This is a note to let you know that I've just added the patch titled
genirq: Always force thread affinity
to the 3.0-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-always-force-thread-affinity.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 04aa530ec04f61875b99c12721162e2964e3318c Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <[email protected]>
Date: Sat, 3 Nov 2012 11:52:09 +0100
Subject: genirq: Always force thread affinity
From: Thomas Gleixner <[email protected]>
commit 04aa530ec04f61875b99c12721162e2964e3318c upstream.
Sankara reported that the genirq core code fails to adjust the
affinity of an interrupt thread in several cases:
1) On request/setup_irq() the call to setup_affinity() happens before
the new action is registered, so the new thread is not notified.
2) For secondary shared interrupts nothing notifies the new thread to
change its affinity.
3) Interrupts which have the IRQ_NO_BALANCE flag set are not moving
the thread either.
Fix this by setting the thread affinity flag right on thread creation
time. This ensures that under all circumstances the thread moves to
the right place. Requires a check in irq_thread_check_affinity for an
existing affinity mask (CONFIG_CPU_MASK_OFFSTACK=y)
Reported-and-tested-by: Sankara Muthukrishnan <[email protected]>
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1209041738200.2754@ionos
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/irq/manage.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -698,6 +698,7 @@ static void
irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
{
cpumask_var_t mask;
+ bool valid = true;
if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
return;
@@ -712,10 +713,18 @@ irq_thread_check_affinity(struct irq_des
}
raw_spin_lock_irq(&desc->lock);
- cpumask_copy(mask, desc->irq_data.affinity);
+ /*
+ * This code is triggered unconditionally. Check the affinity
+ * mask pointer. For CPU_MASK_OFFSTACK=n this is optimized out.
+ */
+ if (desc->irq_data.affinity)
+ cpumask_copy(mask, desc->irq_data.affinity);
+ else
+ valid = false;
raw_spin_unlock_irq(&desc->lock);
- set_cpus_allowed_ptr(current, mask);
+ if (valid)
+ set_cpus_allowed_ptr(current, mask);
free_cpumask_var(mask);
}
#else
@@ -925,6 +934,16 @@ __setup_irq(unsigned int irq, struct irq
*/
get_task_struct(t);
new->thread = t;
+ /*
+ * Tell the thread to set its affinity. This is
+ * important for shared interrupt handlers as we do
+ * not invoke setup_affinity() for the secondary
+ * handlers as everything is already set up. Even for
+ * interrupts marked with IRQF_NO_BALANCE this is
+ * correct as we want the thread to move to the cpu(s)
+ * on which the requesting code placed the interrupt.
+ */
+ set_bit(IRQTF_AFFINITY, &new->thread_flags);
}
if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/genirq-always-force-thread-affinity.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
