[Intel-gfx] [PATCH i-g-t v2] intel_gpu_top: Fix cleanup on old kernels / unsupported GPU

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursu...@intel.com>

Avoid trying to dereference null engines on exit when there are either
none which are supported, or kernel does not have i915 PMU support.

Also fix a memory leak on the same failure path just so Valgrind runs are
quite.

v2:
 * Fix a memory leak in the same failure mode too.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Acked-by: Nirmoy Das <nirmoy....@intel.com> # v1
---
 tools/intel_gpu_top.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/tools/intel_gpu_top.c b/tools/intel_gpu_top.c
index 7aa233570463..0a1de41b3374 100644
--- a/tools/intel_gpu_top.c
+++ b/tools/intel_gpu_top.c
@@ -340,7 +340,7 @@ static struct engines *discover_engines(char *device)
 
        d = opendir(sysfs_root);
        if (!d)
-               return NULL;
+               goto err;
 
        while ((dent = readdir(d)) != NULL) {
                const char *endswith = "-busy";
@@ -423,10 +423,8 @@ static struct engines *discover_engines(char *device)
        }
 
        if (ret) {
-               free(engines);
                errno = ret;
-
-               return NULL;
+               goto err;
        }
 
        qsort(engine_ptr(engines, 0), engines->num_engines,
@@ -435,6 +433,11 @@ static struct engines *discover_engines(char *device)
        engines->root = d;
 
        return engines;
+
+err:
+       free(engines);
+
+       return NULL;
 }
 
 static void free_engines(struct engines *engines)
@@ -448,6 +451,9 @@ static void free_engines(struct engines *engines)
        };
        unsigned int i;
 
+       if (!engines)
+               return;
+
        for (pmu = &free_list[0]; *pmu; pmu++) {
                if ((*pmu)->present)
                        free((char *)(*pmu)->units);
@@ -2568,7 +2574,7 @@ int main(int argc, char **argv)
                        "Failed to detect engines! (%s)\n(Kernel 4.16 or newer 
is required for i915 PMU support.)\n",
                        strerror(errno));
                ret = EXIT_FAILURE;
-               goto err;
+               goto err_engines;
        }
 
        ret = pmu_init(engines);
@@ -2585,7 +2591,7 @@ int main(int argc, char **argv)
 "More information can be found at 'Perf events and tool security' document:\n"
 "https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html\n";);
                ret = EXIT_FAILURE;
-               goto err;
+               goto err_pmu;
        }
 
        ret = EXIT_SUCCESS;
@@ -2699,8 +2705,9 @@ int main(int argc, char **argv)
                free_clients(clients);
 
        free(codename);
-err:
+err_pmu:
        free_engines(engines);
+err_engines:
        free(pmu_device);
 exit:
        igt_devices_free();
-- 
2.34.1