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Date: Fri, 23 Nov 2012 15:47:42 +0800
From: Huang Ying <ying.huang@...el.com>
To: Ben Hutchings <ben@...adent.org.uk>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org, stable@...r.kernel.org,
alan@...rguk.ukuu.org.uk, Bjorn Helgaas <bhelgaas@...gle.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Zhang Yanmin <yanmin.zhang@...el.com>
Subject: Re: [ 02/38] PCI/PM: Fix deadlock when unbinding device if parent
in D3cold
On Fri, 2012-11-23 at 11:09 +0800, Huang Ying wrote:
> On Fri, 2012-11-23 at 02:35 +0000, Ben Hutchings wrote:
> > On Wed, 2012-11-21 at 16:39 -0800, Greg Kroah-Hartman wrote:
> > > 3.0-stable review patch. If anyone has any objections, please let me know.
> > >
> > > ------------------
> > >
> > > From: Huang Ying <ying.huang@...el.com>
> > >
> > > 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.
> > [...]
> >
> > What about eeh_report_error() in
> > arch/powerpc/platforms/pseries/eeh_driver.c?
>
> En... Because pci_walk_bus() invocation is removed in 3.7, so this
> patch is only valid for 3.7. We need another version for 3.6.
Here is the patch for 3.6. I have no powerpc machine, so build test
only.
Subject: [BUGFIX] PCI/PM: Fix deadlock when unbind device if its parent in D3cold
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) <--- dead lock here
If we do not do device_lock in pci_walk_bus, we can avoid dead lock.
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 dead lock as follow:
- 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 <ying.huang@...el.com>
Cc: Zhang Yanmin <yanmin.zhang@...el.com>
---
arch/powerpc/platforms/pseries/eeh_driver.c | 51 ++++++++++++++++++----------
drivers/pci/bus.c | 3 -
drivers/pci/pcie/aer/aerdrv_core.c | 20 ++++++++--
3 files changed, 50 insertions(+), 24 deletions(-)
--- a/arch/powerpc/platforms/pseries/eeh_driver.c
+++ b/arch/powerpc/platforms/pseries/eeh_driver.c
@@ -126,18 +126,19 @@ static void eeh_enable_irq(struct pci_de
static int eeh_report_error(struct pci_dev *dev, void *userdata)
{
enum pci_ers_result rc, *res = userdata;
- struct pci_driver *driver = dev->driver;
+ struct pci_driver *driver;
+ device_lock(&dev->dev);
dev->error_state = pci_channel_io_frozen;
-
+ driver = dev->driver;
if (!driver)
- return 0;
+ goto out;
eeh_disable_irq(dev);
if (!driver->err_handler ||
!driver->err_handler->error_detected)
- return 0;
+ goto out;
rc = driver->err_handler->error_detected(dev, pci_channel_io_frozen);
@@ -145,6 +146,8 @@ static int eeh_report_error(struct pci_d
if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
if (*res == PCI_ERS_RESULT_NONE) *res = rc;
+out:
+ device_unlock(&dev->dev);
return 0;
}
@@ -160,12 +163,14 @@ static int eeh_report_error(struct pci_d
static int eeh_report_mmio_enabled(struct pci_dev *dev, void *userdata)
{
enum pci_ers_result rc, *res = userdata;
- struct pci_driver *driver = dev->driver;
+ struct pci_driver *driver;
+ device_lock(&dev->dev);
+ driver = dev->driver;
if (!driver ||
!driver->err_handler ||
!driver->err_handler->mmio_enabled)
- return 0;
+ goto out;
rc = driver->err_handler->mmio_enabled(dev);
@@ -173,6 +178,8 @@ static int eeh_report_mmio_enabled(struc
if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
if (*res == PCI_ERS_RESULT_NONE) *res = rc;
+out:
+ device_unlock(&dev->dev);
return 0;
}
@@ -189,10 +196,12 @@ static int eeh_report_mmio_enabled(struc
static int eeh_report_reset(struct pci_dev *dev, void *userdata)
{
enum pci_ers_result rc, *res = userdata;
- struct pci_driver *driver = dev->driver;
+ struct pci_driver *driver;
+ device_lock(&dev->dev);
+ driver = dev->driver;
if (!driver)
- return 0;
+ goto out;
dev->error_state = pci_channel_io_normal;
@@ -200,7 +209,7 @@ static int eeh_report_reset(struct pci_d
if (!driver->err_handler ||
!driver->err_handler->slot_reset)
- return 0;
+ goto out;
rc = driver->err_handler->slot_reset(dev);
if ((*res == PCI_ERS_RESULT_NONE) ||
@@ -208,6 +217,8 @@ static int eeh_report_reset(struct pci_d
if (*res == PCI_ERS_RESULT_DISCONNECT &&
rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
+out:
+ device_unlock(&dev->dev);
return 0;
}
@@ -222,21 +233,24 @@ static int eeh_report_reset(struct pci_d
*/
static int eeh_report_resume(struct pci_dev *dev, void *userdata)
{
- struct pci_driver *driver = dev->driver;
+ struct pci_driver *driver;
+ device_lock(&dev->dev);
dev->error_state = pci_channel_io_normal;
-
+ driver = dev->driver;
if (!driver)
- return 0;
+ goto out;
eeh_enable_irq(dev);
if (!driver->err_handler ||
!driver->err_handler->resume)
- return 0;
+ goto out;
driver->err_handler->resume(dev);
+out:
+ device_unlock(&dev->dev);
return 0;
}
@@ -250,21 +264,24 @@ static int eeh_report_resume(struct pci_
*/
static int eeh_report_failure(struct pci_dev *dev, void *userdata)
{
- struct pci_driver *driver = dev->driver;
+ struct pci_driver *driver;
+ device_lock(&dev->dev);
dev->error_state = pci_channel_io_perm_failure;
-
+ driver = dev->driver;
if (!driver)
- return 0;
+ goto out;
eeh_disable_irq(dev);
if (!driver->err_handler ||
!driver->err_handler->error_detected)
- return 0;
+ goto out;
driver->err_handler->error_detected(dev, pci_channel_io_perm_failure);
+out:
+ device_unlock(&dev->dev);
return 0;
}
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -316,10 +316,7 @@ 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;
}
--
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