linux-kernel - [tip: irq/core] irqdomain: Check virq for 0 before use in irq_dispose

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Date: Mon, 08 Apr 2024 10:18:00 -0000
From: "tip-bot2 for Andy Shevchenko" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org, maz@...nel.org
Subject: [tip: irq/core] irqdomain: Check virq for 0 before use in
 irq_dispose_mapping()

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     a2ea3cd78317ae8995b65b52299158bbae52a77f
Gitweb:        https://git.kernel.org/tip/a2ea3cd78317ae8995b65b52299158bbae52a77f
Author:        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
AuthorDate:    Fri, 05 Apr 2024 22:01:05 +03:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Mon, 08 Apr 2024 12:08:58 +02:00

irqdomain: Check virq for 0 before use in irq_dispose_mapping()

It's a bit hard to read the logic since the virq is used before checking it
for 0. Rearrange the code to make it better to understand.

This, in particular, should clearly answer the question whether the caller
needs to perform this check or not, and there are plenty of places for both
variants, confirming a confusion.

Fun fact that the new code is shorter:

  Function                                     old     new   delta
  irq_dispose_mapping                          278     271      -7
  Total: Before=11625, After=11618, chg -0.06%

when compiled by GCC on Debian for x86_64.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://lore.kernel.org/r/20240405190105.3932034-1-andriy.shevchenko@linux.intel.com

---
 kernel/irq/irqdomain.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 3dd1c87..aadc889 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -909,10 +909,11 @@ EXPORT_SYMBOL_GPL(irq_create_of_mapping);
  */
 void irq_dispose_mapping(unsigned int virq)
 {
-	struct irq_data *irq_data = irq_get_irq_data(virq);
+	struct irq_data *irq_data;
 	struct irq_domain *domain;
 
-	if (!virq || !irq_data)
+	irq_data = virq ? irq_get_irq_data(virq) : NULL;
+	if (!irq_data)
 		return;
 
 	domain = irq_data->domain;