On Jan 2 11:32, Takashi Yano via Cygwin wrote:
> On Thu, 29 Dec 2022 21:59:45 -0700
> Brian Inglis wrote:
> > I got some hangs (deadlock?) between (parallel?) make jobs, top, procps,
> > and
> > even ls /proc/*/ when trying to cygport all check curl or look at the
> > process
> > statuses when builds hung under Cygwin 3.4.3 and 3.5.0-0.69...
> > [...]
> I have looked into this issue a bit, and found that
> q->sigtls becomes sometimes NULL and access violation
> occurs at the following code.
>
> winsup/cygwin/sigproc.cc: 1378
> if (q->sigtls->sigmask & (bit = SIGTOMASK (q->si.si_signo)))
> {
> tl_entry = cygheap->find_tls (q->si.si_signo, issig_wait);
>
> I'm not sure why this happens, however it seems that
> the following patch fixes the issue.
>
> diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc
> index ce36c8be3..90eaa2a47 100644
> --- a/winsup/cygwin/sigproc.cc
> +++ b/winsup/cygwin/sigproc.cc
> @@ -1375,6 +1375,8 @@ wait_sig (VOID *)
> *pack.mask = 0;
> while ((q = q->next))
> {
> + if (q->sigtls == NULL)
> + continue;
> if (q->sigtls->sigmask & (bit = SIGTOMASK (q->si.si_signo)))
> {
> tl_entry = cygheap->find_tls (q->si.si_signo, issig_wait);
>
> Corinna, could you please have a look?
If q->sigtls is NULL, the signal is nevertheless waiting for being
handled. It's just not directed at a specific thread. Beats me, why
this didn't occur in my testing. The process signal info should contain
the process-wide mask of pending signals as well, obviously, so the
following patch should do the right thing:
diff --git a/winsup/cygwin/sigproc.cc b/winsup/cygwin/sigproc.cc
index ce36c8be37fb..86e4e607ab7e 100644
--- a/winsup/cygwin/sigproc.cc
+++ b/winsup/cygwin/sigproc.cc
@@ -1375,7 +1375,8 @@ wait_sig (VOID *)
*pack.mask = 0;
while ((q = q->next))
{
- if (q->sigtls->sigmask & (bit = SIGTOMASK (q->si.si_signo)))
+ _cygtls *sigtls = q->sigtls ?: _main_tls;
+ if (sigtls->sigmask & (bit = SIGTOMASK (q->si.si_signo)))
{
tl_entry = cygheap->find_tls (q->si.si_signo, issig_wait);
if (tl_entry)
Can you confirm?
Thanks,
Corinna
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