From: Eric Wong <normalperson@yhbt.net>
Date: Tue, 24 Jun 2014 01:20:31 +0000 (+0000)
Subject: rculfhash: handle pthread_create failures
X-Git-Tag: v0.8.5~3
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=ab4b644ea95d7bd129d72cef888b01f940946e68;p=userspace-rcu.git

rculfhash: handle pthread_create failures

Like calloc, pthread_create may fail with EAGAIN due to a lack
of resources.  Account for that and gracefully continue.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/rculfhash.c b/rculfhash.c
index 2a45045..8a8ede7 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -1171,7 +1171,7 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
 		void (*fct)(struct cds_lfht *ht, unsigned long i,
 			unsigned long start, unsigned long len))
 {
-	unsigned long partition_len;
+	unsigned long partition_len, start = 0;
 	struct partition_resize_work *work;
 	int thread, ret;
 	unsigned long nr_threads;
@@ -1201,6 +1201,17 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
 		work[thread].fct = fct;
 		ret = pthread_create(&(work[thread].thread_id), ht->resize_attr,
 			partition_resize_thread, &work[thread]);
+		if (ret == EAGAIN) {
+			/*
+			 * Out of resources: wait and join the threads
+			 * we've created, then handle leftovers.
+			 */
+			dbg_printf("error spawning for resize, single-threading\n");
+			start = work[thread].start;
+			len -= start;
+			nr_threads = thread;
+			break;
+		}
 		assert(!ret);
 	}
 	for (thread = 0; thread < nr_threads; thread++) {
@@ -1208,10 +1219,17 @@ void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
 		assert(!ret);
 	}
 	free(work);
-	return;
+
+	/*
+	 * A pthread_create failure above will either lead in us having
+	 * no threads to join or starting at a non-zero offset,
+	 * fallback to single thread processing of leftovers.
+	 */
+	if (start == 0 && nr_threads > 0)
+		return;
 fallback:
 	ht->flavor->thread_online();
-	fct(ht, i, 0, len);
+	fct(ht, i, start, len);
 	ht->flavor->thread_offline();
 }