commit 2ae42c4edb8d14fa5cabf46f041ffef1090e8d0c
author Ben Fennema <fennema@google.com> Wed Sep 21 14:38:50 2016 -0700
committer Ben Fennema <fennema@google.com> Wed Sep 21 14:56:21 2016 -0700
tree 80669b4e456cdd5ce678cab20f22f7f2045147ff
parent 93abd206644e40146daaa873fdd2f297b9322f8b

exti: return error when double adding or removing chained isrs

Calling extiChainIsr twice with no extiUnchainIsr in between would
corrupt the shared isr list.

Bug: 31653505
Change-Id: I3c4b852e6d815545ccf49602b8770d162a791d60
Signed-off-by: Ben Fennema <fennema@google.com>

firmware/src/platform/stm32f4xx/exti.c

diff --git a/firmware/src/platform/stm32f4xx/exti.c b/firmware/src/platform/stm32f4xx/exti.c
index 2543ac2..5d5cb4b 100644
--- a/firmware/src/platform/stm32f4xx/exti.c
+++ b/firmware/src/platform/stm32f4xx/exti.c
@@ -186,6 +186,8 @@
     struct ExtiInterrupt *exti = extiForIrq(n);
     if (!exti)
         return -EINVAL;
+    else if (!list_is_empty(&isr->node))
+        return -EINVAL;
 
     chainIsr(&exti->base, isr);
     if (!mMaxLatency || (isr->maxLatencyNs && isr->maxLatencyNs < mMaxLatency))
@@ -199,6 +201,8 @@
     struct ExtiInterrupt *exti = extiForIrq(n);
     if (!exti)
         return -EINVAL;
+    else if (list_is_empty(&isr->node))
+        return -EINVAL;
 
     unchainIsr(&exti->base, isr);
     if (isr->maxLatencyNs && isr->maxLatencyNs == mMaxLatency)