Patch "genirq: Prevent resend to interrupts marked IRQ_NESTED_THREAD" has been added to the 3.14-stable tree

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

genirq: Prevent resend to interrupts marked IRQ_NESTED_THREAD

to the 3.14-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:
genirq-prevent-resend-to-interrupts-marked-irq_nested_thread.patch
and it can be found in the queue-3.14 subdirectory.

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

From: Thomas Gleixner <[email protected]>
Date: Thu, 16 Jul 2015 14:10:17 +0200
Subject: genirq: Prevent resend to interrupts marked IRQ_NESTED_THREAD
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From: Thomas Gleixner <[email protected]>

commit 75a06189fc508a2acf470b0b12710362ffb2c4b1 upstream.

The resend mechanism happily calls the interrupt handler of interrupts which are marked IRQ_NESTED_THREAD from softirq context. This can result in crashes because the interrupt handler is not the proper way to invoke the device handlers. They must be invoked via handle_nested_irq.

Prevent the resend even if the interrupt has no valid parent irq set. Its better to have a lost interrupt than a crashing machine.

---
 kernel/irq/resend.c |   18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

@@ -75,13 +75,21 @@ void check_irq_resend(struct irq_desc *d
 		    !desc->irq_data.chip->irq_retrigger(&desc->irq_data)) {
 #ifdef CONFIG_HARDIRQS_SW_RESEND
 			/*
-			 * If the interrupt has a parent irq and runs
-			 * in the thread context of the parent irq,
-			 * retrigger the parent.
+			 * If the interrupt is running in the thread
+			 * context of the parent irq we need to be
+			 * careful, because we cannot trigger it
+			 * directly.
 			 */
-			if (desc->parent_irq &&
-			    irq_settings_is_nested_thread(desc))
+			if (irq_settings_is_nested_thread(desc)) {
+				/*
+				 * If the parent_irq is valid, we
+				 * retrigger the parent, otherwise we
+				 * do nothing.
+				 */
+				if (!desc->parent_irq)
+					return;
 				irq = desc->parent_irq;
+			}
 			/* Set it pending and activate the softirq: */
 			set_bit(irq, irqs_resend);
 			tasklet_schedule(&resend_tasklet);

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

queue-3.14/genirq-prevent-resend-to-interrupts-marked-irq_nested_thread.patch