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Subject[PATCH v3 7/7] perf: integrate liblockdep support into perf
Date
liblockdep is simply userspace lockdep. We can use that to analyze and
verify the locking in perf.

Usage is simple, to compile perf with liblockdep all that's needed it:

make LOCKDEP=1

Once liblockdep support is compiled in, perf will yell if locking goes
wrong for any reason:

=============================================
[ INFO: possible recursive locking detected ]
liblockdep 0.0.1
---------------------------------------------
perf/23237 is trying to acquire lock:
(sched.start_work_mutex){......}, at: ./perf() [0x419793]

but task is already holding lock:
(sched.start_work_mutex){......}, at: ./perf() [0x419793]

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(sched.start_work_mutex);
lock(sched.start_work_mutex);

*** DEADLOCK ***

May be due to missing lock nesting notation

2 locks held by perf/23237:
#0: (sched.start_work_mutex){......}, at: ./perf() [0x419793]
#1: (sched.work_done_wait_mutex){......}, at: ./perf() [0x419793]

stack backtrace:
/usr/lib64/liblockdep.so(+0x1ba0)[0x7fa067f99ba0]
/usr/lib64/liblockdep.so(+0x37bf)[0x7fa067f9b7bf]
/usr/lib64/liblockdep.so(+0x3899)[0x7fa067f9b899]
/usr/lib64/liblockdep.so(+0x429a)[0x7fa067f9c29a]
/usr/lib64/liblockdep.so(+0x4db1)[0x7fa067f9cdb1]
/usr/lib64/liblockdep.so(lock_acquire+0x97)[0x7fa067f9d8b4]
./perf(cmd_sched+0xb166)[0x42d976]
./perf[0x419793]
./perf(main+0x529)[0x418f59]
/lib64/libc.so.6(__libc_start_main+0xed)[0x7fa063ae591d]
./perf[0x4190d9]

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
tools/perf/Makefile | 22 ++++++++++++++++++++++
tools/perf/builtin-sched.c | 6 ++++--
tools/perf/builtin-top.c | 4 ++++
tools/perf/config/feature-tests.mak | 12 ++++++++++++
tools/perf/perf.c | 3 +++
tools/perf/ui/setup.c | 5 ++++-
tools/perf/util/hist.h | 1 +
tools/perf/util/liblockdep.h | 11 +++++++++++
tools/perf/util/util.h | 1 +
9 files changed, 62 insertions(+), 3 deletions(-)
create mode 100644 tools/perf/util/liblockdep.h

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 8ab05e5..785cd51 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -572,6 +572,21 @@ ifneq ($(call try-cc,$(SOURCE_LIBUNWIND),$(FLAGS_UNWIND),libunwind),y)
endif # Libunwind support
endif # NO_LIBUNWIND

+ifndef NO_LIBLOCKDEP
+# for linking with liblockdep library, run like:
+# make LIBLOCKDEP=1
+ifeq ($(LOCKDEP),1)
+ LIBLOCKDEP_CFLAGS := -I../lib/lockdep/include -D__USE_LIBLOCKDEP
+ LIBLOCKDEP_LDFLAGS := -L../lib/lockdep/ -llockdep
+endif
+
+FLAGS_LIBLOCKDEP=$(LIBLOCKDEP_CFLAGS) $(ALL_CFLAGS) $(LIBLOCKDEP_LDFLAGS) $(ALL_LDFLAGS) $(EXTLIBS)
+ifneq ($(call try-cc,$(SOURCE_LIBLOCKDEP),$(FLAGS_LIBLOCKDEP),liblockdep),y)
+ msg := $(warning No liblockdep support.);
+ NO_LIBLOCKDEP := 1
+endif # liblockdep support
+endif # NO_LIBLOCKDEP
+
-include arch/$(ARCH)/Makefile

ifneq ($(OUTPUT),)
@@ -621,6 +636,13 @@ ifndef NO_LIBUNWIND
LIB_OBJS += $(OUTPUT)util/unwind.o
endif

+ifndef NO_LIBLOCKDEP
+ BASIC_CFLAGS += -D__USE_LIBLOCKDEP
+ EXTLIBS += $(LIBLOCKDEP_LIBS)
+ BASIC_CFLAGS := $(LIBLOCKDEP_CFLAGS) $(BASIC_CFLAGS)
+ BASIC_LDFLAGS := $(LIBLOCKDEP_LDFLAGS) $(BASIC_LDFLAGS)
+endif
+
ifndef NO_LIBAUDIT
FLAGS_LIBAUDIT = $(ALL_CFLAGS) $(ALL_LDFLAGS) -laudit
ifneq ($(call try-cc,$(SOURCE_LIBAUDIT),$(FLAGS_LIBAUDIT),libaudit),y)
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index cc28b85..53d9225 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -468,6 +468,8 @@ static void *thread_func(void *ctx)
char comm2[22];
int fd;

+ liblockdep_set_thread();
+
free(parms);

sprintf(comm2, ":%s", this_task->comm);
@@ -1677,8 +1679,8 @@ int cmd_sched(int argc, const char **argv, const char *prefix __maybe_unused)
},
.cmp_pid = LIST_HEAD_INIT(sched.cmp_pid),
.sort_list = LIST_HEAD_INIT(sched.sort_list),
- .start_work_mutex = PTHREAD_MUTEX_INITIALIZER,
- .work_done_wait_mutex = PTHREAD_MUTEX_INITIALIZER,
+ .start_work_mutex = LIBLOCKDEP_PTHREAD_MUTEX_INITIALIZER(sched.start_work_mutex),
+ .work_done_wait_mutex = LIBLOCKDEP_PTHREAD_MUTEX_INITIALIZER(sched.work_done_wait_mutex),
.curr_pid = { [0 ... MAX_CPUS - 1] = -1 },
.sort_order = default_sort_order,
.replay_repeat = 10,
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index c9ff395..c9b99ef 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -588,6 +588,8 @@ static void *display_thread_tui(void *arg)
.refresh = top->delay_secs,
};

+ liblockdep_set_thread();
+
perf_top__sort_new_samples(top);

/*
@@ -613,6 +615,8 @@ static void *display_thread(void *arg)
struct perf_top *top = arg;
int delay_msecs, c;

+ liblockdep_set_thread();
+
tcgetattr(0, &save);
tc = save;
tc.c_lflag &= ~(ICANON | ECHO);
diff --git a/tools/perf/config/feature-tests.mak b/tools/perf/config/feature-tests.mak
index f5ac774..1f5a37e 100644
--- a/tools/perf/config/feature-tests.mak
+++ b/tools/perf/config/feature-tests.mak
@@ -217,6 +217,18 @@ int main(void)
endef
endif

+ifndef NO_LIBLOCKDEP
+define SOURCE_LIBLOCKDEP
+#include <liblockdep/mutex.h>
+
+int main(void)
+{
+ liblockdep_init();
+ return 0;
+}
+endef
+endif
+
define SOURCE_ON_EXIT
#include <stdio.h>

diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 0f661fb..ddbd315 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -446,6 +446,9 @@ int main(int argc, const char **argv)
{
const char *cmd;

+ liblockdep_init();
+ liblockdep_set_thread();
+
page_size = sysconf(_SC_PAGE_SIZE);

cmd = perf_extract_argv0_path(argv[0]);
diff --git a/tools/perf/ui/setup.c b/tools/perf/ui/setup.c
index ebb4cc1..5c0cdeb 100644
--- a/tools/perf/ui/setup.c
+++ b/tools/perf/ui/setup.c
@@ -3,14 +3,17 @@
#include "../util/cache.h"
#include "../util/debug.h"
#include "../util/hist.h"
+#include "../util/liblockdep.h"

-pthread_mutex_t ui__lock = PTHREAD_MUTEX_INITIALIZER;
+pthread_mutex_t ui__lock;

void setup_browser(bool fallback_to_pager)
{
if (!isatty(1) || dump_trace)
use_browser = 0;

+ pthread_mutex_init(&ui__lock, NULL);
+
/* default to TUI */
if (use_browser < 0)
use_browser = 1;
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index 8b091a5..328afe0 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -5,6 +5,7 @@
#include <pthread.h>
#include "callchain.h"
#include "header.h"
+#include "liblockdep.h"

extern struct callchain_param callchain_param;

diff --git a/tools/perf/util/liblockdep.h b/tools/perf/util/liblockdep.h
new file mode 100644
index 0000000..628a2f5
--- /dev/null
+++ b/tools/perf/util/liblockdep.h
@@ -0,0 +1,11 @@
+#ifdef __USE_LIBLOCKDEP
+
+#include <liblockdep/mutex.h>
+
+#else
+
+#define LIBLOCKDEP_PTHREAD_MUTEX_INITIALIZER(mtx) PTHREAD_MUTEX_INITIALIZER
+#define liblockdep_init()
+#define liblockdep_set_thread()
+
+#endif
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index c233091..06e6244 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -73,6 +73,7 @@
#include <linux/magic.h>
#include "types.h"
#include <sys/ttydefaults.h>
+#include "liblockdep.h"

extern const char *graph_line;
extern const char *graph_dotted_line;
--
1.8.1.2


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