Patch "scsi: cxlflash: Improve EEH recovery time" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    scsi: cxlflash: Improve EEH recovery time

to the 4.4-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:
     scsi-cxlflash-improve-eeh-recovery-time.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 05dab43230fdc0d14ca885b473a2740fe017ecb1 Mon Sep 17 00:00:00 2001
From: "Matthew R. Ochs" <mrochs@linux.vnet.ibm.com>
Date: Fri, 2 Sep 2016 15:40:03 -0500
Subject: scsi: cxlflash: Improve EEH recovery time

From: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>

commit 05dab43230fdc0d14ca885b473a2740fe017ecb1 upstream.

When an EEH occurs during device initialization, the port timeout logic
can cause excessive delays as MMIO reads will fail. Depending on where
they are experienced, these delays can lead to a prolonged reset,
causing an unnecessary triggering of other timeout logic in the SCSI
stack or user applications.

To expedite recovery, the port timeout logic is updated to decay the
timeout at a much faster rate when in the presence of a likely EEH
frozen event.

Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Acked-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/scsi/cxlflash/main.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/scsi/cxlflash/main.c
+++ b/drivers/scsi/cxlflash/main.c
@@ -996,6 +996,8 @@ static int wait_port_online(__be64 __iom
 	do {
 		msleep(delay_us / 1000);
 		status = readq_be(&fc_regs[FC_MTIP_STATUS / 8]);
+		if (status == U64_MAX)
+			nretry /= 2;
 	} while ((status & FC_MTIP_STATUS_MASK) != FC_MTIP_STATUS_ONLINE &&
 		 nretry--);
 
@@ -1027,6 +1029,8 @@ static int wait_port_offline(__be64 __io
 	do {
 		msleep(delay_us / 1000);
 		status = readq_be(&fc_regs[FC_MTIP_STATUS / 8]);
+		if (status == U64_MAX)
+			nretry /= 2;
 	} while ((status & FC_MTIP_STATUS_MASK) != FC_MTIP_STATUS_OFFLINE &&
 		 nretry--);
 


Patches currently in stable-queue which might be from mrochs@linux.vnet.ibm.com are

queue-4.4/scsi-cxlflash-fix-to-avoid-eeh-and-host-reset-collisions.patch
queue-4.4/scsi-cxlflash-scan-host-only-after-the-port-is-ready-for-i-o.patch
queue-4.4/scsi-cxlflash-improve-eeh-recovery-time.patch