libs/newlib-cygwin
libs/newlib-cygwin
4
0
Fork 0
mirror of git://sourceware.org/git/newlib-cygwin.git synced 2025-02-09 02:29:07 +08:00
Code Issues Projects Releases Wiki Activity

Cygwin: signal: Fix deadlock between main thread and sig thread

Browse Source 
Previously, a deadlock happened if many SIGSTOP/SIGCONT signals were
received rapidly. If the main thread sends __SIGFLUSH at the timing
when SIGSTOP is handled by the sig thread, but not is handled by the
main thread yet (sig_handle_tty_stop() not called yet), and if SIGCONT
is received, the sig thread waits for cygtls::current_sig (is SIGSTOP
now) cleared. However, the main thread waits for the pack.wakeup using
WaitForSingleObject(), so the main thread cannot handle SIGSTOP. This
is the mechanism of the deadlock. This patch uses cygwait() instead of
WaitForSingleObject() to be able to handle the pending SIGSTOP.

Addresses: https://cygwin.com/pipermail/cygwin/2024-November/256744.html
Fixes: 7759daa979c4 ("(sig_send): Fill out sigpacket structure to send to signal thread rather than racily sending separate packets.")
Reported-by: Christian Franke <Christian.Franke@t-online.de>
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
This commit is contained in:
Takashi Yano 2024-11-25 19:51:53 +09:00
parent 522f3e921a
commit d243e51ef1
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
winsup/cygwin/sigproc.cc
View File

@ -760,7 +760,7 @@ sig_send (_pinfo *p, siginfo_t& si, _cygtls *tls)
if (wait_for_completion)
{
sigproc_printf ("Waiting for pack.wakeup %p", pack.wakeup);
rc = WaitForSingleObject (pack.wakeup, WSSC);
rc = cygwait (pack.wakeup, WSSC);
ForceCloseHandle (pack.wakeup);
}
else