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authorPaolo Bonzini <pbonzini@redhat.com>2018-06-13 14:23:08 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2018-06-28 19:05:32 +0200
commitba59fb778ec68b072196cff9af11c7612a6e52f2 (patch)
treeed0008190d1ecec2102d9f506a879f2e119a930b
parentf1aff7aa8e6f238909bd0b0e7a1fe235802843f2 (diff)
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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 <cota@braap.org> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20180425025459.5258-4-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rwxr-xr-xconfigure10
-rw-r--r--include/qemu/thread-posix.h4
-rw-r--r--include/qemu/thread-win32.h4
-rw-r--r--util/qemu-thread-common.h12
4 files changed, 30 insertions, 0 deletions
diff --git a/configure b/configure
index 4d12cfb..3f53aa7 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 f3f47e4..fd27b34 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 3a05e3b..d668d78 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 d329208..a0ea7c0 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);
}