linux-kernel - [PATCH 4.4 007/113] powerpc/eeh: eeh_pci_enable(): fix checking of post-request state

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Date:   Mon,  5 Sep 2016 18:43:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Gavin Shan <gwshan@...ux.vnet.ibm.com>,
        Daniel Axtens <dja@...ens.net>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 4.4 007/113] powerpc/eeh: eeh_pci_enable(): fix checking of post-request state

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

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

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

commit 949e9b827eb4736d96df520c67d07a54c64e99b8 upstream.

In eeh_pci_enable(), after making the request to set the new options, we
call eeh_ops->wait_state() to check that the request finished successfully.

At the moment, if eeh_ops->wait_state() returns 0, we return 0 without
checking that it reflects the expected outcome. This can lead to callers
further up the chain incorrectly assuming the slot has been successfully
unfrozen and continuing to attempt recovery.

On powernv, this will occur if pnv_eeh_get_pe_state() or
pnv_eeh_get_phb_state() return 0, which in turn occurs if the relevant OPAL
call returns OPAL_EEH_STOPPED_MMIO_DMA_FREEZE or
OPAL_EEH_PHB_ERROR respectively.

On pseries, this will occur if pseries_eeh_get_state() returns 0, which in
turn occurs if RTAS reports that the PE is in the MMIO Stopped and DMA
Stopped states.

Obviously, none of these cases represent a successful completion of a
request to thaw MMIO or DMA.

Fix the check so that a wait_state() return value of 0 won't be considered
successful for the EEH_OPT_THAW_MMIO or EEH_OPT_THAW_DMA cases.

Signed-off-by: Andrew Donnellan <andrew.donnellan@....ibm.com>
Acked-by: Gavin Shan <gwshan@...ux.vnet.ibm.com>
Reviewed-by: Daniel Axtens <dja@...ens.net>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/kernel/eeh.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -677,7 +677,7 @@ int eeh_pci_enable(struct eeh_pe *pe, in
 	/* Check if the request is finished successfully */
 	if (active_flag) {
 		rc = eeh_ops->wait_state(pe, PCI_BUS_RESET_WAIT_MSEC);
-		if (rc <= 0)
+		if (rc < 0)
 			return rc;

 		if (rc & active_flag)