Use PCI hotplug lock to serialize hotplug operations triggered by the
pciehp driver.
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
---
drivers/pci/hotplug/pciehp.h | 2 +
drivers/pci/hotplug/pciehp_core.c | 7 ++++-
drivers/pci/hotplug/pciehp_ctrl.c | 48 +++++++++++++++++++++++++++++++++++++
drivers/pci/hotplug/pciehp_hpc.c | 1 +
4 files changed, 57 insertions(+), 1 deletions(-)
diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index c8a1a27..6078eea 100644
--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -117,6 +117,7 @@ struct controller {
#define BLINKINGOFF_STATE 2
#define POWERON_STATE 3
#define POWEROFF_STATE 4
+#define SHUTDOWN_STATE 5
#define ATTN_BUTTN(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_ABP)
#define POWER_CTRL(ctrl) ((ctrl)->slot_cap & PCI_EXP_SLTCAP_PCP)
@@ -160,6 +161,7 @@ void pciehp_green_led_off(struct slot *slot);
void pciehp_green_led_blink(struct slot *slot);
int pciehp_check_link_status(struct controller *ctrl);
void pciehp_release_ctrl(struct controller *ctrl);
+void pciehp_shutdown_slot(struct slot *slot);
static inline const char *slot_name(struct slot *slot)
{
diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 4ceefe3..2195f67 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -268,8 +268,11 @@ static int pciehp_probe(struct pcie_device *dev)
slot = ctrl->slot;
pciehp_get_adapter_status(slot, &occupied);
pciehp_get_power_status(slot, &poweron);
- if (occupied && pciehp_force)
+ if (occupied && pciehp_force) {
+ pci_hotplug_enter();
pciehp_enable_slot(slot);
+ pci_hotplug_exit();
+ }
/* If empty slot's power status is on, turn power off */
if (!occupied && poweron && POWER_CTRL(ctrl))
pciehp_power_off_slot(slot);
@@ -313,11 +316,13 @@ static int pciehp_resume (struct pcie_device *dev)
slot = ctrl->slot;
/* Check if slot is occupied */
+ pci_hotplug_enter();
pciehp_get_adapter_status(slot, &status);
if (status)
pciehp_enable_slot(slot);
else
pciehp_disable_slot(slot);
+ pci_hotplug_exit();
}
return 0;
}
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index 8f4d261..e859100 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -31,6 +31,7 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
+#include <linux/delay.h>
#include <linux/pci.h>
#include "../pci.h"
#include "pciehp.h"
@@ -290,6 +291,30 @@ static void pciehp_power_thread(struct work_struct *work)
struct power_work_info *info =
container_of(work, struct power_work_info, work);
struct slot *p_slot = info->p_slot;
+ bool shutdown;
+
+ /*
+ * Break out deadlock issues caused by following scenario:
+ * Thread A:
+ * 1) acquire the PCI hotplug lock
+ * 2) remove the PCI device associated with this PCIe HPC
+ * 3) call pciehp_remove() for this PCIe HPC
+ * 4) call flush_workqueue(pciehp_wq_power) to flush queued works
+ * 5) wait until all queued works have done
+ * Thread B is a workqueue worker thread:
+ * 1) call pciehp_power_thread() to handle hotplug requests
+ * 2) try to acquire the PCI hotplug lock
+ * Please refer to pciehp_shutdown_slot() for the counterpart.
+ */
+ while (!pci_hotplug_try_enter()) {
+ mutex_lock(&p_slot->lock);
+ shutdown = p_slot->state == SHUTDOWN_STATE;
+ mutex_unlock(&p_slot->lock);
+ if (shutdown)
+ goto out;
+ else
+ mdelay(1);
+ }
mutex_lock(&p_slot->lock);
switch (p_slot->state) {
@@ -315,6 +340,9 @@ static void pciehp_power_thread(struct work_struct *work)
}
mutex_unlock(&p_slot->lock);
+ pci_hotplug_exit();
+
+out:
kfree(info);
}
@@ -623,3 +651,23 @@ int pciehp_sysfs_disable_slot(struct slot *p_slot)
return retval;
}
+
+void pciehp_shutdown_slot(struct slot *slot)
+{
+ u8 getstatus;
+ struct controller *ctrl = slot->ctrl;
+
+ mutex_lock(&slot->lock);
+ slot->state = SHUTDOWN_STATE;
+ mutex_unlock(&slot->lock);
+
+ if (ATTN_LED(ctrl))
+ pciehp_set_attention_status(slot, 0);
+ if (PWR_LED(ctrl)) {
+ pciehp_get_power_status(slot, &getstatus);
+ if (getstatus)
+ pciehp_green_led_on(slot);
+ else
+ pciehp_green_led_off(slot);
+ }
+}
diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index d5c826d..c492b2c 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -902,6 +902,7 @@ static void pcie_cleanup_slot(struct controller *ctrl)
*/
flush_workqueue(pciehp_wq_event);
cancel_delayed_work_sync(&slot->work);
+ pciehp_shutdown_slot(slot);
flush_workqueue(pciehp_wq_power);
kfree(slot);
--
1.7.5.4
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