diff options
author | Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com> | 2017-04-24 14:19:58 -0300 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-05-05 12:09:59 +0200 |
commit | 31f5a726b59bda5580e2f9413867893501dd7d93 (patch) | |
tree | 33c91bb25066d13fc9f79aae3ca2379465dcbe51 /util/qemu-thread-win32.c | |
parent | f68826989cd4d1217797251339579c57b3c0934e (diff) |
trace: add qemu mutex lock and unlock trace events
These trace events were very useful to help me to understand and find a
reordering issue in vfio, for example:
qemu_mutex_lock locked mutex 0x10905ad8
vfio_region_write (0001:03:00.0:region1+0xc0, 0x2020c, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
qemu_mutex_lock locked mutex 0x10905ad8
vfio_region_write (0001:03:00.0:region1+0xc4, 0xa0000, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
that also helped me to see the desired result after the fix:
qemu_mutex_lock locked mutex 0x10905ad8
vfio_region_write (0001:03:00.0:region1+0xc0, 0x2000c, 4)
vfio_region_write (0001:03:00.0:region1+0xc4, 0xb0000, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
So it could be a good idea to have these traces implemented. It's worth
mentioning that they should be surgically enabled during the debugging,
otherwise it can flood the trace logs with lock/unlock messages.
How to use it:
trace-event qemu_mutex_lock on|off
trace-event qemu_mutex_unlock on|off
or
trace-event qemu_mutex* on|off
Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
Message-Id: <1493054398-26013-1-git-send-email-joserz@linux.vnet.ibm.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
[Also handle trylock, cond_wait and win32; trace "unlocked" while still
in the critical section, so that "unlocked" always comes before the
next "locked" tracepoint. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'util/qemu-thread-win32.c')
-rw-r--r-- | util/qemu-thread-win32.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c index 59befd5202..653f29f442 100644 --- a/util/qemu-thread-win32.c +++ b/util/qemu-thread-win32.c @@ -19,6 +19,7 @@ #include "qemu-common.h" #include "qemu/thread.h" #include "qemu/notify.h" +#include "trace.h" #include <process.h> static bool name_threads; @@ -55,6 +56,7 @@ void qemu_mutex_destroy(QemuMutex *mutex) void qemu_mutex_lock(QemuMutex *mutex) { AcquireSRWLockExclusive(&mutex->lock); + trace_qemu_mutex_locked(mutex); } int qemu_mutex_trylock(QemuMutex *mutex) @@ -62,11 +64,16 @@ int qemu_mutex_trylock(QemuMutex *mutex) int owned; owned = TryAcquireSRWLockExclusive(&mutex->lock); - return !owned; + if (owned) { + trace_qemu_mutex_locked(mutex); + return 0; + } + return -EBUSY; } void qemu_mutex_unlock(QemuMutex *mutex) { + trace_qemu_mutex_unlocked(mutex); ReleaseSRWLockExclusive(&mutex->lock); } @@ -118,7 +125,9 @@ void qemu_cond_broadcast(QemuCond *cond) void qemu_cond_wait(QemuCond *cond, QemuMutex *mutex) { + trace_qemu_mutex_unlocked(mutex); SleepConditionVariableSRW(&cond->var, &mutex->lock, INFINITE, 0); + trace_qemu_mutex_locked(mutex); } void qemu_sem_init(QemuSemaphore *sem, int init) |