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perf lock contention: Avoid variable length arrays

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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: Namhyung 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: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Namhyung Kim 2022-10-28 11:01:27 -07:00 committed by Arnaldo Carvalho de Melo
parent 0a277b6226
commit 9e9c5f3cf9
1 changed files with 28 additions and 13 deletions
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41
tools/perf/util/bpf_lock_contention.c
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@ -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)