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[PATCH 4.4 01/16] powerpc/eeh: Fix deadlock when PE frozen state cant be cleared

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  [PATCH 4.4 01/16] powerpc/eeh: Fix deadlock when PE frozen state cant be cleared Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-12-13 18:20 +0100
    Re: [PATCH 4.4 01/16] powerpc/eeh: Fix deadlock when PE frozen state  cant be cleared Andrew Donnellan <andrew.donnellan@au1.ibm.com> - 2016-12-14 01:10 +0100
      Re: [PATCH 4.4 01/16] powerpc/eeh: Fix deadlock when PE frozen state  cant be cleared Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-12-14 02:10 +0100

#1541294 — [PATCH 4.4 01/16] powerpc/eeh: Fix deadlock when PE frozen state cant be cleared

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andrew Donnellan <andrew.donnellan@au1.ibm.com>

commit 409bf7f8a02ef88db5a0f2cdcf9489914f4b8508 upstream.

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")
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/powerpc/kernel/eeh_driver.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -612,8 +612,10 @@ static int eeh_reset_device(struct eeh_p
 
 	/* 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,

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#1541583 — Re: [PATCH 4.4 01/16] powerpc/eeh: Fix deadlock when PE frozen state cant be cleared

On 14/12/16 04:15, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
>
> ------------------
>
> From: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
>
> commit 409bf7f8a02ef88db5a0f2cdcf9489914f4b8508 upstream.
>
> 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")
> Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
> Acked-by: Russell Currey <ruscur@russell.cc>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

It seems that something in your scripts munged the apostrophe in the 
summary line when generating these emails. Though it looks fine in the 
actual tree.


Andrew

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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#1541626 — Re: [PATCH 4.4 01/16] powerpc/eeh: Fix deadlock when PE frozen state cant be cleared

On Wed, Dec 14, 2016 at 10:59:32AM +1100, Andrew Donnellan wrote:
> On 14/12/16 04:15, Greg Kroah-Hartman wrote:
> > 4.4-stable review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
> > 
> > commit 409bf7f8a02ef88db5a0f2cdcf9489914f4b8508 upstream.
> > 
> > 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")
> > Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
> > Acked-by: Russell Currey <ruscur@russell.cc>
> > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> It seems that something in your scripts munged the apostrophe in the summary
> line when generating these emails. Though it looks fine in the actual tree.

Odd, the original patch has the subject right, so git will do it
correctly when it commits the patch.  But, something dropped the '
character when the email was created.  Given that it goes through quilt
a few different ways to get here to the mailing list, I'll blame it :)

thanks,

greg k-h

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