From ec07a4473072ff0607e3126ce26c31dbf81f9a15 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Thu, 19 Jul 2018 17:27:39 -0500 Subject: [PATCH] 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 Signed-off-by: Bjorn Helgaas Cc: Thomas Gleixner --- drivers/pci/hotplug/pciehp.h | 4 +- drivers/pci/hotplug/pciehp_hpc.c | 67 +++++++++++++++----------------- 2 files changed, 34 insertions(+), 37 deletions(-) diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h index ab1d97a1822d..9f11360e3318 100644 --- 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 4ffaa3dfeb89..d36650f2d2bb 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -17,7 +17,7 @@ #include #include #include -#include +#include #include #include #include @@ -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; }