[PATCH AUTOSEL 4.19 081/191] PCI/ERR: Use slot reset if available

Sasha Levin
2019-11-10T03:13:07Z

From: Keith Busch <keith.busch@intel.com>

[ Upstream commit c4eed62a214330908eec11b0dc170d34fa50b412 ]

The secondary bus reset may have link side effects that a hotplug capable
port may incorrectly react to. Use the slot specific reset for hotplug
ports, fixing the undesirable link down-up handling during error
recovering.

Signed-off-by: Keith Busch <keith.busch@intel.com>
[bhelgaas: fold in
https://lore.kernel.org/linux-pci/20180926152326.14821-1-keith.busch@intel.com
for issue reported by Stephen Rothwell <sfr@canb.auug.org.au>]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Sinan Kaya <okaya@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pci/pci.c | 37 +++++++++++++++++++++++++++++++++++++
drivers/pci/pci.h | 2 ++
drivers/pci/pcie/aer.c | 2 +-
drivers/pci/pcie/err.c | 2 +-
drivers/pci/slot.c | 1 -
5 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2baf1f82f8933..c9f51fc24563c 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -35,6 +35,8 @@
#include <linux/aer.h>
#include "pci.h"

+DEFINE_MUTEX(pci_slot_mutex);
+
const char *pci_power_names[] = {
"error", "D0", "D1", "D2", "D3hot", "D3cold", "unknown",
};
@@ -5191,6 +5193,41 @@ static int pci_bus_reset(struct pci_bus *bus, int probe)
return ret;
}

+/**
+ * pci_bus_error_reset - reset the bridge's subordinate bus
+ * @bridge: The parent device that connects to the bus to reset
+ *
+ * This function will first try to reset the slots on this bus if the method is
+ * available. If slot reset fails or is not available, this will fall back to a
+ * secondary bus reset.
+ */
+int pci_bus_error_reset(struct pci_dev *bridge)
+{
+ struct pci_bus *bus = bridge->subordinate;
+ struct pci_slot *slot;
+
+ if (!bus)
+ return -ENOTTY;
+
+ mutex_lock(&pci_slot_mutex);
+ if (list_empty(&bus->slots))
+ goto bus_reset;
+
+ list_for_each_entry(slot, &bus->slots, list)
+ if (pci_probe_reset_slot(slot))
+ goto bus_reset;
+
+ list_for_each_entry(slot, &bus->slots, list)
+ if (pci_slot_reset(slot, 0))
+ goto bus_reset;
+
+ mutex_unlock(&pci_slot_mutex);
+ return 0;
+bus_reset:
+ mutex_unlock(&pci_slot_mutex);
+ return pci_bus_reset(bridge->subordinate, 0);
+}
+
/**
* pci_probe_reset_bus - probe whether a PCI bus can be reset
* @bus: PCI bus to probe
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index ab25752f00d96..e9ede82ee2c25 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -35,6 +35,7 @@ int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vmai,

int pci_probe_reset_function(struct pci_dev *dev);
int pci_bridge_secondary_bus_reset(struct pci_dev *dev);
+int pci_bus_error_reset(struct pci_dev *dev);

/**
* struct pci_platform_pm_ops - Firmware PM callbacks
@@ -136,6 +137,7 @@ static inline void pci_remove_legacy_files(struct pci_bus *bus) { return; }

/* Lock for read/write access to pci device and bus lists */
extern struct rw_semaphore pci_bus_sem;
+extern struct mutex pci_slot_mutex;

extern raw_spinlock_t pci_lock;

diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 5c3ea7254c6ae..1563e22600eca 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -1528,7 +1528,7 @@ static pci_ers_result_t aer_root_reset(struct pci_dev *dev)
reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK;
pci_write_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, reg32);

- rc = pci_bridge_secondary_bus_reset(dev);
+ rc = pci_bus_error_reset(dev);
pci_printk(KERN_DEBUG, dev, "Root Port link has been reset\n");

/* Clear Root Error Status */
diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index 708fd3a0d6466..12c1205e1d804 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -177,7 +177,7 @@ static pci_ers_result_t default_reset_link(struct pci_dev *dev)
{
int rc;

- rc = pci_bridge_secondary_bus_reset(dev);
+ rc = pci_bus_error_reset(dev);
pci_printk(KERN_DEBUG, dev, "downstream link has been reset\n");
return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_RECOVERED;
}
diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c
index e634229ece895..a32897f83ee51 100644
--- a/drivers/pci/slot.c
+++ b/drivers/pci/slot.c
@@ -14,7 +14,6 @@

struct kset *pci_slots_kset;
EXPORT_SYMBOL_GPL(pci_slots_kset);
-static DEFINE_MUTEX(pci_slot_mutex);

static ssize_t pci_slot_attr_show(struct kobject *kobj,
struct attribute *attr, char *buf)
--
2.20.1