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: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>

diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index ab1d97a1822d71c76eb291d8c2f89f6e75a32573..9f11360e331848251cb8acee1a4078e619ceaf9a 100644 (file)
--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -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;

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 4ffaa3dfeb89b84b31dfa3de5900065b86fdc414..d36650f2d2bb75baa9b5df799dc8bb80bdc81168 100644 (file)
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -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;
 }