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perf kvm: Reference count 'struct kvm_info'

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hists__add_entry_ops() doesn't allocate a new histogram entry if it has
an existing entry for a KVM event, in this case, find_create_kvm_event()
allocates a 'struct kvm_info' but it's not used by any histograms and
never freed.

To fix the memory leak, this patch first introduces a refcnt and a set
of functions for refcnt operations on 'struct kvm_info'.  When the data
structure is not anymore used (the refcnt hits zero) kvm_info__zput()
will free the memory used.

Committer:

Provide a nop version of kvm_info__zput() to be used when
HAVE_KVM_STAT_SUPPORT isn't defined as it is used unconditionally in
hists__findnew_entry() and hist_entry__delete().

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230320061619.29520-2-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Leo Yan 2023-03-20 14:16:18 +08:00 committed by Arnaldo Carvalho de Melo
parent ea15483e7c
commit f1e8f25980
3 changed files with 46 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
tools/perf/builtin-kvm.c
View File

@ -768,7 +768,6 @@ static void kvm_he_free(void *he)
{
struct kvm_event *kvm_ev;
free(((struct hist_entry *)he)->kvm_info);
kvm_ev = container_of(he, struct kvm_event, he);
free(kvm_ev);
}
@ -788,7 +787,7 @@ static struct kvm_event *find_create_kvm_event(struct perf_kvm_stat *kvm,
BUG_ON(key->key == INVALID_KEY);
ki = zalloc(sizeof(*ki));
ki = kvm_info__new();
if (!ki) {
pr_err("Failed to allocate kvm info\n");
return NULL;

5
tools/perf/util/hist.c
View File

@ -628,6 +628,8 @@ static struct hist_entry *hists__findnew_entry(struct hists *hists,
block_info__zput(entry->block_info);
kvm_info__zput(entry->kvm_info);
/* If the map of an existing hist_entry has
* become out-of-date due to an exec() or
* similar, update it. Otherwise we will
@ -1324,6 +1326,9 @@ void hist_entry__delete(struct hist_entry *he)
if (he->block_info)
block_info__zput(he->block_info);
if (he->kvm_info)
kvm_info__zput(he->kvm_info);
zfree(&he->res_samples);
zfree(&he->stat_acc);
free_srcline(he->srcline);

40
tools/perf/util/kvm-stat.h
View File

@ -10,6 +10,9 @@
#include "symbol.h"
#include "record.h"
#include <stdlib.h>
#include <linux/zalloc.h>
#define KVM_EVENT_NAME_LEN 40
struct evsel;
@ -25,6 +28,7 @@ struct event_key {
struct kvm_info {
char name[KVM_EVENT_NAME_LEN];
refcount_t refcnt;
};
struct kvm_event_stats {
@ -145,6 +149,42 @@ extern const char *vcpu_id_str;
extern const char *kvm_exit_reason;
extern const char *kvm_entry_trace;
extern const char *kvm_exit_trace;
static inline struct kvm_info *kvm_info__get(struct kvm_info *ki)
{
if (ki)
refcount_inc(&ki->refcnt);
return ki;
}
static inline void kvm_info__put(struct kvm_info *ki)
{
if (ki && refcount_dec_and_test(&ki->refcnt))
free(ki);
}
static inline void __kvm_info__zput(struct kvm_info **ki)
{
kvm_info__put(*ki);
*ki = NULL;
}
#define kvm_info__zput(ki) __kvm_info__zput(&ki)
static inline struct kvm_info *kvm_info__new(void)
{
struct kvm_info *ki;
ki = zalloc(sizeof(*ki));
if (ki)
refcount_set(&ki->refcnt, 1);
return ki;
}
#else /* HAVE_KVM_STAT_SUPPORT */
// We use this unconditionally in hists__findnew_entry() and hist_entry__delete()
#define kvm_info__zput(ki) do { } while (0)
#endif /* HAVE_KVM_STAT_SUPPORT */
extern int kvm_add_default_arch_event(int *argc, const char **argv);