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[PATCH 1/5] PCI: protect restore with device lock to be consistent

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  [PATCH 1/5] PCI: protect restore with device lock to be consistent Sinan Kaya <okaya@codeaurora.org> - 2017-09-24 02:20 +0200
    [PATCH 2/5] PCI: handle FLR failure and allow other reset types Sinan Kaya <okaya@codeaurora.org> - 2017-09-24 02:20 +0200
    [PATCH 4/5] PCI: wait device ready after pci_pm_reset() Sinan Kaya <okaya@codeaurora.org> - 2017-09-24 02:20 +0200

#1738091 — [PATCH 1/5] PCI: protect restore with device lock to be consistent

Commit b014e96d1abb ("PCI: Protect pci_error_handlers->reset_notify() usage
with device_lock()") added protection around pci_dev_restore() function so
that device specific remove callback does not cause a race condition
against hotplug.

pci_dev_lock() usage has been forgotten in two different places in the
code. Adding locks for pci_slot_restore() and moving pci_dev_restore()
inside the locks for pci_try_reset_function().

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/pci/pci.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6078dfc..23681f4 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4344,9 +4344,9 @@ int pci_try_reset_function(struct pci_dev *dev)
 
 	pci_dev_save_and_disable(dev);
 	rc = __pci_reset_function_locked(dev);
+	pci_dev_restore(dev);
 	pci_dev_unlock(dev);
 
-	pci_dev_restore(dev);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(pci_try_reset_function);
@@ -4546,7 +4546,9 @@ static void pci_slot_restore(struct pci_slot *slot)
 	list_for_each_entry(dev, &slot->bus->devices, bus_list) {
 		if (!dev->slot || dev->slot != slot)
 			continue;
+		pci_dev_lock(dev);
 		pci_dev_restore(dev);
+		pci_dev_unlock(dev);
 		if (dev->subordinate)
 			pci_bus_restore(dev->subordinate);
 	}
-- 
1.9.1

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#1738093 — [PATCH 2/5] PCI: handle FLR failure and allow other reset types

pci_flr_wait() and pci_af_flr() functions assume graceful return even
though the device is inaccessible under error conditions.

Return -ENOTTY in error cases so that __pci_reset_function_locked() can
try other reset types if AF_FLR/FLR reset fails.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/pci/pci.c   | 18 ++++++++++--------
 include/linux/pci.h |  2 +-
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 23681f4..27ec45d 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3820,7 +3820,7 @@ int pci_wait_for_pending_transaction(struct pci_dev *dev)
 }
 EXPORT_SYMBOL(pci_wait_for_pending_transaction);
 
-static void pci_flr_wait(struct pci_dev *dev)
+static int pci_flr_wait(struct pci_dev *dev)
 {
 	int delay = 1, timeout = 60000;
 	u32 id;
@@ -3849,7 +3849,7 @@ static void pci_flr_wait(struct pci_dev *dev)
 		if (delay > timeout) {
 			dev_warn(&dev->dev, "not ready %dms after FLR; giving up\n",
 				 100 + delay - 1);
-			return;
+			return -ENOTTY;
 		}
 
 		if (delay > 1000)
@@ -3863,6 +3863,8 @@ static void pci_flr_wait(struct pci_dev *dev)
 
 	if (delay > 1000)
 		dev_info(&dev->dev, "ready %dms after FLR\n", 100 + delay - 1);
+
+	return 0;
 }
 
 /**
@@ -3891,13 +3893,13 @@ static bool pcie_has_flr(struct pci_dev *dev)
  * device supports FLR before calling this function, e.g. by using the
  * pcie_has_flr() helper.
  */
-void pcie_flr(struct pci_dev *dev)
+int pcie_flr(struct pci_dev *dev)
 {
 	if (!pci_wait_for_pending_transaction(dev))
 		dev_err(&dev->dev, "timed out waiting for pending transaction; performing function level reset anyway\n");
 
 	pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_BCR_FLR);
-	pci_flr_wait(dev);
+	return pci_flr_wait(dev);
 }
 EXPORT_SYMBOL_GPL(pcie_flr);
 
@@ -3930,8 +3932,7 @@ static int pci_af_flr(struct pci_dev *dev, int probe)
 		dev_err(&dev->dev, "timed out waiting for pending transaction; performing AF function level reset anyway\n");
 
 	pci_write_config_byte(dev, pos + PCI_AF_CTRL, PCI_AF_CTRL_FLR);
-	pci_flr_wait(dev);
-	return 0;
+	return pci_flr_wait(dev);
 }
 
 /**
@@ -4203,8 +4204,9 @@ int __pci_reset_function_locked(struct pci_dev *dev)
 	if (rc != -ENOTTY)
 		return rc;
 	if (pcie_has_flr(dev)) {
-		pcie_flr(dev);
-		return 0;
+		rc = pcie_flr(dev);
+		if (rc != -ENOTTY)
+			return rc;
 	}
 	rc = pci_af_flr(dev, 0);
 	if (rc != -ENOTTY)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index f68c58a..104224f7 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1088,7 +1088,7 @@ static inline int pci_is_managed(struct pci_dev *pdev)
 int pcie_set_mps(struct pci_dev *dev, int mps);
 int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
 			  enum pcie_link_width *width);
-void pcie_flr(struct pci_dev *dev);
+int pcie_flr(struct pci_dev *dev);
 int __pci_reset_function(struct pci_dev *dev);
 int __pci_reset_function_locked(struct pci_dev *dev);
 int pci_reset_function(struct pci_dev *dev);
-- 
1.9.1

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#1738095 — [PATCH 4/5] PCI: wait device ready after pci_pm_reset()

Rev 3.1 Sec 2.3.1 Request Handling Rules says a device can issue CRS
following a D3hot->D0 transition. Add pci_dev_wait() call with 1 second
timeout to see if device is available before returning.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/pci/pci.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index fd4a3b6..074adf9 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3963,6 +3963,7 @@ static int pci_af_flr(struct pci_dev *dev, int probe)
  */
 static int pci_pm_reset(struct pci_dev *dev, int probe)
 {
+	unsigned int delay = dev->d3_delay;
 	u16 csr;
 
 	if (!dev->pm_cap || dev->dev_flags & PCI_DEV_FLAGS_NO_PM_RESET)
@@ -3988,7 +3989,10 @@ static int pci_pm_reset(struct pci_dev *dev, int probe)
 	pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, csr);
 	pci_dev_d3_sleep(dev);
 
-	return 0;
+	if (delay < pci_pm_d3_delay)
+		delay = pci_pm_d3_delay;
+
+	return pci_dev_wait(dev, "PM D3->D0", delay, 1000);
 }
 
 void pci_reset_secondary_bus(struct pci_dev *dev)
-- 
1.9.1

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