cpuview: start to use interruptible lock primitives

Let's start using fuse-interruptible locks in cpuview.
It's better to start from one place instead of converting everything
at once to prevent global degradations.

Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>

diff --git a/src/proc_cpuview.c b/src/proc_cpuview.c
index f5464de7991c163e8bdc8cbdc77b1c5e17928520..14afdd0bdb50a7f7d598761c46b2f6d3b6ca1c35 100644 (file)
--- a/src/proc_cpuview.c
+++ b/src/proc_cpuview.c
@@ -286,7 +286,8 @@ static void prune_proc_stat_history(void)
        time_t now = time(NULL);
 
        for (int i = 0; i < CPUVIEW_HASH_SIZE; i++) {
-               pthread_rwlock_wrlock(&proc_stat_history[i]->lock);
+               if (rwlock_wrlock_interruptible(&proc_stat_history[i]->lock))
+                       continue;
 
                if ((proc_stat_history[i]->lastcheck + PROC_STAT_PRUNE_INTERVAL) > now) {
                        pthread_rwlock_unlock(&proc_stat_history[i]->lock);
@@ -308,7 +309,8 @@ static struct cg_proc_stat *find_proc_stat_node(struct cg_proc_stat_head *head,
        struct cg_proc_stat *node;
 
        prune_proc_stat_history();
-       pthread_rwlock_rdlock(&head->lock);
+       if (rwlock_rdlock_interruptible(&head->lock))
+               return NULL;
 
        if (!head->next) {
                pthread_rwlock_unlock(&head->lock);
@@ -319,7 +321,13 @@ static struct cg_proc_stat *find_proc_stat_node(struct cg_proc_stat_head *head,
 
        do {
                if (strcmp(cg, node->cg) == 0) {
-                       pthread_mutex_lock(&node->lock);
+                       /*
+                        * If we are failed to take a lock OR
+                        * fuse request was interrupted then
+                        * just return NULL and exit gracefully.
+                        */
+                       if (mutex_lock_interruptible(&node->lock))
+                               node = NULL;
                        goto out;
                }
        } while ((node = node->next));
@@ -340,6 +348,10 @@ static struct cg_proc_stat *find_or_create_proc_stat_node(struct cpuacct_usage *
 
        node = find_proc_stat_node(head, cg);
        if (!node) {
+               /* safe place to exit */
+               if (fuse_interrupted())
+                       return NULL;
+
                node = new_proc_stat_node(usage, cpu_count, cg);
                if (!node)
                        return NULL;