[PATCH v4 1/7] perf lock contention: Filter events before creating lock_stat

[Ian Rogers <irogers@google.com>]

In report_lock_contention_begin_event(), lock_stat_findnew() was
called before checking filters.nr_types (-Y), filters.nr_addrs (-L),
and match_callstack_filter() (-S).

When a filtered-out lock event (such as a mutex contention when
running with -Y spinlock) shared the same aggregation key as a
subsequent matching event (for example, contention on the mutex's
internal wait_lock spinlock from the same caller), the first event
created the lock_stat entry with the filtered-out lock's flags and the
second event reused that entry, causing non-spinlock entries to appear
in -Y spinlock output.

Check the type, address, and callstack filters before looking up or
creating the lock_stat entry.

Fixes: b4a7eff93c39 ("perf lock contention: Add -Y/--type-filter option")
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/builtin-lock.c | 61 +++++++++++++++++++++------------------
 1 file changed, 33 insertions(+), 28 deletions(-)

diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index d5c0d55cb82d..778923c92f42 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -975,6 +975,7 @@ static int report_lock_contention_begin_event(struct perf_sample *sample)
 	struct machine *machine = &session->machines.host;
 	struct map *kmap;
 	struct symbol *sym;
+	u64 *callstack = NULL;
 
 	ret = get_key_by_aggr_mode(&key, addr, sample);
 	if (ret < 0)
@@ -1010,33 +1011,6 @@ static int report_lock_contention_begin_event(struct perf_sample *sample)
 		}
 	}
 
-	ls = lock_stat_find(key);
-	if (!ls) {
-		char buf[128];
-		const char *name = "";
-
-		switch (aggr_mode) {
-		case LOCK_AGGR_ADDR:
-			sym = machine__find_kernel_symbol(machine, key, &kmap);
-			if (sym)
-				name = sym->name;
-			break;
-		case LOCK_AGGR_CALLER:
-			name = buf;
-			if (lock_contention_caller(sample, buf, sizeof(buf)) < 0)
-				name = "Unknown";
-			break;
-		case LOCK_AGGR_CGROUP:
-		case LOCK_AGGR_TASK:
-		default:
-			break;
-		}
-
-		ls = lock_stat_findnew(key, name, flags);
-		if (!ls)
-			return -ENOMEM;
-	}
-
 	if (filters.nr_types) {
 		bool found = false;
 
@@ -1066,7 +1040,7 @@ static int report_lock_contention_begin_event(struct perf_sample *sample)
 	}
 
 	if (needs_callstack()) {
-		u64 *callstack = get_callstack(sample, max_stack_depth);
+		callstack = get_callstack(sample, max_stack_depth);
 		if (callstack == NULL)
 			return 0;
 
@@ -1074,7 +1048,38 @@ static int report_lock_contention_begin_event(struct perf_sample *sample)
 			free(callstack);
 			return 0;
 		}
+	}
+
+	ls = lock_stat_find(key);
+	if (!ls) {
+		char buf[128];
+		const char *name = "";
+
+		switch (aggr_mode) {
+		case LOCK_AGGR_ADDR:
+			sym = machine__find_kernel_symbol(machine, key, &kmap);
+			if (sym)
+				name = sym->name;
+			break;
+		case LOCK_AGGR_CALLER:
+			name = buf;
+			if (lock_contention_caller(sample, buf, sizeof(buf)) < 0)
+				name = "Unknown";
+			break;
+		case LOCK_AGGR_CGROUP:
+		case LOCK_AGGR_TASK:
+		default:
+			break;
+		}
+
+		ls = lock_stat_findnew(key, name, flags);
+		if (!ls) {
+			free(callstack);
+			return -ENOMEM;
+		}
+	}
 
+	if (callstack) {
 		if (ls->callstack == NULL)
 			ls->callstack = callstack;
 		else
-- 
2.56.0.212.g129ede20d9-goog