Patch "x86/irq: Reorganize the search in assign_irq_vector" 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

    x86/irq: Reorganize the search in assign_irq_vector

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:
     x86-irq-reorganize-the-search-in-assign_irq_vector.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 95ffeb4b5baca266e1d0d2bc90f1513e6f419cdd Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 31 Dec 2015 16:30:47 +0000
Subject: x86/irq: Reorganize the search in assign_irq_vector

From: Thomas Gleixner <tglx@linutronix.de>

commit 95ffeb4b5baca266e1d0d2bc90f1513e6f419cdd upstream.

Split out the code which advances the target cpu for the search so we can
reuse it for the next patch which adds an early validation check for the
vectormask which we get from the apic.

Add comments while at it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Borislav Petkov <bp@alien8.de>
Tested-by: Joe Lawrence <joe.lawrence@stratus.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jeremiah Mahler <jmmahler@gmail.com>
Cc: andy.shevchenko@gmail.com
Cc: Guenter Roeck <linux@roeck-us.net>
Link: http://lkml.kernel.org/r/20151231160106.484562040@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/apic/vector.c |   24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -155,14 +155,9 @@ next:
 			vector = FIRST_EXTERNAL_VECTOR + offset;
 		}
 
-		if (unlikely(current_vector == vector)) {
-			cpumask_or(searched_cpumask, searched_cpumask,
-				   vector_cpumask);
-			cpumask_andnot(vector_cpumask, mask, searched_cpumask);
-			cpu = cpumask_first_and(vector_cpumask,
-						cpu_online_mask);
-			continue;
-		}
+		/* If the search wrapped around, try the next cpu */
+		if (unlikely(current_vector == vector))
+			goto next_cpu;
 
 		if (test_bit(vector, used_vectors))
 			goto next;
@@ -184,6 +179,19 @@ next:
 		d->cfg.vector = vector;
 		cpumask_copy(d->domain, vector_cpumask);
 		goto success;
+
+next_cpu:
+		/*
+		 * We exclude the current @vector_cpumask from the requested
+		 * @mask and try again with the next online cpu in the
+		 * result. We cannot modify @mask, so we use @vector_cpumask
+		 * as a temporary buffer here as it will be reassigned when
+		 * calling apic->vector_allocation_domain() above.
+		 */
+		cpumask_or(searched_cpumask, searched_cpumask, vector_cpumask);
+		cpumask_andnot(vector_cpumask, mask, searched_cpumask);
+		cpu = cpumask_first_and(vector_cpumask, cpu_online_mask);
+		continue;
 	}
 	return -ENOSPC;
 


Patches currently in stable-queue which might be from tglx@linutronix.de are

queue-4.4/x86-irq-validate-that-irq-descriptor-is-still-active.patch
queue-4.4/x86-irq-remove-outgoing-cpu-from-vector-cleanup-mask.patch
queue-4.4/x86-irq-get-rid-of-code-duplication.patch
queue-4.4/x86-entry-compat-add-missing-clac-to-entry_int80_32.patch
queue-4.4/tick-nohz-set-the-correct-expiry-when-switching-to-nohz-lowres-mode.patch
queue-4.4/irqchip-mxs-add-missing-set_handle_irq.patch
queue-4.4/genirq-validate-action-before-dereferencing-it-in-handle_irq_event_percpu.patch
queue-4.4/x86-irq-remove-offline-cpus-from-vector-cleanup.patch
queue-4.4/posix-clock-fix-return-code-on-the-poll-method-s-error-path.patch
queue-4.4/x86-irq-reorganize-the-return-path-in-assign_irq_vector.patch
queue-4.4/cputime-prevent-32bit-overflow-in-time_to_cputime.patch
queue-4.4/x86-irq-copy-vectormask-instead-of-an-and-operation.patch
queue-4.4/x86-irq-call-irq_force_move_complete-with-irq-descriptor.patch
queue-4.4/x86-irq-call-chip-irq_set_affinity-in-proper-context.patch
queue-4.4/x86-irq-plug-vector-cleanup-race.patch
queue-4.4/x86-irq-do-not-use-apic_chip_data.old_domain-as-temporary-buffer.patch
queue-4.4/clockevents-tcb_clksrc-prevent-disabling-an-already-disabled-clock.patch
queue-4.4/x86-irq-reorganize-the-search-in-assign_irq_vector.patch
queue-4.4/x86-irq-remove-the-cpumask-allocation-from-send_cleanup_vector.patch
queue-4.4/x86-irq-fix-a-race-in-x86_vector_free_irqs.patch
queue-4.4/x86-irq-check-vector-allocation-early.patch
queue-4.4/irqchip-omap-intc-add-support-for-spurious-irq-handling.patch
queue-4.4/x86-irq-clear-move_in_progress-before-sending-cleanup-ipi.patch
queue-4.4/x86-mpx-fix-off-by-one-comparison-with-nr_registers.patch
queue-4.4/irqchip-atmel-aic-fix-wrong-bit-operation-for-irq-priority.patch
queue-4.4/revert-workqueue-make-sure-delayed-work-run-in-local-cpu.patch