From ba59fb778ec68b072196cff9af11c7612a6e52f2 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 13 Jun 2018 14:23:08 +0200 Subject: [PATCH] QemuMutex: support --enable-debug-mutex 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. Reviewed-by: Emilio G. Cota Signed-off-by: Peter Xu Message-Id: <20180425025459.5258-4-peterx@redhat.com> Signed-off-by: Paolo Bonzini --- configure | 10 ++++++++++ include/qemu/thread-posix.h | 4 ++++ include/qemu/thread-win32.h | 4 ++++ util/qemu-thread-common.h | 12 ++++++++++++ 4 files changed, 30 insertions(+) diff --git a/configure b/configure index 4d12cfbe3f..3f53aa76fd 100755 --- a/configure +++ b/configure @@ -456,6 +456,7 @@ replication="yes" vxhs="" libxml2="" docker="no" +debug_mutex="no" # cross compilers defaults, can be overridden with --cross-cc-ARCH cross_cc_aarch64="aarch64-linux-gnu-gcc" @@ -1411,6 +1412,10 @@ 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" @@ -1685,6 +1690,7 @@ 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 @@ -5951,6 +5957,7 @@ echo "seccomp support $seccomp" echo "coroutine backend $coroutine" echo "coroutine pool $coroutine_pool" echo "debug stack usage $debug_stack_usage" +echo "mutex debugging $debug_mutex" echo "crypto afalg $crypto_afalg" echo "GlusterFS support $glusterfs" echo "gcov $gcov_tool" @@ -6704,6 +6711,9 @@ fi if test "$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 d3292084d6..a0ea7c0d92 100644 --- a/util/qemu-thread-common.h +++ b/util/qemu-thread-common.h @@ -19,6 +19,10 @@ static inline void qemu_mutex_post_init(QemuMutex *mutex) { +#ifdef CONFIG_DEBUG_MUTEX + mutex->file = NULL; + mutex->line = 0; +#endif mutex->initialized = true; } @@ -31,12 +35,20 @@ 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); }