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Re: [Qemu-devel] Hang in aio/multi/mutex/mcs
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] Hang in aio/multi/mutex/mcs |
Date: |
Fri, 24 Feb 2017 17:22:36 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 |
On 23/02/2017 20:48, Alex Bennée wrote:
> Hope that helps the debugging ;-)
Worst case we can just remove the test (it's only there for performance
comparison, not a bug in actual QEMU code), but this seems to help here:
diff --git a/tests/test-aio-multithread.c b/tests/test-aio-multithread.c
index f11e990..8b0b40e 100644
--- a/tests/test-aio-multithread.c
+++ b/tests/test-aio-multithread.c
@@ -309,7 +309,7 @@ static void mcs_mutex_lock(void)
static void mcs_mutex_unlock(void)
{
int next;
- if (nodes[id].next == -1) {
+ if (atomic_read(&nodes[id].next) == -1) {
if (atomic_read(&mutex_head) == id &&
atomic_cmpxchg(&mutex_head, id, -1) == id) {
/* Last item in the list, exit. */
@@ -323,7 +323,7 @@ static void mcs_mutex_unlock(void)
}
/* Wake up the next in line. */
- next = nodes[id].next;
+ next = atomic_read(&nodes[id].next);
nodes[next].locked = 0;
qemu_futex_wake(&nodes[next].locked, 1);
}
Paolo