Patch "PCI: pciehp: Report power fault only once until we clear it" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

PCI: pciehp: Report power fault only once until we clear it

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
pci-pciehp-report-power-fault-only-once-until-we-clear-it.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Keith Busch <[email protected]>
Date: Tue, 1 Aug 2017 03:11:52 -0400
Subject: PCI: pciehp: Report power fault only once until we clear it

From: Keith Busch <[email protected]>

commit 7612b3b28c0b900dcbcdf5e9b9747cc20a1e2455 upstream.

When a power fault occurs, the power controller sets Power Fault Detected in the Slot Status register, and pciehp_isr() queues an INT_POWER_FAULT event to handle it.

It also clears Power Fault Detected, but since nothing has yet changed to correct the power fault, the power controller will likely set it again immediately, which may cause an infinite loop when pcie_isr() rechecks Slot Status.

Fix that by masking off Power Fault Detected from new events if the driver hasn't seen the power fault clear from the previous handling attempt.

---
 drivers/pci/hotplug/pciehp_hpc.c |    8 ++++++++
 1 file changed, 8 insertions(+)

@@ -586,6 +586,14 @@ static irqreturn_t pciehp_isr(int irq, v
 	events = status & (PCI_EXP_SLTSTA_ABP | PCI_EXP_SLTSTA_PFD |
 			   PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_CC |
 			   PCI_EXP_SLTSTA_DLLSC);
+
+	/*
+	 * If we've already reported a power fault, don't report it again
+	 * until we've done something to handle it.
+	 */
+	if (ctrl->power_fault_detected)
+		events &= ~PCI_EXP_SLTSTA_PFD;
+
 	if (!events)
 		return IRQ_NONE;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/pci-pciehp-report-power-fault-only-once-until-we-clear-it.patch