Merge branch 'pci/hotplug'

- Ignore Presence Detect Changed caused by DPC.  pciehp already ignores
  Link Down/Up events caused by DPC, but on slots using in-band presence
  detect, DPC causes a spurious Presence Detect Changed event (Lukas
  Wunner)

- Ignore Link Down/Up caused by Secondary Bus Reset.  On hotplug ports
  using in-band presence detect, the reset causes a Presence Detect Changed
  event, which mistakenly caused teardown and re-enumeration of the device.
  Drivers may need to annotate code that resets their device (Lukas Wunner)

* pci/hotplug:
  PCI: hotplug: Drop superfluous #include directives
  PCI: pciehp: Ignore Link Down/Up caused by Secondary Bus Reset
  PCI: pciehp: Ignore Presence Detect Changed caused by DPC

# Conflicts:
#	drivers/pci/pci.h

Author: bjorn-helgaas

drivers/pci/hotplug/pci_hotplug_core.c

@@ -20,13 +20,9 @@
 #include <linux/types.h>
 #include <linux/kobject.h>
 #include <linux/sysfs.h>
-#include <linux/pagemap.h>
 #include <linux/init.h>
-#include <linux/mount.h>
-#include <linux/namei.h>
 #include <linux/pci.h>
 #include <linux/pci_hotplug.h>
-#include <linux/uaccess.h>
 #include "../pci.h"
 #include "cpci_hotplug.h"
 
@@ -492,6 +488,75 @@ void pci_hp_destroy(struct hotplug_slot *slot)
 }
 EXPORT_SYMBOL_GPL(pci_hp_destroy);
 
+static DECLARE_WAIT_QUEUE_HEAD(pci_hp_link_change_wq);
+
+/**
+ * pci_hp_ignore_link_change - begin code section causing spurious link changes
+ * @pdev: PCI hotplug bridge
+ *
+ * Mark the beginning of a code section causing spurious link changes on the
+ * Secondary Bus of @pdev, e.g. as a side effect of a Secondary Bus Reset,
+ * D3cold transition, firmware update or FPGA reconfiguration.
+ *
+ * Hotplug drivers can thus check whether such a code section is executing
+ * concurrently, await it with pci_hp_spurious_link_change() and ignore the
+ * resulting link change events.
+ *
+ * Must be paired with pci_hp_unignore_link_change().  May be called both
+ * from the PCI core and from Endpoint drivers.  May be called for bridges
+ * which are not hotplug-capable, in which case it has no effect because
+ * no hotplug driver is bound to the bridge.
+ */
+void pci_hp_ignore_link_change(struct pci_dev *pdev)
+{
+	set_bit(PCI_LINK_CHANGING, &pdev->priv_flags);
+	smp_mb__after_atomic(); /* pairs with implied barrier of wait_event() */
+}
+
+/**
+ * pci_hp_unignore_link_change - end code section causing spurious link changes
+ * @pdev: PCI hotplug bridge
+ *
+ * Mark the end of a code section causing spurious link changes on the
+ * Secondary Bus of @pdev.  Must be paired with pci_hp_ignore_link_change().
+ */
+void pci_hp_unignore_link_change(struct pci_dev *pdev)
+{
+	set_bit(PCI_LINK_CHANGED, &pdev->priv_flags);
+	mb(); /* ensure pci_hp_spurious_link_change() sees either bit set */
+	clear_bit(PCI_LINK_CHANGING, &pdev->priv_flags);
+	wake_up_all(&pci_hp_link_change_wq);
+}
+
+/**
+ * pci_hp_spurious_link_change - check for spurious link changes
+ * @pdev: PCI hotplug bridge
+ *
+ * Check whether a code section is executing concurrently which is causing
+ * spurious link changes on the Secondary Bus of @pdev.  Await the end of the
+ * code section if so.
+ *
+ * May be called by hotplug drivers to check whether a link change is spurious
+ * and can be ignored.
+ *
+ * Because a genuine link change may have occurred in-between a spurious link
+ * change and the invocation of this function, hotplug drivers should perform
+ * sanity checks such as retrieving the current link state and bringing down
+ * the slot if the link is down.
+ *
+ * Return: %true if such a code section has been executing concurrently,
+ * otherwise %false.  Also return %true if such a code section has not been
+ * executing concurrently, but at least once since the last invocation of this
+ * function.
+ */
+bool pci_hp_spurious_link_change(struct pci_dev *pdev)
+{
+	wait_event(pci_hp_link_change_wq,
+		   !test_bit(PCI_LINK_CHANGING, &pdev->priv_flags));
+
+	return test_and_clear_bit(PCI_LINK_CHANGED, &pdev->priv_flags);
+}
+
 static int __init pci_hotplug_init(void)
 {
 	int result;

drivers/pci/hotplug/pciehp.h

@@ -187,6 +187,7 @@ int pciehp_card_present(struct controller *ctrl);
 int pciehp_card_present_or_link_active(struct controller *ctrl);
 int pciehp_check_link_status(struct controller *ctrl);
 int pciehp_check_link_active(struct controller *ctrl);
+bool pciehp_device_replaced(struct controller *ctrl);
 void pciehp_release_ctrl(struct controller *ctrl);
 
 int pciehp_sysfs_enable_slot(struct hotplug_slot *hotplug_slot);

drivers/pci/hotplug/pciehp_core.c

@@ -284,35 +284,6 @@ static int pciehp_suspend(struct pcie_device *dev)
 	return 0;
 }
 
-static bool pciehp_device_replaced(struct controller *ctrl)
-{
-	struct pci_dev *pdev __free(pci_dev_put) = NULL;
-	u32 reg;
-
-	if (pci_dev_is_disconnected(ctrl->pcie->port))
-		return false;
-
-	pdev = pci_get_slot(ctrl->pcie->port->subordinate, PCI_DEVFN(0, 0));
-	if (!pdev)
-		return true;
-
-	if (pci_read_config_dword(pdev, PCI_VENDOR_ID, &reg) ||
-	    reg != (pdev->vendor | (pdev->device << 16)) ||
-	    pci_read_config_dword(pdev, PCI_CLASS_REVISION, &reg) ||
-	    reg != (pdev->revision | (pdev->class << 8)))
-		return true;
-
-	if (pdev->hdr_type == PCI_HEADER_TYPE_NORMAL &&
-	    (pci_read_config_dword(pdev, PCI_SUBSYSTEM_VENDOR_ID, &reg) ||
-	     reg != (pdev->subsystem_vendor | (pdev->subsystem_device << 16))))
-		return true;
-
-	if (pci_get_dsn(pdev) != ctrl->dsn)
-		return true;
-
-	return false;
-}
-
 static int pciehp_resume_noirq(struct pcie_device *dev)
 {
 	struct controller *ctrl = get_service_data(dev);

drivers/pci/hotplug/pciehp_hpc.c

@@ -563,29 +563,59 @@ void pciehp_power_off_slot(struct controller *ctrl)
 		 PCI_EXP_SLTCTL_PWR_OFF);
 }
 
-static void pciehp_ignore_dpc_link_change(struct controller *ctrl,
-					  struct pci_dev *pdev, int irq)
+bool pciehp_device_replaced(struct controller *ctrl)
+{
+	struct pci_dev *pdev __free(pci_dev_put) = NULL;
+	u32 reg;
+
+	if (pci_dev_is_disconnected(ctrl->pcie->port))
+		return false;
+
+	pdev = pci_get_slot(ctrl->pcie->port->subordinate, PCI_DEVFN(0, 0));
+	if (!pdev)
+		return true;
+
+	if (pci_read_config_dword(pdev, PCI_VENDOR_ID, &reg) ||
+	    reg != (pdev->vendor | (pdev->device << 16)) ||
+	    pci_read_config_dword(pdev, PCI_CLASS_REVISION, &reg) ||
+	    reg != (pdev->revision | (pdev->class << 8)))
+		return true;
+
+	if (pdev->hdr_type == PCI_HEADER_TYPE_NORMAL &&
+	    (pci_read_config_dword(pdev, PCI_SUBSYSTEM_VENDOR_ID, &reg) ||
+	     reg != (pdev->subsystem_vendor | (pdev->subsystem_device << 16))))
+		return true;
+
+	if (pci_get_dsn(pdev) != ctrl->dsn)
+		return true;
+
+	return false;
+}
+
+static void pciehp_ignore_link_change(struct controller *ctrl,
+				      struct pci_dev *pdev, int irq,
+				      u16 ignored_events)
 {
 	/*
 	 * Ignore link changes which occurred while waiting for DPC recovery.
 	 * Could be several if DPC triggered multiple times consecutively.
+	 * Also ignore link changes caused by Secondary Bus Reset, etc.
 	 */
 	synchronize_hardirq(irq);
-	atomic_and(~PCI_EXP_SLTSTA_DLLSC, &ctrl->pending_events);
+	atomic_and(~ignored_events, &ctrl->pending_events);
 	if (pciehp_poll_mode)
 		pcie_capability_write_word(pdev, PCI_EXP_SLTSTA,
-					   PCI_EXP_SLTSTA_DLLSC);
-	ctrl_info(ctrl, "Slot(%s): Link Down/Up ignored (recovered by DPC)\n",
-		  slot_name(ctrl));
+					   ignored_events);
+	ctrl_info(ctrl, "Slot(%s): Link Down/Up ignored\n", slot_name(ctrl));
 
 	/*
 	 * If the link is unexpectedly down after successful recovery,
 	 * the corresponding link change may have been ignored above.
 	 * Synthesize it to ensure that it is acted on.
 	 */
 	down_read_nested(&ctrl->reset_lock, ctrl->depth);
-	if (!pciehp_check_link_active(ctrl))
-		pciehp_request(ctrl, PCI_EXP_SLTSTA_DLLSC);
+	if (!pciehp_check_link_active(ctrl) || pciehp_device_replaced(ctrl))
+		pciehp_request(ctrl, ignored_events);
 	up_read(&ctrl->reset_lock);
 }
 
@@ -732,12 +762,19 @@ static irqreturn_t pciehp_ist(int irq, void *dev_id)
 
 	/*
 	 * Ignore Link Down/Up events caused by Downstream Port Containment
-	 * if recovery from the error succeeded.
+	 * if recovery succeeded, or caused by Secondary Bus Reset,
+	 * suspend to D3cold, firmware update, FPGA reconfiguration, etc.
 	 */
-	if ((events & PCI_EXP_SLTSTA_DLLSC) && pci_dpc_recovered(pdev) &&
+	if ((events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC)) &&
+	    (pci_dpc_recovered(pdev) || pci_hp_spurious_link_change(pdev)) &&
 	    ctrl->state == ON_STATE) {
-		events &= ~PCI_EXP_SLTSTA_DLLSC;
-		pciehp_ignore_dpc_link_change(ctrl, pdev, irq);
+		u16 ignored_events = PCI_EXP_SLTSTA_DLLSC;
+
+		if (!ctrl->inband_presence_disabled)
+			ignored_events |= events & PCI_EXP_SLTSTA_PDC;
+
+		events &= ~ignored_events;
+		pciehp_ignore_link_change(ctrl, pdev, irq, ignored_events);
 	}
 
 	/*
@@ -902,31 +939,18 @@ int pciehp_reset_slot(struct hotplug_slot *hotplug_slot, bool probe)
 {
 	struct controller *ctrl = to_ctrl(hotplug_slot);
 	struct pci_dev *pdev = ctrl_dev(ctrl);
-	u16 stat_mask = 0, ctrl_mask = 0;
 	int rc;
 
 	if (probe)
 		return 0;
 
 	down_write_nested(&ctrl->reset_lock, ctrl->depth);
 
-	if (!ATTN_BUTTN(ctrl)) {
-		ctrl_mask |= PCI_EXP_SLTCTL_PDCE;
-		stat_mask |= PCI_EXP_SLTSTA_PDC;
-	}
-	ctrl_mask |= PCI_EXP_SLTCTL_DLLSCE;
-	stat_mask |= PCI_EXP_SLTSTA_DLLSC;
-
-	pcie_write_cmd(ctrl, 0, ctrl_mask);
-	ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
-		 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, 0);
+	pci_hp_ignore_link_change(pdev);
 
 	rc = pci_bridge_secondary_bus_reset(ctrl->pcie->port);
 
-	pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, stat_mask);
-	pcie_write_cmd_nowait(ctrl, ctrl_mask, ctrl_mask);
-	ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
-		 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, ctrl_mask);
+	pci_hp_unignore_link_change(pdev);
 
 	up_write(&ctrl->reset_lock);
 	return rc;

drivers/pci/pci.h

@@ -227,6 +227,7 @@ static inline int pci_proc_detach_bus(struct pci_bus *bus) { return 0; }
 
 /* Functions for PCI Hotplug drivers to use */
 int pci_hp_add_bridge(struct pci_dev *dev);
+bool pci_hp_spurious_link_change(struct pci_dev *pdev);
 
 #if defined(CONFIG_SYSFS) && defined(HAVE_PCI_LEGACY)
 void pci_create_legacy_files(struct pci_bus *bus);
@@ -557,6 +558,8 @@ static inline int pci_dev_set_disconnected(struct pci_dev *dev, void *unused)
 #define PCI_DPC_RECOVERED 1
 #define PCI_DPC_RECOVERING 2
 #define PCI_DEV_REMOVED 3
+#define PCI_LINK_CHANGED 4
+#define PCI_LINK_CHANGING 5
 #define PCI_LINK_LBMS_SEEN	6
 #define PCI_DEV_ALLOW_BINDING 7
 

include/linux/pci.h

@@ -1843,6 +1843,14 @@ static inline bool pcie_aspm_support_enabled(void) { return false; }
 static inline bool pcie_aspm_enabled(struct pci_dev *pdev) { return false; }
 #endif
 
+#ifdef CONFIG_HOTPLUG_PCI
+void pci_hp_ignore_link_change(struct pci_dev *pdev);
+void pci_hp_unignore_link_change(struct pci_dev *pdev);
+#else
+static inline void pci_hp_ignore_link_change(struct pci_dev *pdev) { }
+static inline void pci_hp_unignore_link_change(struct pci_dev *pdev) { }
+#endif
+
 #ifdef CONFIG_PCIEAER
 bool pci_aer_available(void);
 #else