From 0e438cdc932a785de72166af4641aafa103a6670 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Thu, 11 Aug 2016 17:45:06 +0200 Subject: [PATCH] coroutine: Let CoMutex remember who holds it In cases of deadlocks, knowing who holds a given CoMutex is really helpful for debugging. Keeping the information around doesn't cost much and allows us to add another assertion to keep the code correct, so let's just add it. Signed-off-by: Kevin Wolf Reviewed-by: Paolo Bonzini Reviewed-by: Stefan Hajnoczi --- include/qemu/coroutine.h | 1 + util/qemu-coroutine-lock.c | 3 +++ 2 files changed, 4 insertions(+) diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h index ac8d4c9cc8..29a20782f0 100644 --- a/include/qemu/coroutine.h +++ b/include/qemu/coroutine.h @@ -143,6 +143,7 @@ bool qemu_co_queue_empty(CoQueue *queue); */ typedef struct CoMutex { bool locked; + Coroutine *holder; CoQueue queue; } CoMutex; diff --git a/util/qemu-coroutine-lock.c b/util/qemu-coroutine-lock.c index 22aa9abb30..f30ee8184d 100644 --- a/util/qemu-coroutine-lock.c +++ b/util/qemu-coroutine-lock.c @@ -129,6 +129,7 @@ void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex) } mutex->locked = true; + mutex->holder = self; trace_qemu_co_mutex_lock_return(mutex, self); } @@ -140,9 +141,11 @@ void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex) trace_qemu_co_mutex_unlock_entry(mutex, self); assert(mutex->locked == true); + assert(mutex->holder == self); assert(qemu_in_coroutine()); mutex->locked = false; + mutex->holder = NULL; qemu_co_queue_next(&mutex->queue); trace_qemu_co_mutex_unlock_return(mutex, self); -- 2.11.4.GIT