Commit f1e8f259 authored by Leo Yan's avatar Leo Yan Committed by Arnaldo Carvalho de Melo
Browse files

perf kvm: Reference count 'struct kvm_info' 



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: default avatarLeo Yan <leo.yan@linaro.org>
Acked-by: default avatarIan 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent ea15483e

tools/perf/builtin-kvm.c

+1 −2
Original line number Diff line number Diff line
@@ -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;

tools/perf/util/hist.c

+5 −0
Original line number Diff line number Diff line
@@ -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			 * become out-of-date due to an exec() or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);

tools/perf/util/kvm-stat.h

+40 −0
Original line number Diff line number Diff line
@@ -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);