commit 89b9ba661bd2d6155308f895ec075d813f0e129b
author Alexandre Raymond <cerbere@gmail.com> Wed Jun 15 01:20:31 2011 -0400
committer Blue Swirl <blauwirbel@gmail.com> Sat Jul 16 19:43:00 2011 +0000
tree f7ea26ffe7cea8eb7acea9566b7871f7d8a384cb
parent 5664aed99a4ab6e661b40e475449a32150f46184

Fix signal handling of SIG_IPI when io-thread is enabled

Both the signal thread (via sigwait()) and the cpu thread (via
a normal signal handler) were attempting to catch SIG_IPI.

This resulted in random freezes under Darwin.

This patch separates SIG_IPI from the rest of the signals handled
by the signal thread, because it is independently caught by the cpu
thread.

Signed-off-by: Alexandre Raymond <cerbere@gmail.com>
Acked-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

cpus.c

diff --git a/cpus.c b/cpus.c
index e02576c..3035314 100644
--- a/cpus.c
+++ b/cpus.c
@@ -396,10 +396,18 @@
     sigaddset(&set, SIGUSR2);
     pthread_sigmask(SIG_UNBLOCK, &set, NULL);
 
+    /*
+     * SIG_IPI must be blocked in the main thread and must not be caught
+     * by sigwait() in the signal thread. Otherwise, the cpu thread will
+     * not catch it reliably.
+     */
+    sigemptyset(&set);
+    sigaddset(&set, SIG_IPI);
+    pthread_sigmask(SIG_BLOCK, &set, NULL);
+
     sigemptyset(&set);
     sigaddset(&set, SIGIO);
     sigaddset(&set, SIGALRM);
-    sigaddset(&set, SIG_IPI);
     sigaddset(&set, SIGBUS);
 #else
     sigemptyset(&set);