[PATCH PM-QA] heat_cpu: fix race condition

[Mohammad Merajul Islam Molla]

fixes race condition that exists between do_loop() and sched_setaffinity() on
android. due to synchronization problem, sched_setaffinity() was setting
affinity for thr_id 0 randomly.

also, allocate the thr_id's dynamically instead of fixed array size 3.

tested on Linaro Android 14.04.

Signed-off-by: Mohammad Merajul Islam Molla <meraj.eni...@gmail.com>
---
 utils/heat_cpu.c | 35 +++++++++++++++++++----------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/utils/heat_cpu.c b/utils/heat_cpu.c
index 02e0b6d..716cd56 100644
--- a/utils/heat_cpu.c
+++ b/utils/heat_cpu.c
@@ -47,17 +47,14 @@
 #include <string.h>
 #include <math.h>

-#define NR_THREAD 3
-
 int cont = 1;
 int cpu_index;

 long long a = 1, c = 1;
 float f = M_PI;
-pid_t thr_id[NR_THREAD];
+pid_t *thr_id;
 int moderate_inst;

-
 #ifdef ANDROID
 int                 conditionMet;
 pthread_cond_t      cond  = PTHREAD_COND_INITIALIZER;
@@ -72,11 +69,11 @@ void *do_loop(void *data)
        a = 1;
        c = 1;
 #ifdef ANDROID
+       pthread_mutex_lock(&mutex);
        long int thread = (long int) data;
        thr_id[thread] = gettid();
-       pthread_mutex_lock(&mutex);
-       while (!conditionMet)
-               pthread_cond_wait(&cond, &mutex);
+       conditionMet = 1;
+       pthread_cond_broadcast(&cond);
        pthread_mutex_unlock(&mutex);
 #endif

@@ -112,6 +109,12 @@ int main(int arg_count, char *argv[])
                }
        }

+       thr_id = (pid_t *) calloc(num_cpus, sizeof(pid_t));
+       if (thr_id == NULL) {
+               printf("ERROR: out of memory\n");
+               return -1;
+       }
+
        /* clear out cpus */
        CPU_ZERO(&cpuset);

@@ -161,8 +164,7 @@ int main(int arg_count, char *argv[])
                        return ret;
                }
 #endif
-       CPU_CLR(i, &cpuset);
-
+               CPU_CLR(i, &cpuset);
        }

        for (i = 0; i < num_cpus; i++) {
@@ -176,23 +178,24 @@ int main(int arg_count, char *argv[])
                CPU_ZERO(&cpuset);
                CPU_SET(i, &cpuset);

+               pthread_mutex_lock(&mutex);
+               while (!conditionMet)
+                       pthread_cond_wait(&cond, &mutex);
+
                ret = sched_setaffinity(thr_id[i], sizeof(cpuset), &cpuset);
                if (ret) {
                        printf("Error setting affinity on pthread th_id\n");
                        printf("Error: %s\n", strerror(ret));
                        return ret;
                }
-#endif
-       }

-#ifdef ANDROID
-       pthread_mutex_lock(&mutex);
-       conditionMet = 1;
-       pthread_cond_broadcast(&cond);
-       pthread_mutex_unlock(&mutex);
+               conditionMet = 0;
+               pthread_mutex_unlock(&mutex);
 #endif
+       }

        while (1)
                sleep(1);
+
        return 0;
 }
--
1.8.1.2



-- 
Thanks,
-Meraj

_______________________________________________
linaro-dev mailing list
linaro-dev@lists.linaro.org
http://lists.linaro.org/mailman/listinfo/linaro-dev