powertop segfault

perf.patch

commit 318dcc2daf1bf6f297eed022699c39354eab4699
gpg: Signature made Tue 23 Apr 2019 06:09:08 AM PDT
gpg:                using RSA key F6CC1F4DF325EACBBE2532481F299543498470BA
gpg:                issuer "[email protected]"
gpg: Good signature from "Justin Capella <[email protected]>" [ultimate]
Author: b1tninja <devnull@localhost>
Date:   Tue Apr 23 06:09:08 2019 -0700

    Check that perf event is properly allocated, combine constructor

diff --git a/src/perf/perf.cpp b/src/perf/perf.cpp
index 9ed0ba8..c9af036 100644
--- a/src/perf/perf.cpp
+++ b/src/perf/perf.cpp
@@ -138,7 +138,8 @@ void perf_event::create_perf_event(char *eventname, int _cpu)
 	ret = ioctl(perf_fd, PERF_EVENT_IOC_ENABLE, 0);
 
 	if (ret < 0) {
-		fprintf(stderr, "failed to enable perf \n");
+		fprintf(stderr, "failed to enable perf\n");
+		return;
 	}
 
 	pc = (perf_event_mmap_page *)perf_mmap;
@@ -192,13 +193,9 @@ static void allocate_pevent(void)
 
 perf_event::perf_event(const char *event_name, int _cpu, int buffer_size)
 {
-	allocate_pevent();
-	name = NULL;
-	perf_fd = -1;
+	perf_event();
 	bufsize = buffer_size;
 	cpu = _cpu;
-	perf_mmap = NULL;
-	trace_type = 0;
 	set_event_name(event_name);
 }
 
@@ -208,7 +205,9 @@ perf_event::perf_event(void)
 	name = NULL;
 	perf_fd = -1;
 	bufsize = 128;
-	perf_mmap = NULL;
+	perf_mmap = MAP_FAILED;
+	data_mmap = MAP_FAILED;
+	pc = NULL;
 	cpu = 0;
 	trace_type = 0;
 }
@@ -230,7 +229,7 @@ void perf_event::process(void *cookie)
 {
 	struct perf_event_header *header;
 
-	if (perf_fd < 0)
+	if (perf_fd < 0 || MAP_FAILED == perf_mmap || NULL == pc)
 		return;
 
 	while (pc->data_tail != pc->data_head ) {
@@ -255,10 +254,11 @@ void perf_event::process(void *cookie)
 
 void perf_event::clear(void)
 {
-	if (perf_mmap) {
+	pc = NULL;
+	if (MAP_FAILED != perf_mmap) {
 //		memset(perf_mmap, 0, (bufsize)*getpagesize());
 		munmap(perf_mmap, (bufsize+1)*getpagesize());
-		perf_mmap = NULL;
+		perf_mmap = MAP_FAILED;
 	}
 	if (perf_fd != -1)
 		close(perf_fd);

For debugging reasons, figured it best to just check the other variables are not set-- instead of relying on the fd being negative by clearing many... may help with debugging, may reveal other locations making false assumptions based around perf_fd