[PATCH RFC 3/6] net: phy: Threaded interrupts allow some simplification

The PHY interrupts are now handled in a threaded interrupt handler,
which can sleep. The work queue is no longer needed, phy_change() can
be called directly. Additionally, none of the callers of
phy_mac_interrupt() did so in interrupt context, so fully remove the
work queue, and document that phy_mac_interrupt() should not be called
in interrupt context.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/net/phy/phy.c        | 37 ++++++++++++++++---------------------
 drivers/net/phy/phy_device.c |  1 -
 include/linux/phy.h          |  4 +---
 3 files changed, 17 insertions(+), 25 deletions(-)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 5c29ed72f721..09fa8a950af1 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c

@@ -647,7 +647,7 @@ static void phy_error(struct phy_device *phydev)
  * @phy_dat: phy_device pointer
  *
  * Description: When a PHY interrupt occurs, the handler disables
- * interrupts, and schedules a work task to clear the interrupt.
+ * interrupts, and uses phy_change to handle the interrupt.
  */
 static irqreturn_t phy_interrupt(int irq, void *phy_dat)
 {

@@ -656,15 +656,10 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat)
 	if (PHY_HALTED == phydev->state)
 		return IRQ_NONE;		/* It can't be ours.  */
 
-	/* The MDIO bus is not allowed to be written in interrupt
-	 * context, so we need to disable the irq here.  A work
-	 * queue will write the PHY to disable and clear the
-	 * interrupt, and then reenable the irq line.
-	 */
 	disable_irq_nosync(irq);
 	atomic_inc(&phydev->irq_disable);
 
-	queue_work(system_power_efficient_wq, &phydev->phy_queue);
+	phy_change(phydev);
 
 	return IRQ_HANDLED;
 }

@@ -748,12 +743,6 @@ int phy_stop_interrupts(struct phy_device *phydev)
 
 	free_irq(phydev->irq, phydev);
 
-	/* Cannot call flush_scheduled_work() here as desired because
-	 * of rtnl_lock(), but we do not really care about what would
-	 * be done, except from enable_irq(), so cancel any work
-	 * possibly pending and take care of the matter below.
-	 */
-	cancel_work_sync(&phydev->phy_queue);
 	/* If work indeed has been cancelled, disable_irq() will have
 	 * been left unbalanced from phy_interrupt() and enable_irq()
 	 * has to be called so that other devices on the line work.

@@ -766,14 +755,11 @@ int phy_stop_interrupts(struct phy_device *phydev)
 EXPORT_SYMBOL(phy_stop_interrupts);
 
 /**
- * phy_change - Scheduled by the phy_interrupt/timer to handle PHY changes
- * @work: work_struct that describes the work to be done
+ * phy_change - Called by the phy_interrupt to handle PHY changes
+ * @phydev: phy_device struct that interrupted
  */
-void phy_change(struct work_struct *work)
+void phy_change(struct phy_device *phydev)
 {
-	struct phy_device *phydev =
-		container_of(work, struct phy_device, phy_queue);
-
 	if (phy_interrupt_is_valid(phydev)) {
 		if (phydev->drv->did_interrupt &&
 		    !phydev->drv->did_interrupt(phydev))

@@ -1097,12 +1083,21 @@ void phy_state_machine(struct work_struct *work)
 				   PHY_STATE_TIME * HZ);
 }
 
+/**
+ * phy_mac_interrupt - MAC says the link has changed
+ * @phydev: phy_device struct with changed link
+ * @new_link: Link is Up/Down.
+ *
+ * Description: The MAC layer is able indicate there has been a change
+ *   in the PHY link status. Set the new link status, and trigger the
+ *   state machine if needed.
+ *   Cannot be called in Interrupt context.
+ */
 void phy_mac_interrupt(struct phy_device *phydev, int new_link)
 {
 	phydev->link = new_link;
 
-	/* Trigger a state machine change */
-	queue_work(system_power_efficient_wq, &phydev->phy_queue);
+	phy_change(phydev);
 }
 EXPORT_SYMBOL(phy_mac_interrupt);
 

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index e977ba931878..bae4452700ab 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c

@@ -347,7 +347,6 @@ struct phy_device *phy_device_create(struct mii_bus *bus, int addr, int phy_id,
 
 	mutex_init(&dev->lock);
 	INIT_DELAYED_WORK(&dev->state_queue, phy_state_machine);
-	INIT_WORK(&dev->phy_queue, phy_change);
 
 	/* Request the appropriate module unconditionally; don't
 	 * bother trying to do so only if it isn't already loaded,

diff --git a/include/linux/phy.h b/include/linux/phy.h
index e25f1830fbcf..692e3e5a8a7c 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h

@@ -343,7 +343,6 @@ struct phy_c45_device_ids {
  * giving up on the current attempt at acquiring a link
  * irq: IRQ number of the PHY's interrupt (-1 if none)
  * phy_timer: The timer for handling the state machine
- * phy_queue: A work_queue for the interrupt
  * attached_dev: The attached enet driver's device instance ptr
  * adjust_link: Callback for the enet controller to respond to
  * changes in the link state.

@@ -416,7 +415,6 @@ struct phy_device {
 	void *priv;
 
 	/* Interrupt and Polling infrastructure */
-	struct work_struct phy_queue;
 	struct delayed_work state_queue;
 	atomic_t irq_disable;
 

@@ -802,7 +800,7 @@ int phy_driver_register(struct phy_driver *new_driver, struct module *owner);
 int phy_drivers_register(struct phy_driver *new_driver, int n,
 			 struct module *owner);
 void phy_state_machine(struct work_struct *work);
-void phy_change(struct work_struct *work);
+void phy_change(struct phy_device *phydev);
 void phy_mac_interrupt(struct phy_device *phydev, int new_link);
 void phy_start_machine(struct phy_device *phydev);
 void phy_stop_machine(struct phy_device *phydev);

-- 
2.9.3

Hello.

On 9/28/2016 11:32 AM, Andrew Lunn wrote:

The PHY interrupts are now handled in a threaded interrupt handler,
which can sleep. The work queue is no longer needed, phy_change() can
be called directly. Additionally, none of the callers of
phy_mac_interrupt() did so in interrupt context, so fully remove the

   I did intend to call it from interrupt context (from the ravb driver).

work queue, and document that phy_mac_interrupt() should not be called
in interrupt context.

   It was intentionally made callable from the interrupt context, I'd prefer if you wouldn't change that.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>

[...]

MBR, Sergei

On 9/28/2016 2:46 PM, Sergei Shtylyov wrote:

quoted

The PHY interrupts are now handled in a threaded interrupt handler,
which can sleep. The work queue is no longer needed, phy_change() can
be called directly. Additionally, none of the callers of
phy_mac_interrupt() did so in interrupt context, so fully remove the

   I did intend to call it from interrupt context (from the ravb driver).

quoted

work queue, and document that phy_mac_interrupt() should not be called
in interrupt context.

   It was intentionally made callable from the interrupt context, I'd prefer
if you wouldn't change that.

   OTOH, it's still not very handy to call because of the 'new_link' parameter which I'm not sure I can provide...

quoted

Signed-off-by: Andrew Lunn <andrew@lunn.ch>

[...]

MBR, Sergei

On Wed, Sep 28, 2016 at 03:13:46PM +0300, Sergei Shtylyov wrote:

On 9/28/2016 2:46 PM, Sergei Shtylyov wrote:

quoted

quoted

The PHY interrupts are now handled in a threaded interrupt handler,
which can sleep. The work queue is no longer needed, phy_change() can
be called directly. Additionally, none of the callers of
phy_mac_interrupt() did so in interrupt context, so fully remove the

  I did intend to call it from interrupt context (from the ravb driver).

quoted

work queue, and document that phy_mac_interrupt() should not be called
in interrupt context.

  It was intentionally made callable from the interrupt context, I'd prefer
if you wouldn't change that.

   OTOH, it's still not very handy to call because of the 'new_link'
parameter which I'm not sure I can provide...

Hi Sergei

If there is a need for it, i will leave the work queue and keep this
code unchanged.

   Andrew

On 09/28/2016 03:28 PM, Andrew Lunn wrote:

quoted

quoted

quoted

The PHY interrupts are now handled in a threaded interrupt handler,
which can sleep. The work queue is no longer needed, phy_change() can
be called directly. Additionally, none of the callers of
phy_mac_interrupt() did so in interrupt context, so fully remove the

  I did intend to call it from interrupt context (from the ravb driver).

quoted

work queue, and document that phy_mac_interrupt() should not be called
in interrupt context.

  It was intentionally made callable from the interrupt context, I'd prefer
if you wouldn't change that.

   OTOH, it's still not very handy to call because of the 'new_link'
parameter which I'm not sure I can provide...

Hi Sergei

If there is a need for it, i will leave the work queue and keep this
code unchanged.

   Let's hear what Florian says...

   Andrew

MBR, Sergei

On 09/28/2016 06:38 AM, Sergei Shtylyov wrote:

On 09/28/2016 03:28 PM, Andrew Lunn wrote:

quoted

quoted

quoted

quoted

The PHY interrupts are now handled in a threaded interrupt handler,
which can sleep. The work queue is no longer needed, phy_change() can
be called directly. Additionally, none of the callers of
phy_mac_interrupt() did so in interrupt context, so fully remove the

  I did intend to call it from interrupt context (from the ravb
driver).

quoted

work queue, and document that phy_mac_interrupt() should not be called
in interrupt context.

  It was intentionally made callable from the interrupt context, I'd
prefer
if you wouldn't change that.

   OTOH, it's still not very handy to call because of the 'new_link'
parameter which I'm not sure I can provide...

Hi Sergei

If there is a need for it, i will leave the work queue and keep this
code unchanged.

   Let's hear what Florian says...

The intent is really to have phy_mac_interrupt() callable from hard IRQ
context, not that this matters really too much because link events
already occur in the slow path, but it's nice to have that property
retained IMHO.
-- 
Florian

Hello!

On 9/28/2016 8:14 PM, Florian Fainelli wrote:

quoted

quoted

quoted

quoted

quoted

The PHY interrupts are now handled in a threaded interrupt handler,
which can sleep. The work queue is no longer needed, phy_change() can
be called directly. Additionally, none of the callers of
phy_mac_interrupt() did so in interrupt context, so fully remove the

  I did intend to call it from interrupt context (from the ravb
driver).

quoted

work queue, and document that phy_mac_interrupt() should not be called
in interrupt context.

  It was intentionally made callable from the interrupt context, I'd
prefer
if you wouldn't change that.

   OTOH, it's still not very handy to call because of the 'new_link'
parameter which I'm not sure I can provide...

Hi Sergei

If there is a need for it, i will leave the work queue and keep this
code unchanged.

   Let's hear what Florian says...

The intent is really to have phy_mac_interrupt() callable from hard IRQ
context, not that this matters really too much because link events
already occur in the slow path, but it's nice to have that property
retained IMHO.

   Actually, I still don't know how to call phy_mac_interrupt() from the ravb driver because of the 'new_link' parameter -- I won't always have that signal connected to the MAC...

MBR, Sergei

   Actually, I still don't know how to call phy_mac_interrupt() from
the ravb driver because of the 'new_link' parameter -- I won't
always have that signal connected to the MAC...

I'm not sure that parameter is of any use. I really think the
semantics of this call should be, something has changed, go and ask
the PHY driver to find out what. Just the same as if the PHY had
triggered an interrupt.

	  Andrew