linux-kernel - [PATCH 4.4 326/342] x86/irq: Reorganize the return path in assign_irq

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Message-Id: <20160301234538.398452249@linuxfoundation.org>
Date:	Tue, 01 Mar 2016 23:55:41 +0000
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	<linux-kernel@...r.kernel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<stable@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Joe Lawrence <joe.lawrence@...atus.com>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Jeremiah Mahler <jmmahler@...il.com>,
	<andy.shevchenko@...il.com>, Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 4.4 326/342] x86/irq: Reorganize the return path in assign_irq_vector

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Gleixner <tglx@...utronix.de>

commit 433cbd57d190a1cdd02f243df41c3d7f55ec4b94 upstream.

Use an explicit goto for the cases where we have success in the search/update
and return -ENOSPC if the search loop ends due to no space.

Preparatory patch for fixes. No functional change.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Borislav Petkov <bp@...en8.de>
Tested-by: Joe Lawrence <joe.lawrence@...atus.com>
Cc: Jiang Liu <jiang.liu@...ux.intel.com>
Cc: Jeremiah Mahler <jmmahler@...il.com>
Cc: andy.shevchenko@...il.com
Cc: Guenter Roeck <linux@...ck-us.net>
Link: http://lkml.kernel.org/r/20151231160106.403491024@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/kernel/apic/vector.c |   22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -116,13 +116,12 @@ static int __assign_irq_vector(int irq,
 	 */
 	static int current_vector = FIRST_EXTERNAL_VECTOR + VECTOR_OFFSET_START;
 	static int current_offset = VECTOR_OFFSET_START % 16;
-	int cpu, err;
+	int cpu;
 
 	if (d->move_in_progress)
 		return -EBUSY;
 
 	/* Only try and allocate irqs on cpus that are present */
-	err = -ENOSPC;
 	cpumask_clear(d->old_domain);
 	cpumask_clear(searched_cpumask);
 	cpu = cpumask_first_and(mask, cpu_online_mask);
@@ -132,9 +131,8 @@ static int __assign_irq_vector(int irq,
 		apic->vector_allocation_domain(cpu, vector_cpumask, mask);
 
 		if (cpumask_subset(vector_cpumask, d->domain)) {
-			err = 0;
 			if (cpumask_equal(vector_cpumask, d->domain))
-				break;
+				goto success;
 			/*
 			 * New cpumask using the vector is a proper subset of
 			 * the current in use mask. So cleanup the vector
@@ -145,7 +143,7 @@ static int __assign_irq_vector(int irq,
 			d->move_in_progress =
 			   cpumask_intersects(d->old_domain, cpu_online_mask);
 			cpumask_and(d->domain, d->domain, vector_cpumask);
-			break;
+			goto success;
 		}
 
 		vector = current_vector;
@@ -185,17 +183,13 @@ next:
 			per_cpu(vector_irq, new_cpu)[vector] = irq_to_desc(irq);
 		d->cfg.vector = vector;
 		cpumask_copy(d->domain, vector_cpumask);
-		err = 0;
-		break;
+		goto success;
 	}
+	return -ENOSPC;
 
-	if (!err) {
-		/* cache destination APIC IDs into cfg->dest_apicid */
-		err = apic->cpu_mask_to_apicid_and(mask, d->domain,
-						   &d->cfg.dest_apicid);
-	}
-
-	return err;
+success:
+	/* cache destination APIC IDs into cfg->dest_apicid */
+	return apic->cpu_mask_to_apicid_and(mask, d->domain, &d->cfg.dest_apicid);
 }
 
 static int assign_irq_vector(int irq, struct apic_chip_data *data,