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Subject[PATCH 2/4] PCI/DPC/AER: Address Concurrency between AER and DPC
Date
This patch addresses the race condition between AER and DPC for recovery.

Current DPC driver does not do recovery, e.g. calling end-point's driver's
callbacks, which sanitize the device.
DPC driver implements link_reset callback, and calls pci_do_recovery.

Signed-off-by: Oza Pawandeep <poza@codeaurora.org>

diff --git a/drivers/pci/pcie/pcie-dpc.c b/drivers/pci/pcie/pcie-dpc.c
index 2d976a6..e7ced58 100644
--- a/drivers/pci/pcie/pcie-dpc.c
+++ b/drivers/pci/pcie/pcie-dpc.c
@@ -15,6 +15,9 @@
#include <linux/pci.h>
#include <linux/pcieport_if.h>
#include "../pci.h"
+#include "portdrv.h"
+
+static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev);

struct rp_pio_header_log_regs {
u32 dw0;
@@ -67,6 +70,60 @@ struct dpc_dev {
"Memory Request Completion Timeout", /* Bit Position 18 */
};

+static int find_dpc_dev_iter(struct device *device, void *data)
+{
+ struct pcie_port_service_driver *service_driver;
+ struct device **dev;
+
+ dev = (struct device **) data;
+
+ if (device->bus == &pcie_port_bus_type && device->driver) {
+ service_driver = to_service_driver(device->driver);
+ if (service_driver->service == PCIE_PORT_SERVICE_DPC) {
+ *dev = device;
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+struct device *pci_find_dpc_dev(struct pci_dev *pdev)
+{
+ struct device *dev = NULL;
+
+ device_for_each_child(&pdev->dev, &dev, find_dpc_dev_iter);
+
+ return dev;
+}
+
+static int find_dpc_service_iter(struct device *device, void *data)
+{
+ struct pcie_port_service_driver *service_driver, **drv;
+
+ drv = (struct pcie_port_service_driver **) data;
+
+ if (device->bus == &pcie_port_bus_type && device->driver) {
+ service_driver = to_service_driver(device->driver);
+ if (service_driver->service == PCIE_PORT_SERVICE_DPC) {
+ *drv = service_driver;
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+struct pcie_port_service_driver *pci_find_dpc_service(struct pci_dev *dev)
+{
+ struct pcie_port_service_driver *drv = NULL;
+
+ device_for_each_child(&dev->dev, &drv, find_dpc_service_iter);
+
+ return drv;
+}
+EXPORT_SYMBOL(pci_find_dpc_service);
+
static int dpc_wait_rp_inactive(struct dpc_dev *dpc)
{
unsigned long timeout = jiffies + HZ;
@@ -104,11 +161,23 @@ static void dpc_wait_link_inactive(struct dpc_dev *dpc)
dev_warn(dev, "Link state not disabled for DPC event\n");
}

-static void interrupt_event_handler(struct work_struct *work)
+/**
+ * dpc_reset_link - reset link DPC routine
+ * @dev: pointer to Root Port's pci_dev data structure
+ *
+ * Invoked by Port Bus driver when performing link reset at Root Port.
+ */
+static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
{
- struct dpc_dev *dpc = container_of(work, struct dpc_dev, work);
- struct pci_dev *dev, *temp, *pdev = dpc->dev->port;
struct pci_bus *parent = pdev->subordinate;
+ struct pci_dev *dev, *temp;
+ struct dpc_dev *dpc;
+ struct pcie_device *pciedev;
+ struct device *devdpc;
+
+ devdpc = pci_find_dpc_dev(pdev);
+ pciedev = to_pcie_device(devdpc);
+ dpc = get_service_data(pciedev);

pci_lock_rescan_remove();
list_for_each_entry_safe_reverse(dev, temp, &parent->devices,
@@ -125,7 +194,7 @@ static void interrupt_event_handler(struct work_struct *work)

dpc_wait_link_inactive(dpc);
if (dpc->rp && dpc_wait_rp_inactive(dpc))
- return;
+ return PCI_ERS_RESULT_DISCONNECT;
if (dpc->rp && dpc->rp_pio_status) {
pci_write_config_dword(pdev,
dpc->cap_pos + PCI_EXP_DPC_RP_PIO_STATUS,
@@ -135,6 +204,17 @@ static void interrupt_event_handler(struct work_struct *work)

pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,
PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT);
+
+ return PCI_ERS_RESULT_RECOVERED;
+}
+
+static void interrupt_event_handler(struct work_struct *work)
+{
+ struct dpc_dev *dpc = container_of(work, struct dpc_dev, work);
+ struct pci_dev *pdev = dpc->dev->port;
+
+ /* From DPC point of view error is always FATAL. */
+ pci_do_recovery(pdev, PCI_ERR_DPC_FATAL);
}

static void dpc_rp_pio_print_tlp_header(struct device *dev,
@@ -339,6 +419,7 @@ static void dpc_remove(struct pcie_device *dev)
.service = PCIE_PORT_SERVICE_DPC,
.probe = dpc_probe,
.remove = dpc_remove,
+ .reset_link = dpc_reset_link,
};

static int __init dpc_service_init(void)
diff --git a/drivers/pci/pcie/pcie-err.c b/drivers/pci/pcie/pcie-err.c
index d59866c..8bac584 100644
--- a/drivers/pci/pcie/pcie-err.c
+++ b/drivers/pci/pcie/pcie-err.c
@@ -176,7 +176,7 @@ static pci_ers_result_t pci_default_reset_link(struct pci_dev *dev)
return PCI_ERS_RESULT_RECOVERED;
}

-pci_ers_result_t pci_reset_link(struct pci_dev *dev)
+pci_ers_result_t pci_reset_link(struct pci_dev *dev, int severity)
{
struct pci_dev *udev;
pci_ers_result_t status;
@@ -191,7 +191,10 @@ pci_ers_result_t pci_reset_link(struct pci_dev *dev)
}

/* Use the aer driver of the component firstly */
- driver = pci_find_aer_service(udev);
+ if (severity == PCI_ERR_DPC_FATAL)
+ driver = pci_find_dpc_service(udev);
+ else
+ driver = pci_find_aer_service(udev);

if (driver && driver->reset_link) {
status = driver->reset_link(udev);
@@ -280,7 +283,8 @@ void pci_do_recovery(struct pci_dev *dev, int severity)

mutex_lock(&pci_err_recovery_lock);

- if (severity == PCI_ERR_AER_FATAL)
+ if ((severity == PCI_ERR_AER_FATAL) ||
+ (severity == PCI_ERR_DPC_FATAL))
state = pci_channel_io_frozen;
else
state = pci_channel_io_normal;
@@ -290,8 +294,9 @@ void pci_do_recovery(struct pci_dev *dev, int severity)
"error_detected",
pci_report_error_detected);

- if (severity == PCI_ERR_AER_FATAL) {
- result = pci_reset_link(dev);
+ if ((severity == PCI_ERR_AER_FATAL) ||
+ (severity == PCI_ERR_DPC_FATAL)) {
+ result = pci_reset_link(dev, severity);
if (result != PCI_ERS_RESULT_RECOVERED)
goto failed;
}
diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
index 4f1992d..b013e24 100644
--- a/drivers/pci/pcie/portdrv.h
+++ b/drivers/pci/pcie/portdrv.h
@@ -80,4 +80,5 @@ static inline void pcie_port_platform_notify(struct pci_dev *port, int *mask){}
#endif /* !CONFIG_ACPI */

struct pcie_port_service_driver *pci_find_aer_service(struct pci_dev *dev);
+struct pcie_port_service_driver *pci_find_dpc_service(struct pci_dev *dev);
#endif /* _PORTDRV_H_ */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 083408e..123ee15 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2005,6 +2005,7 @@ static inline resource_size_t pci_iov_resource_size(struct pci_dev *dev, int res
#define PCI_ERR_AER_NONFATAL 0
#define PCI_ERR_AER_FATAL 1
#define PCI_ERR_AER_CORRECTABLE 2
+#define PCI_ERR_DPC_FATAL 4

pci_ers_result_t pci_broadcast_error_message(struct pci_dev *dev,
enum pci_channel_state state,
@@ -2014,7 +2015,7 @@ pci_ers_result_t pci_broadcast_error_message(struct pci_dev *dev,
int pci_report_slot_reset(struct pci_dev *dev, void *data);
int pci_report_resume(struct pci_dev *dev, void *data);
int pci_report_error_detected(struct pci_dev *dev, void *data);
-pci_ers_result_t pci_reset_link(struct pci_dev *dev);
+pci_ers_result_t pci_reset_link(struct pci_dev *dev, int severity);
pci_ers_result_t pci_merge_result(enum pci_ers_result orig,
enum pci_ers_result new);
void pci_do_recovery(struct pci_dev *dev, int severity);
--
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.,
a Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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