR threads/1641 concerning a problem we seem to
> > be having with Redhat 9.0 (Linux ... 2.4.21-9.ELsmp #1 SMP Thu Jan 8
> > 17:08:56 EST 2004 i686 i686 i386 GNU/Linux). It appears that on that
> > system, there is a new, malign interaction of sigwait in the inferior
> > with ptrace. First, GDB (head version from about mid-April), no
> > longer sees signals sent to an inferior that is waiting on sigwait. Second,
> > GDB's manipulation with the inferior causes sigwaits (at least on
> > pthreaded programs) to continue with a non-zero status code (EINTR to
> > be precise). Does anyone know anything about this rather drastic change
> > in sigwait's behavior? I intend to submit a GNU/Linux bug report, unless
> > someone knows a good reason for this new (apparently undocumented) spec.
>
> However, you never
> said what version of the Linux kernel you were using - it does not look
> like 2.6 can produce this result. But then I don't see how an
> unmodified 2.4 can either.
Sorry; I thought the 2.4.21-9.ELsmp part of the uname -a line was
sufficient. In fact, not being a kernel hacker myself, I'm not sure what
information you're looking for here.
Paul Hilfinger
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: GDB interaction with sigwait under Redhat 9.0
2004-05-13 9:33 ` Paul Hilfinger
@ 2004-05-13 13:30 ` Daniel Jacobowitz
0 siblings, 0 replies; 4+ messages in thread
From: Daniel Jacobowitz @ 2004-05-13 13:30 UTC (permalink / raw)
To: Paul Hilfinger; +Cc: gdb
On Thu, May 13, 2004 at 05:33:18AM -0400, Paul Hilfinger wrote:
>
> > On Wed, May 12, 2004 at 04:33:48AM -0400, Paul Hilfinger wrote:
> > >
> > > I recently submitted PR threads/1641 concerning a problem we seem to
> > > be having with Redhat 9.0 (Linux ... 2.4.21-9.ELsmp #1 SMP Thu Jan 8
> > > 17:08:56 EST 2004 i686 i686 i386 GNU/Linux). It appears that on that
> > > system, there is a new, malign interaction of sigwait in the inferior
> > > with ptrace. First, GDB (head version from about mid-April), no
> > > longer sees signals sent to an inferior that is waiting on sigwait. Second,
> > > GDB's manipulation with the inferior causes sigwaits (at least on
> > > pthreaded programs) to continue with a non-zero status code (EINTR to
> > > be precise). Does anyone know anything about this rather drastic change
> > > in sigwait's behavior? I intend to submit a GNU/Linux bug report, unless
> > > someone knows a good reason for this new (apparently undocumented) spec.
> >
> > However, you never
> > said what version of the Linux kernel you were using - it does not look
> > like 2.6 can produce this result. But then I don't see how an
> > unmodified 2.4 can either.
>
> Sorry; I thought the 2.4.21-9.ELsmp part of the uname -a line was
> sufficient. In fact, not being a kernel hacker myself, I'm not sure what
> information you're looking for here.
Oh, it is - I just missed it. Sounds like you want to talk to your
kernel vendor.
--
Daniel Jacobowitz
^ permalink raw reply [flat|nested] 4+ messages in thread
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2004-05-12 8:33 GDB interaction with sigwait under Redhat 9.0 Paul Hilfinger
2004-05-12 13:55 ` Daniel Jacobowitz
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