This is a note to let you know that I've just added the patch titled
PCI/PM: Fix deadlock when unbinding device if parent in D3cold
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-pm-fix-deadlock-when-unbinding-device-if-parent-in-d3cold.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 90b5c1d7c45eeb622302680ff96ed30c1a2b6f0e Mon Sep 17 00:00:00 2001
From: Huang Ying <[email protected]>
Date: Wed, 24 Oct 2012 14:54:13 +0800
Subject: PCI/PM: Fix deadlock when unbinding device if parent in D3cold
From: Huang Ying <[email protected]>
commit 90b5c1d7c45eeb622302680ff96ed30c1a2b6f0e upstream.
If a PCI device and its parents are put into D3cold, unbinding the
device will trigger deadlock as follow:
- driver_unbind
- device_release_driver
- device_lock(dev) <--- previous lock here
- __device_release_driver
- pm_runtime_get_sync
...
- rpm_resume(dev)
- rpm_resume(dev->parent)
...
- pci_pm_runtime_resume
...
- pci_set_power_state
- __pci_start_power_transition
- pci_wakeup_bus(dev->parent->subordinate)
- pci_walk_bus
- device_lock(dev) <--- deadlock here
If we do not do device_lock in pci_walk_bus, we can avoid deadlock.
Device_lock in pci_walk_bus is introduced in commit:
d71374dafbba7ec3f67371d3b7e9f6310a588808, corresponding email thread
is: https://lkml.org/lkml/2006/5/26/38. The patch author Zhang Yanmin
said device_lock is added to pci_walk_bus because:
Some error handling functions call pci_walk_bus. For example, PCIe
aer. Here we lock the device, so the driver wouldn't detach from the
device, as the cb might call driver's callback function.
So I fixed the deadlock as follows:
- remove device_lock from pci_walk_bus
- add device_lock into callback if callback will call driver's callback
I checked pci_walk_bus users one by one, and found only PCIe aer needs
device lock.
Signed-off-by: Huang Ying <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
CC: Zhang Yanmin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/pci/bus.c | 3 ---
drivers/pci/pcie/aer/aerdrv_core.c | 20 ++++++++++++++++----
2 files changed, 16 insertions(+), 7 deletions(-)
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -314,10 +314,7 @@ void pci_walk_bus(struct pci_bus *top, i
} else
next = dev->bus_list.next;
- /* Run device routines with the device locked */
- device_lock(&dev->dev);
retval = cb(dev, userdata);
- device_unlock(&dev->dev);
if (retval)
break;
}
--- a/drivers/pci/pcie/aer/aerdrv_core.c
+++ b/drivers/pci/pcie/aer/aerdrv_core.c
@@ -244,6 +244,7 @@ static int report_error_detected(struct
struct aer_broadcast_data *result_data;
result_data = (struct aer_broadcast_data *) data;
+ device_lock(&dev->dev);
dev->error_state = result_data->state;
if (!dev->driver ||
@@ -262,12 +263,14 @@ static int report_error_detected(struct
dev->driver ?
"no AER-aware driver" : "no driver");
}
- return 0;
+ goto out;
}
err_handler = dev->driver->err_handler;
vote = err_handler->error_detected(dev, result_data->state);
result_data->result = merge_result(result_data->result, vote);
+out:
+ device_unlock(&dev->dev);
return 0;
}
@@ -278,14 +281,17 @@ static int report_mmio_enabled(struct pc
struct aer_broadcast_data *result_data;
result_data = (struct aer_broadcast_data *) data;
+ device_lock(&dev->dev);
if (!dev->driver ||
!dev->driver->err_handler ||
!dev->driver->err_handler->mmio_enabled)
- return 0;
+ goto out;
err_handler = dev->driver->err_handler;
vote = err_handler->mmio_enabled(dev);
result_data->result = merge_result(result_data->result, vote);
+out:
+ device_unlock(&dev->dev);
return 0;
}
@@ -296,14 +302,17 @@ static int report_slot_reset(struct pci_
struct aer_broadcast_data *result_data;
result_data = (struct aer_broadcast_data *) data;
+ device_lock(&dev->dev);
if (!dev->driver ||
!dev->driver->err_handler ||
!dev->driver->err_handler->slot_reset)
- return 0;
+ goto out;
err_handler = dev->driver->err_handler;
vote = err_handler->slot_reset(dev);
result_data->result = merge_result(result_data->result, vote);
+out:
+ device_unlock(&dev->dev);
return 0;
}
@@ -311,15 +320,18 @@ static int report_resume(struct pci_dev
{
struct pci_error_handlers *err_handler;
+ device_lock(&dev->dev);
dev->error_state = pci_channel_io_normal;
if (!dev->driver ||
!dev->driver->err_handler ||
!dev->driver->err_handler->resume)
- return 0;
+ goto out;
err_handler = dev->driver->err_handler;
err_handler->resume(dev);
+out:
+ device_unlock(&dev->dev);
return 0;
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/pci-pm-fix-deadlock-when-unbinding-device-if-parent-in-d3cold.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
