From a8255243254baeee796eae28c1c4b328b7b57d92 Mon Sep 17 00:00:00 2001
From: Con Kolivas <kernel@kolivas.org>
Date: Sat, 8 Feb 2014 11:09:11 +1100
Subject: [PATCH] We shouldn't block on no work situations directly from the
 getwork scheduler itself.

---
 sgminer.c | 48 ++++++++++++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/sgminer.c b/sgminer.c
index c1c4774c..d287e182 100644
--- a/sgminer.c
+++ b/sgminer.c
@@ -5713,29 +5713,35 @@ static void pool_resus(struct pool *pool)
 		applog(LOG_INFO, "%s alive", pool->poolname);
 }
 
-static struct work *hash_pop(void)
+/* If this is called non_blocking, it will return NULL for work so that must
+ * be handled. */
+static struct work *hash_pop(bool blocking)
 {
 	struct work *work = NULL, *tmp;
 	int hc;
 
 	mutex_lock(stgd_lock);
-	while (!HASH_COUNT(staged_work)) {
-		struct timespec then;
-		struct timeval now;
-		int rc;
+	if (!HASH_COUNT(staged_work)) {
+		if (!blocking)
+			goto out_unlock;
+		do {
+			struct timespec then;
+			struct timeval now;
+			int rc;
 
-		cgtime(&now);
-		then.tv_sec = now.tv_sec + 10;
-		then.tv_nsec = now.tv_usec * 1000;
-		pthread_cond_signal(&gws_cond);
-		rc = pthread_cond_timedwait(&getq->cond, stgd_lock, &then);
-		/* Check again for !no_work as multiple threads may be
-			* waiting on this condition and another may set the
-			* bool separately. */
-		if (rc && !no_work) {
-			no_work = true;
-			applog(LOG_WARNING, "Waiting for work to be available from pools.");
-		}
+			cgtime(&now);
+			then.tv_sec = now.tv_sec + 10;
+			then.tv_nsec = now.tv_usec * 1000;
+			pthread_cond_signal(&gws_cond);
+			rc = pthread_cond_timedwait(&getq->cond, stgd_lock, &then);
+			/* Check again for !no_work as multiple threads may be
+				* waiting on this condition and another may set the
+				* bool separately. */
+			if (rc && !no_work) {
+				no_work = true;
+				applog(LOG_WARNING, "Waiting for work to be available from pools.");
+			}
+		} while (!HASH_COUNT(staged_work));
 	}
 
 	if (no_work) {
@@ -5764,6 +5770,7 @@ static struct work *hash_pop(void)
 
 	/* Keep track of last getwork grabbed */
 	last_getwork = time(NULL);
+out_unlock:
 	mutex_unlock(stgd_lock);
 
 	return work;
@@ -5918,7 +5925,7 @@ struct work *get_work(struct thr_info *thr, const int thr_id)
 	applog(LOG_DEBUG, "Popping work from get queue to get work");
 	diff_t = time(NULL);
 	while (!work) {
-		work = hash_pop();
+		work = hash_pop(true);
 		if (stale_work(work, false)) {
 			discard_work(work);
 			work = NULL;
@@ -8178,8 +8185,9 @@ begin_bench:
 			/* Keeps slowly generating work even if it's not being
 			 * used to keep last_getwork incrementing and to see
 			 * if pools are still alive. */
-			work = hash_pop();
-			discard_work(work);
+			work = hash_pop(false);
+			if (work)
+				discard_work(work);
 			continue;
 		}