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>
This commit is contained in:
Paolo Bonzini 2018-06-13 14:23:08 +02:00
parent f1aff7aa8e
commit ba59fb778e
4 changed files with 30 additions and 0 deletions

10
configure vendored
View file

@ -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

View file

@ -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;
};

View file

@ -5,6 +5,10 @@
struct QemuMutex {
SRWLOCK lock;
#ifdef CONFIG_DEBUG_MUTEX
const char *file;
int line;
#endif
bool initialized;
};

View file

@ -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);
}