* [PATCH] powerpc/eeh: fix deadlock when PE frozen state can't be cleared
@ 2016-12-01 0:23 Andrew Donnellan
2016-12-01 0:27 ` Russell Currey
2016-12-03 11:31 ` Michael Ellerman
0 siblings, 2 replies; 3+ messages in thread
From: Andrew Donnellan @ 2016-12-01 0:23 UTC (permalink / raw)
To: linuxppc-dev, ruscur, gwshan; +Cc: ukrishn, pradghos
In eeh_reset_device(), we take the pci_rescan_remove_lock immediately after
after we call eeh_reset_pe() to reset the PCI controller. We then call
eeh_clear_pe_frozen_state(), which can return an error. In this case, we
bail out of eeh_reset_device() without calling pci_unlock_rescan_remove().
Add a call to pci_unlock_rescan_remove() in the eeh_clear_pe_frozen_state()
error path so that we don't cause a deadlock later on.
Reported-by: Pradipta Ghosh <pradghos@in.ibm.com>
Fixes: 78954700631f ("powerpc/eeh: Avoid I/O access during PE reset")
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
---
arch/powerpc/kernel/eeh_driver.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index a62be72..5c31369 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -671,8 +671,10 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus,
/* Clear frozen state */
rc = eeh_clear_pe_frozen_state(pe, false);
- if (rc)
+ if (rc) {
+ pci_unlock_rescan_remove();
return rc;
+ }
/* Give the system 5 seconds to finish running the user-space
* hotplug shutdown scripts, e.g. ifdown for ethernet. Yes,
--
Andrew Donnellan OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com IBM Australia Limited
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] powerpc/eeh: fix deadlock when PE frozen state can't be cleared
2016-12-01 0:23 [PATCH] powerpc/eeh: fix deadlock when PE frozen state can't be cleared Andrew Donnellan
@ 2016-12-01 0:27 ` Russell Currey
2016-12-03 11:31 ` Michael Ellerman
1 sibling, 0 replies; 3+ messages in thread
From: Russell Currey @ 2016-12-01 0:27 UTC (permalink / raw)
To: Andrew Donnellan, linuxppc-dev, gwshan; +Cc: ukrishn, pradghos
On Thu, 2016-12-01 at 11:23 +1100, Andrew Donnellan wrote:
> In eeh_reset_device(), we take the pci_rescan_remove_lock immediately after
> after we call eeh_reset_pe() to reset the PCI controller. We then call
> eeh_clear_pe_frozen_state(), which can return an error. In this case, we
> bail out of eeh_reset_device() without calling pci_unlock_rescan_remove().
>
> Add a call to pci_unlock_rescan_remove() in the eeh_clear_pe_frozen_state()
> error path so that we don't cause a deadlock later on.
>
> Reported-by: Pradipta Ghosh <pradghos@in.ibm.com>
> Fixes: 78954700631f ("powerpc/eeh: Avoid I/O access during PE reset")
> Cc: stable@vger.kernel.org
> Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
> ---
Locking in this function is such a mess, we (I) should revisit it at some point.
Acked-by: Russell Currey <ruscur@russell.cc>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: powerpc/eeh: fix deadlock when PE frozen state can't be cleared
2016-12-01 0:23 [PATCH] powerpc/eeh: fix deadlock when PE frozen state can't be cleared Andrew Donnellan
2016-12-01 0:27 ` Russell Currey
@ 2016-12-03 11:31 ` Michael Ellerman
1 sibling, 0 replies; 3+ messages in thread
From: Michael Ellerman @ 2016-12-03 11:31 UTC (permalink / raw)
To: Andrew Donnellan, linuxppc-dev, ruscur, gwshan; +Cc: pradghos, ukrishn
On Thu, 2016-12-01 at 00:23:05 UTC, Andrew Donnellan wrote:
> In eeh_reset_device(), we take the pci_rescan_remove_lock immediately after
> after we call eeh_reset_pe() to reset the PCI controller. We then call
> eeh_clear_pe_frozen_state(), which can return an error. In this case, we
> bail out of eeh_reset_device() without calling pci_unlock_rescan_remove().
>
> Add a call to pci_unlock_rescan_remove() in the eeh_clear_pe_frozen_state()
> error path so that we don't cause a deadlock later on.
>
> Reported-by: Pradipta Ghosh <pradghos@in.ibm.com>
> Fixes: 78954700631f ("powerpc/eeh: Avoid I/O access during PE reset")
> Cc: stable@vger.kernel.org
> Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
> Acked-by: Russell Currey <ruscur@russell.cc>
Applied to powerpc fixes, thanks.
https://git.kernel.org/powerpc/c/409bf7f8a02ef88db5a0f2cdcf9489
cheers
^ permalink raw reply [flat|nested] 3+ messages in thread
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