commit 10962fbfa7d21373d774840bd71c8a21ac96cd56
author Alexey Polyudov <apolyudov@google.com> Tue Mar 15 11:51:25 2016 -0700
committer Alexey Polyudov <apolyudov@google.com> Wed Mar 16 13:06:38 2016 -0700
tree a700de764a892feb9c0136e23bee08cbb9dd0d1c
parent 6f7191dd8a3c760a8aa76841019f07c755db7611

timer: fix race condition in timFireAsNeededAndUpdateAlarms

timFireAsNeededAndUpdateAlarms() may be called from
timer interrupt and from timTimerSetEx()

if interrupted, and reentered it may incorrectly update
internal state, and produce unwanted side effects,
e.g. invoke the same timer handler multiple times.

interrupts disabled inside timFireAsNeededAndUpdateAlarms()
to prevent that from happening

Change-Id: I6484925cbe91f9deb5d33eb50e34b32254dda607
Signed-off-by: Alexey Polyudov <apolyudov@google.com>

firmware/src/timer.c

diff --git a/firmware/src/timer.c b/firmware/src/timer.c
index 313d8d8..3a9d49f 100644
--- a/firmware/src/timer.c
+++ b/firmware/src/timer.c
@@ -94,6 +94,9 @@
     uint32_t i, id;
     void *callData;
 
+    // protect from concurrent execution [timIntHandler() and timTimerSetEx()]
+    uint64_t intSta = cpuIntsOff();
+
     do {
         somethingDone = false;
         nextTimer = 0;
@@ -135,6 +138,8 @@
     if (!nextTimer)
         platSleepClockRequest(0, 0, 0, 0);
 
+    cpuIntsRestore(intSta);
+
     return totalSomethingDone;
 }