perf lock contention: Prepare to handle cgroups

Save cgroup info and display cgroup names if requested.  This is a
preparation for the next patch.
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230906174903.346486-3-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-lock.c

@@ -2040,6 +2040,7 @@ static int __cmd_contention(int argc, const char **argv)
 		.filters = &filters,
 		.save_callstack = needs_callstack(),
 		.owner = show_lock_owner,
+		.cgroups = RB_ROOT,
 	};
 
 	lockhash_table = calloc(LOCKHASH_SIZE, sizeof(*lockhash_table));
@@ -2158,7 +2159,7 @@ static int __cmd_contention(int argc, const char **argv)
 out_delete:
 	lock_filter_finish();
 	evlist__delete(con.evlist);
-	lock_contention_finish();
+	lock_contention_finish(&con);
 	perf_session__delete(session);
 	zfree(&lockhash_table);
 	return err;

tools/perf/util/bpf_lock_contention.c

 // SPDX-License-Identifier: GPL-2.0
+#include "util/cgroup.h"
 #include "util/debug.h"
 #include "util/evlist.h"
 #include "util/machine.h"
@@ -151,6 +152,10 @@ int lock_contention_prepare(struct lock_contention *con)
 	skel->bss->needs_callstack = con->save_callstack;
 	skel->bss->lock_owner = con->owner;
 
+	if (con->use_cgroup) {
+		read_all_cgroups(&con->cgroups);
+	}
+
 	bpf_program__set_autoload(skel->progs.collect_lock_syms, false);
 
 	lock_contention_bpf__attach(skel);
@@ -222,6 +227,17 @@ static const char *lock_contention_get_name(struct lock_contention *con,
 		return "";
 	}
 
+	if (con->use_cgroup) {
+		u64 cgrp_id = key->lock_addr;
+		struct cgroup *cgrp = __cgroup__find(&con->cgroups, cgrp_id);
+
+		if (cgrp)
+			return cgrp->name;
+
+		snprintf(name_buf, sizeof(name_buf), "cgroup:%lu", cgrp_id);
+		return name_buf;
+	}
+
 	/* LOCK_AGGR_CALLER: skip lock internal functions */
 	while (machine__is_lock_function(machine, stack_trace[idx]) &&
 	       idx < con->max_stack - 1)
@@ -364,12 +380,20 @@ int lock_contention_read(struct lock_contention *con)
 	return err;
 }
 
-int lock_contention_finish(void)
+int lock_contention_finish(struct lock_contention *con)
 {
 	if (skel) {
 		skel->bss->enabled = 0;
 		lock_contention_bpf__destroy(skel);
 	}
 
+	while (!RB_EMPTY_ROOT(&con->cgroups)) {
+		struct rb_node *node = rb_first(&con->cgroups);
+		struct cgroup *cgrp = rb_entry(node, struct cgroup, node);
+
+		rb_erase(node, &con->cgroups);
+		cgroup__put(cgrp);
+	}
+
 	return 0;
 }

tools/perf/util/lock-contention.h

@@ -136,6 +136,7 @@ struct lock_contention {
 	struct hlist_head *result;
 	struct lock_filter *filters;
 	struct lock_contention_fails fails;
+	struct rb_root cgroups;
 	unsigned long map_nr_entries;
 	int max_stack;
 	int stack_skip;
@@ -143,6 +144,7 @@ struct lock_contention {
 	int owner;
 	int nr_filtered;
 	bool save_callstack;
+	bool use_cgroup;
 };
 
 #ifdef HAVE_BPF_SKEL
@@ -151,7 +153,7 @@ int lock_contention_prepare(struct lock_contention *con);
 int lock_contention_start(void);
 int lock_contention_stop(void);
 int lock_contention_read(struct lock_contention *con);
-int lock_contention_finish(void);
+int lock_contention_finish(struct lock_contention *con);
 
 #else  /* !HAVE_BPF_SKEL */
 
@@ -162,7 +164,10 @@ static inline int lock_contention_prepare(struct lock_contention *con __maybe_un
 
 static inline int lock_contention_start(void) { return 0; }
 static inline int lock_contention_stop(void) { return 0; }
-static inline int lock_contention_finish(void) { return 0; }
+static inline int lock_contention_finish(struct lock_contention *con __maybe_unused)
+{
+	return 0;
+}
 
 static inline int lock_contention_read(struct lock_contention *con __maybe_unused)
 {