[PATCH 05/10] net: emac: mal: replace busy-wait in mal_poll_disable with wait_event

[Rosen Penev]

Replace the msleep(1) busy-wait loop in mal_poll_disable() with
a proper wait_event/wake_up mechanism. Add wait_queue_head_t to
struct mal_commac, initialize it in mal_poll_add(), and wake
waiters in mal_poll_enable().

Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
---
 drivers/net/ethernet/ibm/emac/mal.c | 7 +++++--
 drivers/net/ethernet/ibm/emac/mal.h | 3 +++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ibm/emac/mal.c b/drivers/net/ethernet/ibm/emac/mal.c
index 82d502d576ee..d12a376f69fd 100644
--- a/drivers/net/ethernet/ibm/emac/mal.c
+++ b/drivers/net/ethernet/ibm/emac/mal.c
@@ -176,6 +176,8 @@ void mal_poll_add(struct mal_instance *mal, struct mal_commac *commac)
 
 	MAL_DBG(mal, "poll_add(%p)" NL, commac);
 
+	init_waitqueue_head(&commac->poll_wait);
+
 	/* starts disabled */
 	set_bit(MAL_COMMAC_POLL_DISABLED, &commac->flags);
 
@@ -371,8 +373,8 @@ static irqreturn_t mal_int(int irq, void *dev_instance)
 void mal_poll_disable(struct mal_instance *mal, struct mal_commac *commac)
 {
 	/* Spinlock-type semantics: only one caller disable poll at a time */
-	while (test_and_set_bit(MAL_COMMAC_POLL_DISABLED, &commac->flags))
-		msleep(1);
+	wait_event(commac->poll_wait,
+		   !test_and_set_bit(MAL_COMMAC_POLL_DISABLED, &commac->flags));
 
 	/* Synchronize with the MAL NAPI poller */
 	napi_synchronize(&mal->napi);
@@ -382,6 +384,7 @@ void mal_poll_enable(struct mal_instance *mal, struct mal_commac *commac)
 {
 	smp_wmb();
 	clear_bit(MAL_COMMAC_POLL_DISABLED, &commac->flags);
+	wake_up(&commac->poll_wait);
 
 	/* Feels better to trigger a poll here to catch up with events that
 	 * may have happened on this channel while disabled. It will most
diff --git a/drivers/net/ethernet/ibm/emac/mal.h b/drivers/net/ethernet/ibm/emac/mal.h
index e0ddc41186a2..bd52bb41adee 100644
--- a/drivers/net/ethernet/ibm/emac/mal.h
+++ b/drivers/net/ethernet/ibm/emac/mal.h
@@ -19,6 +19,8 @@
 #ifndef __IBM_NEWEMAC_MAL_H
 #define __IBM_NEWEMAC_MAL_H
 
+#include <linux/wait.h>
+
 /*
  * There are some variations on the MAL, we express them in this driver as
  * MAL Version 1 and 2 though that doesn't match any IBM terminology.
@@ -172,6 +174,7 @@ struct mal_commac {
 	void			*dev;
 	struct list_head	poll_list;
 	long       		flags;
+	wait_queue_head_t	poll_wait;
 #define MAL_COMMAC_RX_STOPPED		0
 #define MAL_COMMAC_POLL_DISABLED	1
 	u32			tx_chan_mask;
-- 
2.54.0