qemu/util/trace-events
Jose Ricardo Ziviani 31f5a726b5 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>
2017-05-05 12:09:59 +02:00

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# See docs/tracing.txt for syntax documentation.
# util/aio-posix.c
run_poll_handlers_begin(void *ctx, int64_t max_ns) "ctx %p max_ns %"PRId64
run_poll_handlers_end(void *ctx, bool progress) "ctx %p progress %d"
poll_shrink(void *ctx, int64_t old, int64_t new) "ctx %p old %"PRId64" new %"PRId64
poll_grow(void *ctx, int64_t old, int64_t new) "ctx %p old %"PRId64" new %"PRId64
# util/async.c
aio_co_schedule(void *ctx, void *co) "ctx %p co %p"
aio_co_schedule_bh_cb(void *ctx, void *co) "ctx %p co %p"
# util/thread-pool.c
thread_pool_submit(void *pool, void *req, void *opaque) "pool %p req %p opaque %p"
thread_pool_complete(void *pool, void *req, void *opaque, int ret) "pool %p req %p opaque %p ret %d"
thread_pool_cancel(void *req, void *opaque) "req %p opaque %p"
# util/buffer.c
buffer_resize(const char *buf, size_t olen, size_t len) "%s: old %zd, new %zd"
buffer_move_empty(const char *buf, size_t len, const char *from) "%s: %zd bytes from %s"
buffer_move(const char *buf, size_t len, const char *from) "%s: %zd bytes from %s"
buffer_free(const char *buf, size_t len) "%s: capacity %zd"
# util/qemu-coroutine.c
qemu_aio_coroutine_enter(void *ctx, void *from, void *to, void *opaque) "ctx %p from %p to %p opaque %p"
qemu_coroutine_yield(void *from, void *to) "from %p to %p"
qemu_coroutine_terminate(void *co) "self %p"
# util/qemu-coroutine-lock.c
qemu_co_queue_run_restart(void *co) "co %p"
qemu_co_mutex_lock_uncontended(void *mutex, void *self) "mutex %p self %p"
qemu_co_mutex_lock_entry(void *mutex, void *self) "mutex %p self %p"
qemu_co_mutex_lock_return(void *mutex, void *self) "mutex %p self %p"
qemu_co_mutex_unlock_entry(void *mutex, void *self) "mutex %p self %p"
qemu_co_mutex_unlock_return(void *mutex, void *self) "mutex %p self %p"
# util/oslib-win32.c
# util/oslib-posix.c
qemu_memalign(size_t alignment, size_t size, void *ptr) "alignment %zu size %zu ptr %p"
qemu_anon_ram_alloc(size_t size, void *ptr) "size %zu ptr %p"
qemu_vfree(void *ptr) "ptr %p"
qemu_anon_ram_free(void *ptr, size_t size) "ptr %p size %zu"
# util/hbitmap.c
hbitmap_iter_skip_words(const void *hb, void *hbi, uint64_t pos, unsigned long cur) "hb %p hbi %p pos %"PRId64" cur 0x%lx"
hbitmap_reset(void *hb, uint64_t start, uint64_t count, uint64_t sbit, uint64_t ebit) "hb %p items %"PRIu64",%"PRIu64" bits %"PRIu64"..%"PRIu64
hbitmap_set(void *hb, uint64_t start, uint64_t count, uint64_t sbit, uint64_t ebit) "hb %p items %"PRIu64",%"PRIu64" bits %"PRIu64"..%"PRIu64
# util/lockcnt.c
lockcnt_fast_path_attempt(const void *lockcnt, int expected, int new) "lockcnt %p fast path %d->%d"
lockcnt_fast_path_success(const void *lockcnt, int expected, int new) "lockcnt %p fast path %d->%d succeeded"
lockcnt_unlock_attempt(const void *lockcnt, int expected, int new) "lockcnt %p unlock %d->%d"
lockcnt_unlock_success(const void *lockcnt, int expected, int new) "lockcnt %p unlock %d->%d succeeded"
lockcnt_futex_wait_prepare(const void *lockcnt, int expected, int new) "lockcnt %p preparing slow path %d->%d"
lockcnt_futex_wait(const void *lockcnt, int val) "lockcnt %p waiting on %d"
lockcnt_futex_wait_resume(const void *lockcnt, int new) "lockcnt %p after wait: %d"
lockcnt_futex_wake(const void *lockcnt) "lockcnt %p waking up one waiter"
# util/qemu-thread-posix.c
qemu_mutex_locked(void *lock) "locked mutex %p"
qemu_mutex_unlocked(void *lock) "unlocked mutex %p"