| Message ID | 20180423053927.13715-4-peterx@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v4,1/4] tests/atomic_add-bench: add -m option to use mutexes | expand |
On Mon, Apr 23, 2018 at 13:39:26 +0800, Peter Xu wrote: > We have had some tracing tools for mutex but it's not easy to use them > for e.g. dead locks. Let's provide "--enable-debug-mutex" parameter > when configure to allow QemuMutex to store the last owner that took > specific lock. It will be easy to use this tool to debug deadlocks > since we can directly know who took the lock then as long as we can have > a debugger attached to the process. > > Signed-off-by: Peter Xu <peterx@redhat.com> > --- (snip) > static inline void qemu_mutex_pre_unlock(QemuMutex *mutex, > const char *file, int line) > { > +#ifdef CONFIG_DEBUG_MUTEX > + mutex->file = NULL; > + mutex->line = 0; > +#endif > trace_qemu_mutex_unlock(mutex, file, line); > } I'd also initialize to NULL/0 the file/line pair at qemu_mutex_init time for both posix and win32. Other than that: Reviewed-by: Emilio G. Cota <cota@braap.org> Thanks, E.
On Mon, Apr 23, 2018 at 02:11:07PM -0400, Emilio G. Cota wrote: > On Mon, Apr 23, 2018 at 13:39:26 +0800, Peter Xu wrote: > > We have had some tracing tools for mutex but it's not easy to use them > > for e.g. dead locks. Let's provide "--enable-debug-mutex" parameter > > when configure to allow QemuMutex to store the last owner that took > > specific lock. It will be easy to use this tool to debug deadlocks > > since we can directly know who took the lock then as long as we can have > > a debugger attached to the process. > > > > Signed-off-by: Peter Xu <peterx@redhat.com> > > --- > (snip) > > static inline void qemu_mutex_pre_unlock(QemuMutex *mutex, > > const char *file, int line) > > { > > +#ifdef CONFIG_DEBUG_MUTEX > > + mutex->file = NULL; > > + mutex->line = 0; > > +#endif > > trace_qemu_mutex_unlock(mutex, file, line); > > } > > I'd also initialize to NULL/0 the file/line pair at > qemu_mutex_init time for both posix and win32. Other than that: > > Reviewed-by: Emilio G. Cota <cota@braap.org> I did the same trick for mutex init in patch 2 & 3 and reposted, while I picked up your r-b for patch 4 only. Please have a look. Thanks,
diff --git a/configure b/configure index 0a19b033bc..a80af735b2 100755 --- a/configure +++ b/configure @@ -451,6 +451,7 @@ jemalloc="no" replication="yes" vxhs="" libxml2="" +debug_mutex="no" supported_cpu="no" supported_os="no" @@ -1374,6 +1375,10 @@ for opt do ;; --disable-git-update) git_update=no ;; + --enable-debug-mutex) debug_mutex=yes + ;; + --disable-debug-mutex) debug_mutex=no + ;; *) echo "ERROR: unknown option $opt" echo "Try '$0 --help' for more information" @@ -1631,6 +1636,7 @@ disabled with --disable-FEATURE, default is enabled if available: crypto-afalg Linux AF_ALG crypto backend driver vhost-user vhost-user support capstone capstone disassembler support + debug-mutex mutex debugging support NOTE: The object files are built at the place where configure is launched EOF @@ -5874,6 +5880,7 @@ echo "avx2 optimization $avx2_opt" echo "replication support $replication" echo "VxHS block device $vxhs" echo "capstone $capstone" +echo "mutex debugging $debug_mutex" if test "$sdl_too_old" = "yes"; then echo "-> Your SDL version is too old - please upgrade to have SDL support" @@ -6602,6 +6609,9 @@ fi if test "$capstone" != "no" ; then echo "CONFIG_CAPSTONE=y" >> $config_host_mak fi +if test "$debug_mutex" = "yes" ; then + echo "CONFIG_DEBUG_MUTEX=y" >> $config_host_mak +fi # Hold two types of flag: # CONFIG_THREAD_SETNAME_BYTHREAD - we've got a way of setting the name on diff --git a/include/qemu/thread-posix.h b/include/qemu/thread-posix.h index f3f47e426f..fd27b34128 100644 --- a/include/qemu/thread-posix.h +++ b/include/qemu/thread-posix.h @@ -12,6 +12,10 @@ typedef QemuMutex QemuRecMutex; struct QemuMutex { pthread_mutex_t lock; +#ifdef CONFIG_DEBUG_MUTEX + const char *file; + int line; +#endif bool initialized; }; diff --git a/include/qemu/thread-win32.h b/include/qemu/thread-win32.h index 3a05e3b3aa..d668d789b4 100644 --- a/include/qemu/thread-win32.h +++ b/include/qemu/thread-win32.h @@ -5,6 +5,10 @@ struct QemuMutex { SRWLOCK lock; +#ifdef CONFIG_DEBUG_MUTEX + const char *file; + int line; +#endif bool initialized; }; diff --git a/util/qemu-thread-common.h b/util/qemu-thread-common.h index 324915fb80..90845842f2 100644 --- a/util/qemu-thread-common.h +++ b/util/qemu-thread-common.h @@ -26,12 +26,20 @@ static inline void qemu_mutex_pre_lock(QemuMutex *mutex, static inline void qemu_mutex_post_lock(QemuMutex *mutex, const char *file, int line) { +#ifdef CONFIG_DEBUG_MUTEX + mutex->file = file; + mutex->line = line; +#endif trace_qemu_mutex_locked(mutex, file, line); } static inline void qemu_mutex_pre_unlock(QemuMutex *mutex, const char *file, int line) { +#ifdef CONFIG_DEBUG_MUTEX + mutex->file = NULL; + mutex->line = 0; +#endif trace_qemu_mutex_unlock(mutex, file, line); }
We have had some tracing tools for mutex but it's not easy to use them for e.g. dead locks. Let's provide "--enable-debug-mutex" parameter when configure to allow QemuMutex to store the last owner that took specific lock. It will be easy to use this tool to debug deadlocks since we can directly know who took the lock then as long as we can have a debugger attached to the process. Signed-off-by: Peter Xu <peterx@redhat.com> --- configure | 10 ++++++++++ include/qemu/thread-posix.h | 4 ++++ include/qemu/thread-win32.h | 4 ++++ util/qemu-thread-common.h | 8 ++++++++ 4 files changed, 26 insertions(+)