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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>
This commit is contained in:
Lukas Wunner 2018-07-19 17:27:39 -05:00 committed by Bjorn Helgaas
parent 7b4ce26bcf
commit ec07a44730
2 changed files with 34 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/pci/hotplug/pciehp.h
View File

@ -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;

67
drivers/pci/hotplug/pciehp_hpc.c
View File

@ -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;
}