Commit ec07a447 authored by Lukas Wunner's avatar Lukas Wunner Committed by Bjorn Helgaas
Browse files

PCI: pciehp: Convert to threaded polling 



We've just converted pciehp to threaded IRQ handling, but still cannot
sleep in pciehp_ist() because the function is also called in poll mode,
which runs in softirq context (from a timer).

Convert poll mode to a kthread so that pciehp_ist() always runs in task
context.

Signed-off-by: default avatarLukas Wunner <lukas@wunner.de>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
parent 7b4ce26b

drivers/pci/hotplug/pciehp.h

+2 −2
Original line number Diff line number Diff line
@@ -97,7 +97,7 @@ struct event_info { 
 *	used for synchronous writes to the Slot Control register

 * @slot_cap: cached copy of the Slot Capabilities register

 * @slot_ctrl: cached copy of the Slot Control register

 * @poll_timer: timer to poll for slot events if no IRQ is available,

 * @poll_thread: thread to poll for slot events if no IRQ is available,

 *	enabled with pciehp_poll_mode module parameter

 * @cmd_started: jiffies when the Slot Control register was last written;

 *	the next write is allowed 1 second later, absent a Command Completed
@@ -122,7 +122,7 @@ struct controller { 
	wait_queue_head_t queue;

	u32 slot_cap;

	u16 slot_ctrl;

	struct timer_list poll_timer;

	struct task_struct *poll_thread;

	unsigned long cmd_started;	/* jiffies */

	unsigned int cmd_busy:1;

	unsigned int link_active_reporting:1;

drivers/pci/hotplug/pciehp_hpc.c

+32 −35
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ 
#include <linux/types.h>

#include <linux/signal.h>

#include <linux/jiffies.h>

#include <linux/timer.h>

#include <linux/kthread.h>

#include <linux/pci.h>

#include <linux/interrupt.h>

#include <linux/time.h>
@@ -33,43 +33,17 @@ static inline struct pci_dev *ctrl_dev(struct controller *ctrl) 


static irqreturn_t pciehp_isr(int irq, void *dev_id);

static irqreturn_t pciehp_ist(int irq, void *dev_id);

static void start_int_poll_timer(struct controller *ctrl, int sec);



/* This is the interrupt polling timeout function. */

static void int_poll_timeout(struct timer_list *t)

{

	struct controller *ctrl = from_timer(ctrl, t, poll_timer);



	/* Poll for interrupt events.  regs == NULL => polling */

	while (pciehp_isr(IRQ_NOTCONNECTED, ctrl) == IRQ_WAKE_THREAD)

		pciehp_ist(IRQ_NOTCONNECTED, ctrl);



	if (!pciehp_poll_time)

		pciehp_poll_time = 2; /* default polling interval is 2 sec */



	start_int_poll_timer(ctrl, pciehp_poll_time);

}



/* This function starts the interrupt polling timer. */

static void start_int_poll_timer(struct controller *ctrl, int sec)

{

	/* Clamp to sane value */

	if ((sec <= 0) || (sec > 60))

		sec = 2;



	ctrl->poll_timer.expires = jiffies + sec * HZ;

	add_timer(&ctrl->poll_timer);

}

static int pciehp_poll(void *data);



static inline int pciehp_request_irq(struct controller *ctrl)

{

	int retval, irq = ctrl->pcie->irq;



	/* Install interrupt polling timer. Start with 10 sec delay */

	if (pciehp_poll_mode) {

		timer_setup(&ctrl->poll_timer, int_poll_timeout, 0);

		start_int_poll_timer(ctrl, 10);

		return 0;

		ctrl->poll_thread = kthread_run(&pciehp_poll, ctrl,

						"pciehp_poll-%s",

						slot_name(ctrl->slot));

		return PTR_ERR_OR_ZERO(ctrl->poll_thread);

	}



	/* Installs the interrupt handler */
@@ -84,7 +58,7 @@ static inline int pciehp_request_irq(struct controller *ctrl) 
static inline void pciehp_free_irq(struct controller *ctrl)

{

	if (pciehp_poll_mode)

		del_timer_sync(&ctrl->poll_timer);

		kthread_stop(ctrl->poll_thread);

	else

		free_irq(ctrl->pcie->irq, ctrl);

}
@@ -652,6 +626,29 @@ static irqreturn_t pciehp_ist(int irq, void *dev_id) 
	return IRQ_HANDLED;

}



static int pciehp_poll(void *data)

{

	struct controller *ctrl = data;



	schedule_timeout_idle(10 * HZ); /* start with 10 sec delay */



	while (!kthread_should_stop()) {

		if (kthread_should_park())

			kthread_parkme();



		/* poll for interrupt events */

		while (pciehp_isr(IRQ_NOTCONNECTED, ctrl) == IRQ_WAKE_THREAD)

			pciehp_ist(IRQ_NOTCONNECTED, ctrl);



		if (pciehp_poll_time <= 0 || pciehp_poll_time > 60)

			pciehp_poll_time = 2; /* clamp to sane value */



		schedule_timeout_idle(pciehp_poll_time * HZ);

	}



	return 0;

}



static void pcie_enable_notification(struct controller *ctrl)

{

	u16 cmd, mask;
@@ -742,7 +739,7 @@ int pciehp_reset_slot(struct slot *slot, int probe) 
	ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,

		 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, 0);

	if (pciehp_poll_mode)

		del_timer_sync(&ctrl->poll_timer);

		kthread_park(ctrl->poll_thread);



	pci_reset_bridge_secondary_bus(ctrl->pcie->port);
@@ -751,7 +748,7 @@ int pciehp_reset_slot(struct slot *slot, int probe) 
	ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,

		 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, ctrl_mask);

	if (pciehp_poll_mode)

		int_poll_timeout(&ctrl->poll_timer);

		kthread_unpark(ctrl->poll_thread);

	return 0;

}

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