linux-kernel - [PATCH v1 1/1] irqdomain: Check virq for 0 before use in irq_dispose

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Message-Id: <20230822135136.2138380-1-andriy.shevchenko@linux.intel.com>
Date:   Tue, 22 Aug 2023 16:51:36 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Marc Zyngier <maz@...nel.org>,
        Johan Hovold <johan+linaro@...nel.org>,
        linux-kernel@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v1 1/1] irqdomain: Check virq for 0 before use in irq_dispose_mapping()

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

This, in particular, should clearly answer the question whether caller
need to perform this check or not, and we have plenty 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>
---
 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 0bdef4fe925b..26f1be63d622 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -903,10 +903,11 @@ 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;
-- 
2.40.0.1.gaa8946217a0b