From 7b9b0781146dde69378d53bafd3c8817fb8909e9 Mon Sep 17 00:00:00 2001
From: Con Kolivas <kernel@kolivas.org>
Date: Tue, 12 Jul 2011 19:19:00 +1000
Subject: [PATCH] Change get_work to use a timeout when trying to tq_pop as a
 sanity failsafe in case of unusual circumstances.

---
 main.c | 13 ++++++++++---
 util.c |  6 +++++-
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/main.c b/main.c
index 8d59f6c2..8d049fd7 100644
--- a/main.c
+++ b/main.c
@@ -1149,6 +1149,8 @@ static void flush_requests(bool longpoll)
 
 static bool get_work(struct work *work, bool queued)
 {
+	struct timeval now;
+	struct timespec abstime = {};
 	struct thr_info *thr = &thr_info[0];
 	struct work *work_heap;
 	bool ret = false;
@@ -1157,6 +1159,9 @@ static bool get_work(struct work *work, bool queued)
 	getwork_requested++;
 
 retry:
+	gettimeofday(&now, NULL);
+	abstime.tv_sec = now.tv_sec + 60;
+
 	if (unlikely(!queued && !queue_request())) {
 		applog(LOG_WARNING, "Failed to queue_request in get_work");
 		goto out;
@@ -1181,10 +1186,12 @@ retry:
 		applog(LOG_WARNING, "Resumed retrieving work from server");
 	}
 
-	/* wait for 1st response, or get cached response */
-	work_heap = tq_pop(thr->q, NULL);
+	/* Wait for 1st response, or get cached response. We really should
+	 * never time out on the pop request but something might go amiss :/
+	 */
+	work_heap = tq_pop(thr->q, &abstime);
 	if (unlikely(!work_heap)) {
-		applog(LOG_WARNING, "Failed to tq_pop in get_work");
+		applog(LOG_INFO, "Failed to tq_pop in get_work");
 		goto out;
 	}
 	dec_queued();
diff --git a/util.c b/util.c
index 2be8a3b4..5205c348 100644
--- a/util.c
+++ b/util.c
@@ -21,6 +21,7 @@
 #include <curl/curl.h>
 #include <time.h>
 #include <curses.h>
+#include <errno.h>
 #include "miner.h"
 #include "elist.h"
 
@@ -559,8 +560,11 @@ void *tq_pop(struct thread_q *tq, const struct timespec *abstime)
 		rc = pthread_cond_timedwait(&tq->cond, &tq->mutex, abstime);
 	else
 		rc = pthread_cond_wait(&tq->cond, &tq->mutex);
-	if (rc)
+	if (unlikely(rc)) {
+		if (rc == ETIMEDOUT)
+			applog(LOG_WARNING, "Timed out waiting in tq_pop");
 		goto out;
+	}
 	if (list_empty(&tq->q))
 		goto out;