From 7f09126e068015db54c56bb982b8f91065375700 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@who-t.net>
Date: Fri, 3 Aug 2012 15:36:34 +1000
Subject: os: don't unconditionally unblock SIGIO in OsReleaseSignals()

Calling OsReleaseSignal() inside the signal handler releases SIGIO, causing
the signal handler to be called again from within the handler.

Practical use-case: when synaptics calls TimerSet in the signal handler,
this causes the signals to be released, eventually hanging the server.

Regression introduced in 08962951de.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jeremy Huddleston <jeremyhu@apple.com>
---
 os/utils.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

(limited to 'os')

diff --git a/os/utils.c b/os/utils.c
index cdf5fd82e..947f8673a 100644
--- a/os/utils.c
+++ b/os/utils.c
@@ -1186,6 +1186,7 @@ OsBlockSignals(void)
 
 #ifdef SIG_BLOCK
 static sig_atomic_t sigio_blocked;
+static sigset_t PreviousSigIOMask;
 #endif
 
 /**
@@ -1198,13 +1199,13 @@ OsBlockSIGIO(void)
 #ifdef SIGIO
 #ifdef SIG_BLOCK
     if (sigio_blocked++ == 0) {
-        sigset_t set, old;
+        sigset_t set;
         int ret;
 
         sigemptyset(&set);
         sigaddset(&set, SIGIO);
-        sigprocmask(SIG_BLOCK, &set, &old);
-        ret = sigismember(&old, SIGIO);
+        sigprocmask(SIG_BLOCK, &set, &PreviousSigIOMask);
+        ret = sigismember(&PreviousSigIOMask, SIGIO);
         return ret;
     } else
         return 1;
@@ -1218,11 +1219,7 @@ OsReleaseSIGIO(void)
 #ifdef SIGIO
 #ifdef SIG_BLOCK
     if (--sigio_blocked == 0) {
-        sigset_t set;
-
-        sigemptyset(&set);
-        sigaddset(&set, SIGIO);
-        sigprocmask(SIG_UNBLOCK, &set, NULL);
+        sigprocmask(SIG_SETMASK, &PreviousSigIOMask, 0);
     } else if (sigio_blocked < 0) {
         BUG_WARN(sigio_blocked < 0);
         sigio_blocked = 0;
-- 
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