Commit bdb5ac85777d ("PCI/ERR: Handle fatal error recovery")
merged fatal and non-fatal error recovery paths, and also made
recovery code depend on hotplug handler for "remove affected
device + rescan" support. But this change also complicated the
error recovery path and which in turn led to the following
issues.
1. We depend on hotplug handler for removing the affected
devices/drivers on DLLSC LINK down event (on DPC event
trigger) and DPC handler for handling the error recovery. Since
both handlers operate on same set of affected devices, it leads
to race condition, which in turn leads to NULL pointer
exceptions or error recovery failures.You can find more details
about this issue in following link.
https://lore.kernel.org/linux-pci/[email protected]/T/#t
2. For non-hotplug capable devices fatal (DPC) error recovery
is currently broken. Current fatal error recovery implementation
relies on PCIe hotplug (pciehp) handler for detaching and
re-enumerating the affected devices/drivers. So when dealing with
non-hotplug capable devices, recovery code does not restore the state
of the affected devices correctly. You can find more details about
this issue in the following links.
https://lore.kernel.org/linux-pci/[email protected]/
https://lore.kernel.org/linux-pci/12115.1588207324@famine/
https://lore.kernel.org/linux-pci/0e6f89cd6b9e4a72293cc90fafe93487d7c2d295.1585000084.git.sathyanarayanan.kuppuswamy@linux.intel.com/
In order to fix the above two issues, we should stop relying on hotplug
handler for cleaning the affected devices/drivers and let error recovery
handler own this functionality. So this patch reverts Commit bdb5ac85777d
("PCI/ERR: Handle fatal error recovery") and re-introduce the "remove
affected device + rescan" functionality in fatal error recovery handler.
Also holding pci_lock_rescan_remove() will prevent the race between hotplug
and DPC handler.
Fixes: bdb5ac85777d ("PCI/ERR: Handle fatal error recovery")
Signed-off-by: Kuppuswamy Sathyanarayanan <[email protected]>
Reviewed-by: Sinan Kaya <[email protected]>
---
Changes since v4:
* Added new interfaces for error recovery (pcie_do_fatal_recovery()
and pcie_do_nonfatal_recovery()).
Documentation/PCI/pci-error-recovery.rst | 47 ++++++++++------
Documentation/PCI/pcieaer-howto.rst | 2 +-
drivers/pci/pci.h | 5 +-
drivers/pci/pcie/aer.c | 10 ++--
drivers/pci/pcie/dpc.c | 2 +-
drivers/pci/pcie/edr.c | 2 +-
drivers/pci/pcie/err.c | 70 ++++++++++++++++++------
7 files changed, 94 insertions(+), 44 deletions(-)
diff --git a/Documentation/PCI/pci-error-recovery.rst b/Documentation/PCI/pci-error-recovery.rst
index 84ceebb08cac..830c8af5838b 100644
--- a/Documentation/PCI/pci-error-recovery.rst
+++ b/Documentation/PCI/pci-error-recovery.rst
@@ -115,7 +115,7 @@ The actual steps taken by a platform to recover from a PCI error
event will be platform-dependent, but will follow the general
sequence described below.
-STEP 0: Error Event
+STEP 0: Error Event: ERR_NONFATAL
-------------------
A PCI bus error is detected by the PCI hardware. On powerpc, the slot
is isolated, in that all I/O is blocked: all reads return 0xffffffff,
@@ -160,10 +160,10 @@ particular, if the platform doesn't isolate slots), and recovery
proceeds to STEP 2 (MMIO Enable).
If any driver requested a slot reset (by returning PCI_ERS_RESULT_NEED_RESET),
-then recovery proceeds to STEP 4 (Slot Reset).
+then recovery proceeds to STEP 3 (Slot Reset).
If the platform is unable to recover the slot, the next step
-is STEP 6 (Permanent Failure).
+is STEP 5 (Permanent Failure).
.. note::
@@ -198,7 +198,7 @@ reset or some such, but not restart operations. This callback is made if
all drivers on a segment agree that they can try to recover and if no automatic
link reset was performed by the HW. If the platform can't just re-enable IOs
without a slot reset or a link reset, it will not call this callback, and
-instead will have gone directly to STEP 3 (Link Reset) or STEP 4 (Slot Reset)
+instead will have gone directly to STEP 3 (Slot Reset)
.. note::
@@ -233,18 +233,12 @@ The driver should return one of the following result codes:
The next step taken depends on the results returned by the drivers.
If all drivers returned PCI_ERS_RESULT_RECOVERED, then the platform
-proceeds to either STEP3 (Link Reset) or to STEP 5 (Resume Operations).
+proceeds to STEP 4 (Resume Operations).
If any driver returned PCI_ERS_RESULT_NEED_RESET, then the platform
-proceeds to STEP 4 (Slot Reset)
+proceeds to STEP 3 (Slot Reset)
-STEP 3: Link Reset
-------------------
-The platform resets the link. This is a PCI-Express specific step
-and is done whenever a fatal error has been detected that can be
-"solved" by resetting the link.
-
-STEP 4: Slot Reset
+STEP 3: Slot Reset
------------------
In response to a return value of PCI_ERS_RESULT_NEED_RESET, the
@@ -322,7 +316,7 @@ PCI card types::
+ pdev->needs_freset = 1;
+
-Platform proceeds either to STEP 5 (Resume Operations) or STEP 6 (Permanent
+Platform proceeds either to STEP 4 (Resume Operations) or STEP 5 (Permanent
Failure).
.. note::
@@ -332,7 +326,7 @@ Failure).
However, it probably should.
-STEP 5: Resume Operations
+STEP 4: Resume Operations
-------------------------
The platform will call the resume() callback on all affected device
drivers if all drivers on the segment have returned
@@ -344,7 +338,7 @@ a result code.
At this point, if a new error happens, the platform will restart
a new error recovery sequence.
-STEP 6: Permanent Failure
+STEP 5: Permanent Failure
-------------------------
A "permanent failure" has occurred, and the platform cannot recover
the device. The platform will call error_detected() with a
@@ -367,6 +361,27 @@ errors. See the discussion in powerpc/eeh-pci-error-recovery.txt
for additional detail on real-life experience of the causes of
software errors.
+STEP 0: Error Event: ERR_FATAL
+--------------------
+PCI bus error is detected by the PCI hardware. On powerpc, the slot is
+isolated, in that all I/O is blocked: all reads return 0xffffffff, all
+writes are ignored.
+
+STEP 1: Remove devices
+---------------------
+Platform removes the devices depending on the error agent, it could be
+this port for all subordinates or upstream component (likely downstream
+port)
+
+STEP 2: Reset link
+---------------------
+The platform resets the link. This is a PCI-Express specific step and is
+done whenever a fatal error has been detected that can be "solved" by
+resetting the link.
+
+STEP 3: Re-enumerate the devices
+---------------------
+Initiates the re-enumeration.
Conclusion; General Remarks
---------------------------
diff --git a/Documentation/PCI/pcieaer-howto.rst b/Documentation/PCI/pcieaer-howto.rst
index 0b36b9ebfa4b..9528cfd9449b 100644
--- a/Documentation/PCI/pcieaer-howto.rst
+++ b/Documentation/PCI/pcieaer-howto.rst
@@ -206,7 +206,7 @@ error_detected(dev, pci_channel_io_frozen) to all drivers within
a hierarchy in question. Then, performing link reset at upstream is
necessary. As different kinds of devices might use different approaches
to reset link, AER port service driver is required to provide the
-function to reset link via callback parameter of pcie_do_recovery()
+function to reset link via callback parameter of pcie_do_fatal_recovery()
function. If reset_link is not NULL, recovery function will use it
to reset the link. If error_detected returns PCI_ERS_RESULT_CAN_RECOVER
and reset_link returns PCI_ERS_RESULT_RECOVERED, the error handling goes
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index fa12f7cbc1a0..b3e1571107b5 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -555,8 +555,9 @@ static inline int pci_dev_specific_disable_acs_redir(struct pci_dev *dev)
#endif
/* PCI error reporting and recovery */
-pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
- pci_channel_state_t state,
+pci_ers_result_t pcie_do_nonfatal_recovery(struct pci_dev *dev);
+
+pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
pci_ers_result_t (*reset_link)(struct pci_dev *pdev));
bool pcie_wait_for_link(struct pci_dev *pdev, bool active);
diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
index 65dff5f3457a..f3e70bb9b30d 100644
--- a/drivers/pci/pcie/aer.c
+++ b/drivers/pci/pcie/aer.c
@@ -947,9 +947,9 @@ static void handle_error_source(struct pci_dev *dev, struct aer_err_info *info)
if (pcie_aer_is_native(dev))
pcie_clear_device_status(dev);
} else if (info->severity == AER_NONFATAL)
- pcie_do_recovery(dev, pci_channel_io_normal, aer_root_reset);
+ pcie_do_nonfatal_recovery(dev);
else if (info->severity == AER_FATAL)
- pcie_do_recovery(dev, pci_channel_io_frozen, aer_root_reset);
+ pcie_do_fatal_recovery(dev, aer_root_reset);
pci_dev_put(dev);
}
@@ -985,11 +985,9 @@ static void aer_recover_work_func(struct work_struct *work)
}
cper_print_aer(pdev, entry.severity, entry.regs);
if (entry.severity == AER_NONFATAL)
- pcie_do_recovery(pdev, pci_channel_io_normal,
- aer_root_reset);
+ pcie_do_nonfatal_recovery(pdev);
else if (entry.severity == AER_FATAL)
- pcie_do_recovery(pdev, pci_channel_io_frozen,
- aer_root_reset);
+ pcie_do_fatal_recovery(pdev, aer_root_reset);
pci_dev_put(pdev);
}
}
diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
index daa9a4153776..74e7d1da3cf0 100644
--- a/drivers/pci/pcie/dpc.c
+++ b/drivers/pci/pcie/dpc.c
@@ -233,7 +233,7 @@ static irqreturn_t dpc_handler(int irq, void *context)
dpc_process_error(pdev);
/* We configure DPC so it only triggers on ERR_FATAL */
- pcie_do_recovery(pdev, pci_channel_io_frozen, dpc_reset_link);
+ pcie_do_fatal_recovery(pdev, dpc_reset_link);
return IRQ_HANDLED;
}
diff --git a/drivers/pci/pcie/edr.c b/drivers/pci/pcie/edr.c
index a6b9b479b97a..87379bc566f6 100644
--- a/drivers/pci/pcie/edr.c
+++ b/drivers/pci/pcie/edr.c
@@ -183,7 +183,7 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
* or ERR_NONFATAL, since the link is already down, use the FATAL
* error recovery path for both cases.
*/
- estate = pcie_do_recovery(edev, pci_channel_io_frozen, dpc_reset_link);
+ estate = pcie_do_fatal_recovery(edev, dpc_reset_link);
send_ost:
diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c
index 315a4d559c4c..380486b6158c 100644
--- a/drivers/pci/pcie/err.c
+++ b/drivers/pci/pcie/err.c
@@ -79,11 +79,6 @@ static int report_error_detected(struct pci_dev *dev,
return 0;
}
-static int report_frozen_detected(struct pci_dev *dev, void *data)
-{
- return report_error_detected(dev, pci_channel_io_frozen, data);
-}
-
static int report_normal_detected(struct pci_dev *dev, void *data)
{
return report_error_detected(dev, pci_channel_io_normal, data);
@@ -146,9 +141,59 @@ static int report_resume(struct pci_dev *dev, void *data)
return 0;
}
-pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
- pci_channel_state_t state,
+static pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
+{
+ struct pci_dev *udev;
+ struct pci_bus *parent;
+ struct pci_dev *pdev, *temp;
+ pci_ers_result_t result;
+
+ if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
+ udev = dev;
+ else
+ udev = dev->bus->self;
+
+ parent = udev->subordinate;
+ pci_walk_bus(parent, pci_dev_set_disconnected, NULL);
+
+ pci_lock_rescan_remove();
+ pci_dev_get(dev);
+ list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
+ bus_list) {
+ pci_stop_and_remove_bus_device(pdev);
+ }
+
+ result = reset_link(udev);
+
+ if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
+ /*
+ * If the error is reported by a bridge, we think this error
+ * is related to the downstream link of the bridge, so we
+ * do error recovery on all subordinates of the bridge instead
+ * of the bridge and clear the error status of the bridge.
+ */
+ pci_aer_clear_fatal_status(dev);
+ if (pcie_aer_is_native(dev))
+ pcie_clear_device_status(dev);
+ }
+
+ if (result == PCI_ERS_RESULT_RECOVERED) {
+ if (pcie_wait_for_link(udev, true))
+ pci_rescan_bus(udev->bus);
+ pci_info(dev, "Device recovery from fatal error successful\n");
+ } else {
+ pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
+ pci_info(dev, "Device recovery from fatal error failed\n");
+ }
+
+ pci_dev_put(dev);
+ pci_unlock_rescan_remove();
+
+ return result;
+}
+
+pci_ers_result_t pcie_do_nonfatal_recovery(struct pci_dev *dev)
{
pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
struct pci_bus *bus;
@@ -164,16 +209,7 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
bus = dev->subordinate;
pci_dbg(dev, "broadcast error_detected message\n");
- if (state == pci_channel_io_frozen) {
- pci_walk_bus(bus, report_frozen_detected, &status);
- status = reset_link(dev);
- if (status != PCI_ERS_RESULT_RECOVERED) {
- pci_warn(dev, "link reset failed\n");
- goto failed;
- }
- } else {
- pci_walk_bus(bus, report_normal_detected, &status);
- }
+ pci_walk_bus(bus, report_normal_detected, &status);
if (status == PCI_ERS_RESULT_CAN_RECOVER) {
status = PCI_ERS_RESULT_RECOVERED;
--
2.17.1
Hi Kuppuswamy,
I love your patch! Yet something to improve:
[auto build test ERROR on pci/next]
[also build test ERROR on v5.9]
[cannot apply to next-20201013]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Kuppuswamy-Sathyanarayanan/PCI-ERR-Call-pci_bus_reset-before-calling-slot_reset-callback/20201014-172736
base: https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next
config: xtensa-allyesconfig (attached as .config)
compiler: xtensa-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/7c892978aa57817ac512ea311d0d87dd6e1ced80
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Kuppuswamy-Sathyanarayanan/PCI-ERR-Call-pci_bus_reset-before-calling-slot_reset-callback/20201014-172736
git checkout 7c892978aa57817ac512ea311d0d87dd6e1ced80
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=xtensa
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
>> drivers/pci/pcie/err.c:144:25: error: static declaration of 'pcie_do_fatal_recovery' follows non-static declaration
144 | static pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
| ^~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/pci/pcie/err.c:21:
drivers/pci/pcie/../pci.h:559:18: note: previous declaration of 'pcie_do_fatal_recovery' was here
559 | pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
| ^~~~~~~~~~~~~~~~~~~~~~
drivers/pci/pcie/err.c:144:25: warning: 'pcie_do_fatal_recovery' defined but not used [-Wunused-function]
144 | static pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
| ^~~~~~~~~~~~~~~~~~~~~~
vim +/pcie_do_fatal_recovery +144 drivers/pci/pcie/err.c
143
> 144 static pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
145 pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
146 {
147 struct pci_dev *udev;
148 struct pci_bus *parent;
149 struct pci_dev *pdev, *temp;
150 pci_ers_result_t result;
151
152 if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
153 udev = dev;
154 else
155 udev = dev->bus->self;
156
157 parent = udev->subordinate;
158 pci_walk_bus(parent, pci_dev_set_disconnected, NULL);
159
160 pci_lock_rescan_remove();
161 pci_dev_get(dev);
162 list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
163 bus_list) {
164 pci_stop_and_remove_bus_device(pdev);
165 }
166
167 result = reset_link(udev);
168
169 if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
170 /*
171 * If the error is reported by a bridge, we think this error
172 * is related to the downstream link of the bridge, so we
173 * do error recovery on all subordinates of the bridge instead
174 * of the bridge and clear the error status of the bridge.
175 */
176 pci_aer_clear_fatal_status(dev);
177 if (pcie_aer_is_native(dev))
178 pcie_clear_device_status(dev);
179 }
180
181 if (result == PCI_ERS_RESULT_RECOVERED) {
182 if (pcie_wait_for_link(udev, true))
183 pci_rescan_bus(udev->bus);
184 pci_info(dev, "Device recovery from fatal error successful\n");
185 } else {
186 pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
187 pci_info(dev, "Device recovery from fatal error failed\n");
188 }
189
190 pci_dev_put(dev);
191 pci_unlock_rescan_remove();
192
193 return result;
194 }
195
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]
Hi Kuppuswamy,
I love your patch! Yet something to improve:
[auto build test ERROR on pci/next]
[also build test ERROR on v5.9]
[cannot apply to next-20201013]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Kuppuswamy-Sathyanarayanan/PCI-ERR-Call-pci_bus_reset-before-calling-slot_reset-callback/20201014-172736
base: https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git next
config: x86_64-randconfig-a004-20201014 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project e7fe3c6dfede8d5781bd000741c3dea7088307a4)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install x86_64 cross compiling tool for clang build
# apt-get install binutils-x86-64-linux-gnu
# https://github.com/0day-ci/linux/commit/7c892978aa57817ac512ea311d0d87dd6e1ced80
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Kuppuswamy-Sathyanarayanan/PCI-ERR-Call-pci_bus_reset-before-calling-slot_reset-callback/20201014-172736
git checkout 7c892978aa57817ac512ea311d0d87dd6e1ced80
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
>> drivers/pci/pcie/err.c:144:25: error: static declaration of 'pcie_do_fatal_recovery' follows non-static declaration
static pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
^
drivers/pci/pcie/../pci.h:559:18: note: previous declaration is here
pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
^
1 error generated.
vim +/pcie_do_fatal_recovery +144 drivers/pci/pcie/err.c
143
> 144 static pci_ers_result_t pcie_do_fatal_recovery(struct pci_dev *dev,
145 pci_ers_result_t (*reset_link)(struct pci_dev *pdev))
146 {
147 struct pci_dev *udev;
148 struct pci_bus *parent;
149 struct pci_dev *pdev, *temp;
150 pci_ers_result_t result;
151
152 if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
153 udev = dev;
154 else
155 udev = dev->bus->self;
156
157 parent = udev->subordinate;
158 pci_walk_bus(parent, pci_dev_set_disconnected, NULL);
159
160 pci_lock_rescan_remove();
161 pci_dev_get(dev);
162 list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
163 bus_list) {
164 pci_stop_and_remove_bus_device(pdev);
165 }
166
167 result = reset_link(udev);
168
169 if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
170 /*
171 * If the error is reported by a bridge, we think this error
172 * is related to the downstream link of the bridge, so we
173 * do error recovery on all subordinates of the bridge instead
174 * of the bridge and clear the error status of the bridge.
175 */
176 pci_aer_clear_fatal_status(dev);
177 if (pcie_aer_is_native(dev))
178 pcie_clear_device_status(dev);
179 }
180
181 if (result == PCI_ERS_RESULT_RECOVERED) {
182 if (pcie_wait_for_link(udev, true))
183 pci_rescan_bus(udev->bus);
184 pci_info(dev, "Device recovery from fatal error successful\n");
185 } else {
186 pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
187 pci_info(dev, "Device recovery from fatal error failed\n");
188 }
189
190 pci_dev_put(dev);
191 pci_unlock_rescan_remove();
192
193 return result;
194 }
195
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]