[libvirt] [PATCH] virThreadPoolFree: Set n(Prio)Workers after the pool is locked
In 78839da I am trying to join the worker threads. However, I can't
sipmly reuse pool->nWorkers (same applies for pool->nPrioWorkers),
because of the following flow that is currently implemented:
1) the main thread executing virThreadPoolFree sets pool->quit = true,
wakes up all the workers and wait on pool->quit_cond.
2) A worker is woken up and see quit request. It immediately jumps of
the while() loop and decrements pool->nWorkers (or pool->nPrioWorkers in
case of priority worker). The last thread signalizes pool->quit_cond.
3) Main thread is woken up, with both pool->nWorkers and
pool->nPrioWorkers being zero.
So there's a need to copy the original value of worker thread counts
into local variables. However, these need to set *after* the check for
pool being NULL (dereferencing a NULL is no no). And for safety they can
be set right after the pool is locked.
Reported-by: John Ferlan <jferlan(a)redhat.com>
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/util/virthreadpool.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/src/util/virthreadpool.c b/src/util/virthreadpool.c
index 99f36ec..aa442d1 100644
--- a/src/util/virthreadpool.c
+++ b/src/util/virthreadpool.c
@@ -242,13 +242,15 @@ void virThreadPoolFree(virThreadPoolPtr pool)
virThreadPoolJobPtr job;
bool priority = false;
size_t i;
- size_t nWorkers = pool->nWorkers;
- size_t nPrioWorkers = pool->nPrioWorkers;
+ size_t nWorkers;
+ size_t nPrioWorkers;
if (!pool)
return;
virMutexLock(&pool->mutex);
+ nWorkers = pool->nWorkers;
+ nPrioWorkers = pool->nPrioWorkers;
pool->quit = true;
if (pool->nWorkers > 0)
virCondBroadcast(&pool->cond);
--
1.8.4.4