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Message-ID: <1355213572.7216.140.camel@yhuang-dev> Date: Tue, 11 Dec 2012 16:12:52 +0800 From: Huang Ying <ying.huang@...el.com> To: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Cc: Ben Hutchings <ben@...adent.org.uk>, 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, 2012-11-30 at 10:54 +0800, Huang Ying wrote: > On Thu, 2012-11-29 at 18:01 -0800, Greg Kroah-Hartman wrote: > > On Fri, Nov 23, 2012 at 03:47:42PM +0800, Huang Ying wrote: > > > 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 ++++++++++++++++++---------- > > > > Due to me applying a power pci patch, > > feadf7c0a1a7c08c74bebb4a13b755f8c40e3bbc in Linus's tree to 3.6-stable, > > this patch doesn't apply here anymore. > > > > Because that patch is in the tree, is it now just safe to take your > > original, unmodified, version of this patch for 3.6-stable? > > No. My original version does not work. I need to rebase my patch on > this patch. Which tree should I base? Which tree should I base the patch on? Best Regards, Huang Ying -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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