[PATCH 0/4] wireless: Use irqsave in USB's complete callback

[PATCH 0/4] wireless: Use irqsave in USB's complete callback

[Sebastian Andrzej Siewior]

This is about using _irqsave() primitives in the completion callback in order
to get rid of local_irq_save() in __usb_hcd_giveback_urb().

Sebastian

[PATCH 1/4] ath9k: use irqsave() in USB's complete callback

[Sebastian Andrzej Siewior]

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

Cc: QCA ath9k Development <ath9k-devel-A+ZNKFmMK5xy9aJCnZT0Uw@public.gmane.org>
Cc: Kalle Valo <kvalo-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
Cc: "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
Cc: linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
---
 drivers/net/wireless/ath/ath9k/hif_usb.c      |  7 ++++---
 drivers/net/wireless/ath/ath9k/htc_drv_txrx.c |  9 +++++----
 drivers/net/wireless/ath/ath9k/wmi.c          | 11 ++++++-----
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index cb0eef13af1c..fb649d85b8fc 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -138,6 +138,7 @@ static void hif_usb_mgmt_cb(struct urb *urb)
 {
 	struct cmd_buf *cmd = (struct cmd_buf *)urb->context;
 	struct hif_device_usb *hif_dev;
+	unsigned long flags;
 	bool txok = true;
 
 	if (!cmd || !cmd->skb || !cmd->hif_dev)
@@ -158,14 +159,14 @@ static void hif_usb_mgmt_cb(struct urb *urb)
 		 * If the URBs are being flushed, no need to complete
 		 * this packet.
 		 */
-		spin_lock(&hif_dev->tx.tx_lock);
+		spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
 		if (hif_dev->tx.flags & HIF_USB_TX_FLUSH) {
-			spin_unlock(&hif_dev->tx.tx_lock);
+			spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags);
 			dev_kfree_skb_any(cmd->skb);
 			kfree(cmd);
 			return;
 		}
-		spin_unlock(&hif_dev->tx.tx_lock);
+		spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags);
 
 		break;
 	default:
diff --git a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
index 585736a837ed..799010ed04e0 100644
--- a/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
+++ b/drivers/net/wireless/ath/ath9k/htc_drv_txrx.c
@@ -1107,25 +1107,26 @@ void ath9k_htc_rxep(void *drv_priv, struct sk_buff *skb,
 	struct ath_hw *ah = priv->ah;
 	struct ath_common *common = ath9k_hw_common(ah);
 	struct ath9k_htc_rxbuf *rxbuf = NULL, *tmp_buf = NULL;
+	unsigned long flags;
 
-	spin_lock(&priv->rx.rxbuflock);
+	spin_lock_irqsave(&priv->rx.rxbuflock, flags);
 	list_for_each_entry(tmp_buf, &priv->rx.rxbuf, list) {
 		if (!tmp_buf->in_process) {
 			rxbuf = tmp_buf;
 			break;
 		}
 	}
-	spin_unlock(&priv->rx.rxbuflock);
+	spin_unlock_irqrestore(&priv->rx.rxbuflock, flags);
 
 	if (rxbuf == NULL) {
 		ath_dbg(common, ANY, "No free RX buffer\n");
 		goto err;
 	}
 
-	spin_lock(&priv->rx.rxbuflock);
+	spin_lock_irqsave(&priv->rx.rxbuflock, flags);
 	rxbuf->skb = skb;
 	rxbuf->in_process = true;
-	spin_unlock(&priv->rx.rxbuflock);
+	spin_unlock_irqrestore(&priv->rx.rxbuflock, flags);
 
 	tasklet_schedule(&priv->rx_tasklet);
 	return;
diff --git a/drivers/net/wireless/ath/ath9k/wmi.c b/drivers/net/wireless/ath/ath9k/wmi.c
index b0b5579b7560..d1f6710ca63b 100644
--- a/drivers/net/wireless/ath/ath9k/wmi.c
+++ b/drivers/net/wireless/ath/ath9k/wmi.c
@@ -209,6 +209,7 @@ static void ath9k_wmi_ctrl_rx(void *priv, struct sk_buff *skb,
 {
 	struct wmi *wmi = priv;
 	struct wmi_cmd_hdr *hdr;
+	unsigned long flags;
 	u16 cmd_id;
 
 	if (unlikely(wmi->stopped))
@@ -218,20 +219,20 @@ static void ath9k_wmi_ctrl_rx(void *priv, struct sk_buff *skb,
 	cmd_id = be16_to_cpu(hdr->command_id);
 
 	if (cmd_id & 0x1000) {
-		spin_lock(&wmi->wmi_lock);
+		spin_lock_irqsave(&wmi->wmi_lock, flags);
 		__skb_queue_tail(&wmi->wmi_event_queue, skb);
-		spin_unlock(&wmi->wmi_lock);
+		spin_unlock_irqrestore(&wmi->wmi_lock, flags);
 		tasklet_schedule(&wmi->wmi_event_tasklet);
 		return;
 	}
 
 	/* Check if there has been a timeout. */
-	spin_lock(&wmi->wmi_lock);
+	spin_lock_irqsave(&wmi->wmi_lock, flags);
 	if (be16_to_cpu(hdr->seq_no) != wmi->last_seq_id) {
-		spin_unlock(&wmi->wmi_lock);
+		spin_unlock_irqrestore(&wmi->wmi_lock, flags);
 		goto free_skb;
 	}
-	spin_unlock(&wmi->wmi_lock);
+	spin_unlock_irqrestore(&wmi->wmi_lock, flags);
 
 	/* WMI command response */
 	ath9k_wmi_rsp_callback(wmi, skb);
-- 
2.17.1

Re: [1/4] ath9k: use irqsave() in USB's complete callback

[Kalle Valo]

Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:

> The USB completion callback does not disable interrupts while acquiring
> the lock. We want to remove the local_irq_disable() invocation from
> __usb_hcd_giveback_urb() and therefore it is required for the callback
> handler to disable the interrupts while acquiring the lock.
> The callback may be invoked either in IRQ or BH context depending on the
> USB host controller.
> Use the _irqsave() variant of the locking primitives.
> 
> Cc: QCA ath9k Development <ath9k-devel@qca.qualcomm.com>
> Cc: Kalle Valo <kvalo@codeaurora.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: linux-wireless@vger.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

Patch applied to ath-next branch of ath.git, thanks.

84a0d4669c8f ath9k: use irqsave() in USB's complete callback

-- 
https://patchwork.kernel.org/patch/10478601/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

[PATCH 3/4] libertas: use irqsave() in USB's complete callback

[Sebastian Andrzej Siewior]

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

I am removing the
	BUG_ON(!in_interrupt());

check because it serves no purpose. Running the completion callback in
BH context makes in_interrupt() still return true but the interrupts
could be enabled. The important part is that ->driver_lock is acquired
with disabled interrupts which is the case now.

Cc: Kalle Valo <kvalo-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
Cc: "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
Cc: libertas-dev-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Cc: linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
---
 drivers/net/wireless/marvell/libertas/if_usb.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas/if_usb.c b/drivers/net/wireless/marvell/libertas/if_usb.c
index ffea610f67e2..c67a8e7be310 100644
--- a/drivers/net/wireless/marvell/libertas/if_usb.c
+++ b/drivers/net/wireless/marvell/libertas/if_usb.c
@@ -614,6 +614,7 @@ static inline void process_cmdrequest(int recvlength, uint8_t *recvbuff,
 				      struct if_usb_card *cardp,
 				      struct lbs_private *priv)
 {
+	unsigned long flags;
 	u8 i;
 
 	if (recvlength > LBS_CMD_BUFFER_SIZE) {
@@ -623,9 +624,7 @@ static inline void process_cmdrequest(int recvlength, uint8_t *recvbuff,
 		return;
 	}
 
-	BUG_ON(!in_interrupt());

[PATCH 2/4] libertas_tf: use irqsave() in USB's complete callback

[Sebastian Andrzej Siewior]

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

I am removing the
	BUG_ON(!in_interrupt());

check because it serves no purpose. Running the completion callback in
BH context makes in_interrupt() still return true but the interrupts
could be enabled. The important part is that ->driver_lock is acquired
with disabled interrupts which is the case now.

Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/net/wireless/marvell/libertas_tf/if_usb.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas_tf/if_usb.c b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
index 5153922e7ce1..e92fc5001171 100644
--- a/drivers/net/wireless/marvell/libertas_tf/if_usb.c
+++ b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
@@ -603,6 +603,8 @@ static inline void process_cmdrequest(int recvlength, uint8_t *recvbuff,
 				      struct if_usb_card *cardp,
 				      struct lbtf_private *priv)
 {
+	unsigned long flags;
+
 	if (recvlength > LBS_CMD_BUFFER_SIZE) {
 		lbtf_deb_usbd(&cardp->udev->dev,
 			     "The receive buffer is too large\n");
@@ -610,14 +612,12 @@ static inline void process_cmdrequest(int recvlength, uint8_t *recvbuff,
 		return;
 	}
 
-	BUG_ON(!in_interrupt());
-
-	spin_lock(&priv->driver_lock);
+	spin_lock_irqsave(&priv->driver_lock, flags);
 	memcpy(priv->cmd_resp_buff, recvbuff + MESSAGE_HEADER_LEN,
 	       recvlength - MESSAGE_HEADER_LEN);
 	kfree_skb(skb);
 	lbtf_cmd_response_rx(priv);
-	spin_unlock(&priv->driver_lock);
+	spin_unlock_irqrestore(&priv->driver_lock, flags);
 }
 
 /**
-- 
2.17.1

Re: [2/4] libertas_tf: use irqsave() in USB's complete callback

[Kalle Valo]

Sebastian Andrzej Siewior <bigeasy@linutronix.de> wrote:

> The USB completion callback does not disable interrupts while acquiring
> the lock. We want to remove the local_irq_disable() invocation from
> __usb_hcd_giveback_urb() and therefore it is required for the callback
> handler to disable the interrupts while acquiring the lock.
> The callback may be invoked either in IRQ or BH context depending on the
> USB host controller.
> Use the _irqsave() variant of the locking primitives.
> 
> I am removing the
> 	BUG_ON(!in_interrupt());
> 
> check because it serves no purpose. Running the completion callback in
> BH context makes in_interrupt() still return true but the interrupts
> could be enabled. The important part is that ->driver_lock is acquired
> with disabled interrupts which is the case now.
> 
> Cc: Kalle Valo <kvalo@codeaurora.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: linux-wireless@vger.kernel.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

3 patches applied to wireless-drivers-next.git, thanks.

fc75122fabb5 libertas_tf: use irqsave() in USB's complete callback
a3128feef6d5 libertas: use irqsave() in USB's complete callback
81454b8405f2 zd1211rw: use irqsave() in USB's complete callback

-- 
https://patchwork.kernel.org/patch/10478609/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

[PATCH 4/4] zd1211rw: use irqsave() in USB's complete callback

[Sebastian Andrzej Siewior]

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

Cc: Daniel Drake <dsd@gentoo.org>
Cc: Ulrich Kunitz <kune@deine-taler.de>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/net/wireless/zydas/zd1211rw/zd_usb.c | 21 +++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireless/zydas/zd1211rw/zd_usb.c b/drivers/net/wireless/zydas/zd1211rw/zd_usb.c
index c30bf118c67d..c2cda3acd4af 100644
--- a/drivers/net/wireless/zydas/zd1211rw/zd_usb.c
+++ b/drivers/net/wireless/zydas/zd1211rw/zd_usb.c
@@ -371,25 +371,27 @@ static inline void handle_regs_int_override(struct urb *urb)
 {
 	struct zd_usb *usb = urb->context;
 	struct zd_usb_interrupt *intr = &usb->intr;
+	unsigned long flags;
 
-	spin_lock(&intr->lock);
+	spin_lock_irqsave(&intr->lock, flags);
 	if (atomic_read(&intr->read_regs_enabled)) {
 		atomic_set(&intr->read_regs_enabled, 0);
 		intr->read_regs_int_overridden = 1;
 		complete(&intr->read_regs.completion);
 	}
-	spin_unlock(&intr->lock);
+	spin_unlock_irqrestore(&intr->lock, flags);
 }
 
 static inline void handle_regs_int(struct urb *urb)
 {
 	struct zd_usb *usb = urb->context;
 	struct zd_usb_interrupt *intr = &usb->intr;
+	unsigned long flags;
 	int len;
 	u16 int_num;
 
 	ZD_ASSERT(in_interrupt());
-	spin_lock(&intr->lock);
+	spin_lock_irqsave(&intr->lock, flags);
 
 	int_num = le16_to_cpu(*(__le16 *)(urb->transfer_buffer+2));
 	if (int_num == CR_INTERRUPT) {
@@ -425,7 +427,7 @@ static inline void handle_regs_int(struct urb *urb)
 	}
 
 out:
-	spin_unlock(&intr->lock);
+	spin_unlock_irqrestore(&intr->lock, flags);
 
 	/* CR_INTERRUPT might override read_reg too. */
 	if (int_num == CR_INTERRUPT && atomic_read(&intr->read_regs_enabled))
@@ -665,6 +667,7 @@ static void rx_urb_complete(struct urb *urb)
 	struct zd_usb_rx *rx;
 	const u8 *buffer;
 	unsigned int length;
+	unsigned long flags;
 
 	switch (urb->status) {
 	case 0:
@@ -693,14 +696,14 @@ static void rx_urb_complete(struct urb *urb)
 		/* If there is an old first fragment, we don't care. */
 		dev_dbg_f(urb_dev(urb), "*** first fragment ***\n");
 		ZD_ASSERT(length <= ARRAY_SIZE(rx->fragment));
-		spin_lock(&rx->lock);
+		spin_lock_irqsave(&rx->lock, flags);
 		memcpy(rx->fragment, buffer, length);
 		rx->fragment_length = length;
-		spin_unlock(&rx->lock);
+		spin_unlock_irqrestore(&rx->lock, flags);
 		goto resubmit;
 	}
 
-	spin_lock(&rx->lock);
+	spin_lock_irqsave(&rx->lock, flags);
 	if (rx->fragment_length > 0) {
 		/* We are on a second fragment, we believe */
 		ZD_ASSERT(length + rx->fragment_length <=
@@ -710,9 +713,9 @@ static void rx_urb_complete(struct urb *urb)
 		handle_rx_packet(usb, rx->fragment,
 			         rx->fragment_length + length);
 		rx->fragment_length = 0;
-		spin_unlock(&rx->lock);
+		spin_unlock_irqrestore(&rx->lock, flags);
 	} else {
-		spin_unlock(&rx->lock);
+		spin_unlock_irqrestore(&rx->lock, flags);
 		handle_rx_packet(usb, buffer, length);
 	}
 
-- 
2.17.1