Commit 9e9c5f3c authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

perf lock contention: Avoid variable length arrays 



The msan also warns about the use of VLA for stack_trace variable.
We can dynamically allocate instead.  While at it, simplify the error
handle a bit (and fix bugs).

Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221028180128.3311491-4-namhyung@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 0a277b62

tools/perf/util/bpf_lock_contention.c

+28 −13
Original line number Diff line number Diff line
@@ -108,28 +108,36 @@ int lock_contention_stop(void) 


int lock_contention_read(struct lock_contention *con)

{

	int fd, stack;

	int fd, stack, err = 0;

	s32 prev_key, key;

	struct lock_contention_data data = {};

	struct lock_stat *st;

	struct lock_stat *st = NULL;

	struct machine *machine = con->machine;

	u64 stack_trace[con->max_stack];

	u64 *stack_trace;

	size_t stack_size = con->max_stack * sizeof(*stack_trace);



	fd = bpf_map__fd(skel->maps.lock_stat);

	stack = bpf_map__fd(skel->maps.stacks);



	con->lost = skel->bss->lost;



	stack_trace = zalloc(stack_size);

	if (stack_trace == NULL)

		return -1;



	prev_key = 0;

	while (!bpf_map_get_next_key(fd, &prev_key, &key)) {

		struct map *kmap;

		struct symbol *sym;

		int idx = 0;



		/* to handle errors in the loop body */

		err = -1;



		bpf_map_lookup_elem(fd, &key, &data);

		st = zalloc(sizeof(*st));

		if (st == NULL)

			return -1;

			break;



		st->nr_contended = data.count;

		st->wait_time_total = data.total_time;
@@ -163,25 +171,32 @@ int lock_contention_read(struct lock_contention *con) 
				st->name = strdup(sym->name);



			if (ret < 0 || st->name == NULL)

				return -1;

				break;

		} else if (asprintf(&st->name, "%#lx", (unsigned long)st->addr) < 0) {

			free(st);

			return -1;

			break;

		}



		if (verbose) {

			st->callstack = memdup(stack_trace, sizeof(stack_trace));

			if (st->callstack == NULL) {

				free(st);

				return -1;

			}

			st->callstack = memdup(stack_trace, stack_size);

			if (st->callstack == NULL)

				break;

		}



		hlist_add_head(&st->hash_entry, con->result);

		prev_key = key;



		/* we're fine now, reset the values */

		st = NULL;

		err = 0;

	}



	return 0;

	free(stack_trace);

	if (st) {

		free(st->name);

		free(st);

	}



	return err;

}



int lock_contention_finish(void)