[PATCH net-next 7/9] net: bcmgenet: relax lock constraints to reduce IRQ latency

[Doug Berger]

Since the ring locks are not used in a hard IRQ context it is often
not necessary to disable global IRQs while waiting on a lock.

Using less restrictive lock and unlock calls improves the real-time
responsiveness of the system.

Signed-off-by: Doug Berger 
---
 drivers/net/ethernet/broadcom/genet/bcmgenet.c | 25 ++---
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c 
b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index 747224714394..91f52c1b5108 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -1405,11 +1405,10 @@ static unsigned int bcmgenet_tx_reclaim(struct 
net_device *dev,
struct bcmgenet_tx_ring *ring)
 {
unsigned int released;
-   unsigned long flags;
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock_bh(>lock);
released = __bcmgenet_tx_reclaim(dev, ring);
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock_bh(>lock);
 
return released;
 }
@@ -1420,15 +1419,14 @@ static int bcmgenet_tx_poll(struct napi_struct *napi, 
int budget)
container_of(napi, struct bcmgenet_tx_ring, napi);
unsigned int work_done = 0;
struct netdev_queue *txq;
-   unsigned long flags;
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock(>lock);
work_done = __bcmgenet_tx_reclaim(ring->priv->dev, ring);
if (ring->free_bds > (MAX_SKB_FRAGS + 1)) {
txq = netdev_get_tx_queue(ring->priv->dev, ring->queue);
netif_tx_wake_queue(txq);
}
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock(>lock);
 
if (work_done == 0) {
napi_complete(napi);
@@ -1523,7 +1521,6 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, 
struct net_device *dev)
struct bcmgenet_tx_ring *ring = NULL;
struct enet_cb *tx_cb_ptr;
struct netdev_queue *txq;
-   unsigned long flags = 0;
int nr_frags, index;
dma_addr_t mapping;
unsigned int size;
@@ -1550,7 +1547,7 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, 
struct net_device *dev)
 
nr_frags = skb_shinfo(skb)->nr_frags;
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock(>lock);
if (ring->free_bds <= (nr_frags + 1)) {
if (!netif_tx_queue_stopped(txq)) {
netif_tx_stop_queue(txq);
@@ -1645,7 +1642,7 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, 
struct net_device *dev)
bcmgenet_tdma_ring_writel(priv, ring->index,
  ring->prod_index, TDMA_PROD_INDEX);
 out:
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock(>lock);
 
return ret;
 
@@ -2520,17 +2517,16 @@ static int bcmgenet_init_dma(struct bcmgenet_priv *priv)
 /* Interrupt bottom half */
 static void bcmgenet_irq_task(struct work_struct *work)
 {
-   unsigned long flags;
unsigned int status;
struct bcmgenet_priv *priv = container_of(
work, struct bcmgenet_priv, bcmgenet_irq_work);
 
netif_dbg(priv, intr, priv->dev, "%s\n", __func__);
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock_irq(>lock);
status = priv->irq0_stat;
priv->irq0_stat = 0;
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock_irq(>lock);
 
/* Link UP/DOWN event */
if (status & UMAC_IRQ_LINK_EVENT)
@@ -2927,7 +2923,6 @@ static void bcmgenet_dump_tx_queue(struct 
bcmgenet_tx_ring *ring)
u32 p_index, c_index, intsts, intmsk;
struct netdev_queue *txq;
unsigned int free_bds;
-   unsigned long flags;
bool txq_stopped;
 
if (!netif_msg_tx_err(priv))
@@ -2935,7 +2930,7 @@ static void bcmgenet_dump_tx_queue(struct 
bcmgenet_tx_ring *ring)
 
txq = netdev_get_tx_queue(priv->dev, ring->queue);
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock(>lock);
if (ring->index == DESC_INDEX) {
intsts = ~bcmgenet_intrl2_0_readl(priv, INTRL2_CPU_MASK_STATUS);
intmsk = UMAC_IRQ_TXDMA_DONE | UMAC_IRQ_TXDMA_MBDONE;
@@ -2947,7 +2942,7 @@ static void bcmgenet_dump_tx_queue(struct 
bcmgenet_tx_ring *ring)
p_index = bcmgenet_tdma_ring_readl(priv, ring->index, TDMA_PROD_INDEX);
txq_stopped = netif_tx_queue_stopped(txq);
free_bds = ring->free_bds;
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock(>lock);
 
netif_err(priv, tx_err, priv->dev, "Ring %d queue %d status summary\n"
  "TX queue status: %s, interrupts: %s\n"
-- 
2.14.1

[PATCH net-next 7/9] net: bcmgenet: relax lock constraints to reduce IRQ latency

[Doug Berger]

Since the ring locks are not used in a hard IRQ context it is often
not necessary to disable global IRQs while waiting on a lock.

Using less restrictive lock and unlock calls improves the real-time
responsiveness of the system.

Signed-off-by: Doug Berger 
---
 drivers/net/ethernet/broadcom/genet/bcmgenet.c | 25 ++---
 1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c 
b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
index 747224714394..91f52c1b5108 100644
--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
@@ -1405,11 +1405,10 @@ static unsigned int bcmgenet_tx_reclaim(struct 
net_device *dev,
struct bcmgenet_tx_ring *ring)
 {
unsigned int released;
-   unsigned long flags;
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock_bh(>lock);
released = __bcmgenet_tx_reclaim(dev, ring);
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock_bh(>lock);
 
return released;
 }
@@ -1420,15 +1419,14 @@ static int bcmgenet_tx_poll(struct napi_struct *napi, 
int budget)
container_of(napi, struct bcmgenet_tx_ring, napi);
unsigned int work_done = 0;
struct netdev_queue *txq;
-   unsigned long flags;
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock(>lock);
work_done = __bcmgenet_tx_reclaim(ring->priv->dev, ring);
if (ring->free_bds > (MAX_SKB_FRAGS + 1)) {
txq = netdev_get_tx_queue(ring->priv->dev, ring->queue);
netif_tx_wake_queue(txq);
}
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock(>lock);
 
if (work_done == 0) {
napi_complete(napi);
@@ -1523,7 +1521,6 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, 
struct net_device *dev)
struct bcmgenet_tx_ring *ring = NULL;
struct enet_cb *tx_cb_ptr;
struct netdev_queue *txq;
-   unsigned long flags = 0;
int nr_frags, index;
dma_addr_t mapping;
unsigned int size;
@@ -1550,7 +1547,7 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, 
struct net_device *dev)
 
nr_frags = skb_shinfo(skb)->nr_frags;
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock(>lock);
if (ring->free_bds <= (nr_frags + 1)) {
if (!netif_tx_queue_stopped(txq)) {
netif_tx_stop_queue(txq);
@@ -1645,7 +1642,7 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, 
struct net_device *dev)
bcmgenet_tdma_ring_writel(priv, ring->index,
  ring->prod_index, TDMA_PROD_INDEX);
 out:
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock(>lock);
 
return ret;
 
@@ -2520,17 +2517,16 @@ static int bcmgenet_init_dma(struct bcmgenet_priv *priv)
 /* Interrupt bottom half */
 static void bcmgenet_irq_task(struct work_struct *work)
 {
-   unsigned long flags;
unsigned int status;
struct bcmgenet_priv *priv = container_of(
work, struct bcmgenet_priv, bcmgenet_irq_work);
 
netif_dbg(priv, intr, priv->dev, "%s\n", __func__);
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock_irq(>lock);
status = priv->irq0_stat;
priv->irq0_stat = 0;
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock_irq(>lock);
 
/* Link UP/DOWN event */
if (status & UMAC_IRQ_LINK_EVENT)
@@ -2927,7 +2923,6 @@ static void bcmgenet_dump_tx_queue(struct 
bcmgenet_tx_ring *ring)
u32 p_index, c_index, intsts, intmsk;
struct netdev_queue *txq;
unsigned int free_bds;
-   unsigned long flags;
bool txq_stopped;
 
if (!netif_msg_tx_err(priv))
@@ -2935,7 +2930,7 @@ static void bcmgenet_dump_tx_queue(struct 
bcmgenet_tx_ring *ring)
 
txq = netdev_get_tx_queue(priv->dev, ring->queue);
 
-   spin_lock_irqsave(>lock, flags);
+   spin_lock(>lock);
if (ring->index == DESC_INDEX) {
intsts = ~bcmgenet_intrl2_0_readl(priv, INTRL2_CPU_MASK_STATUS);
intmsk = UMAC_IRQ_TXDMA_DONE | UMAC_IRQ_TXDMA_MBDONE;
@@ -2947,7 +2942,7 @@ static void bcmgenet_dump_tx_queue(struct 
bcmgenet_tx_ring *ring)
p_index = bcmgenet_tdma_ring_readl(priv, ring->index, TDMA_PROD_INDEX);
txq_stopped = netif_tx_queue_stopped(txq);
free_bds = ring->free_bds;
-   spin_unlock_irqrestore(>lock, flags);
+   spin_unlock(>lock);
 
netif_err(priv, tx_err, priv->dev, "Ring %d queue %d status summary\n"
  "TX queue status: %s, interrupts: %s\n"
-- 
2.14.1