[RFC PATCH 12/13] powerpc/vas: Display process stuck message

[Haren Myneni]

Process can not close send window until all requests are processed.
Means wait until window state is not busy and send credits are
returned. Display debug message in case taking longer to close the
window.

Signed-off-by: Haren Myneni <haren at us.ibm.com>
---
 arch/powerpc/platforms/powernv/vas-window.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
index 85a60ac..df53841 100644
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -1156,6 +1156,7 @@ static void poll_window_credits(struct vas_window *window)
 {
 	u64 val;
 	int creds, mode;
+	int count = 0;
 
 	val = read_hvwc_reg(window, VREG(WINCTL));
 	if (window->tx_win)
@@ -1174,10 +1175,25 @@ static void poll_window_credits(struct vas_window *window)
 		creds = GET_FIELD(VAS_LRX_WCRED, val);
 	}
 
+	/*
+	 * Takes around few microseconds to complete all pending requests
+	 * and return credits.
+	 * TODO: Issue CRB Kill to stop all pending requests. Need only
+	 *       if there is a bug in NX or fault handling in kernel.
+	 */
 	if (creds < window->wcreds_max) {
 		val = 0;
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		schedule_timeout(msecs_to_jiffies(10));
+		count++;
+		/*
+		 * Process can not close send window until all credits are
+		 * returned.
+		 */
+		if (!(count % 10000))
+			pr_debug("%s() pid %d stuck? retries %d\n", __func__,
+				window->pid, count);
+
 		goto retry;
 	}
 }
@@ -1191,6 +1207,7 @@ static void poll_window_busy_state(struct vas_window *window)
 {
 	int busy;
 	u64 val;
+	int count = 0;
 
 retry:
 	val = read_hvwc_reg(window, VREG(WIN_STATUS));
@@ -1199,6 +1216,15 @@ static void poll_window_busy_state(struct vas_window *window)
 		val = 0;
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		schedule_timeout(msecs_to_jiffies(5));
+		count++;
+		/*
+		 * Takes around 5 microseconds to process all pending
+		 * requests.
+		 */
+		if (!(count % 10000))
+			pr_debug("%s() pid %d stuck? retries %d\n", __func__,
+				window->pid, count);
+
 		goto retry;
 	}
 }
-- 
1.8.3.1