Patch "cxl: Keep IRQ mappings on context teardown" has been added to the 4.4-stable tree

Patch "cxl: Keep IRQ mappings on context teardown" has been added to the 4.4-stable tree

[gregkh]

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

    cxl: Keep IRQ mappings on context teardown

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:
     cxl-keep-irq-mappings-on-context-teardown.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 d6776bba44d9752f6cdf640046070e71ee4bba7b Mon Sep 17 00:00:00 2001
From: Michael Neuling <mikey@neuling.org>
Date: Fri, 22 Apr 2016 14:57:48 +1000
Subject: cxl: Keep IRQ mappings on context teardown

From: Michael Neuling <mikey@neuling.org>

commit d6776bba44d9752f6cdf640046070e71ee4bba7b upstream.

Keep IRQ mappings on context teardown.  This won't leak IRQs as if we
allocate the mapping again, the generic code will give the same
mapping used last time.

Doing this works around a race in the generic code. Masking the
interrupt introduces a race which can crash the kernel or result in
IRQ that is never EOIed. The lost of EOI results in all subsequent
mappings to the same HW IRQ never receiving an interrupt.

We've seen this race with cxl test cases which are doing heavy context
startup and teardown at the same time as heavy interrupt load.

A fix to the generic code is being investigated also.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Tested-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Tested-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/misc/cxl/irq.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/misc/cxl/irq.c
+++ b/drivers/misc/cxl/irq.c
@@ -288,7 +288,6 @@ unsigned int cxl_map_irq(struct cxl *ada
 void cxl_unmap_irq(unsigned int virq, void *cookie)
 {
 	free_irq(virq, cookie);
-	irq_dispose_mapping(virq);
 }
 
 static int cxl_register_one_irq(struct cxl *adapter,


Patches currently in stable-queue which might be from mikey@neuling.org are

queue-4.4/cxl-keep-irq-mappings-on-context-teardown.patch