linux-kernel - [PATCH v2 1/4] cpumask: relax cpumask_any

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Message-ID: <20250427185242.221974-2-yury.norov@gmail.com>
Date: Sun, 27 Apr 2025 14:52:28 -0400
From: Yury Norov <yury.norov@...il.com>
To: Reinette Chatre <reinette.chatre@...el.com>,
	James Morse <james.morse@....com>
Cc: "Yury Norov [NVIDIA]" <yury.norov@...il.com>,
	Tony Luck <tony.luck@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/4] cpumask: relax cpumask_any_but()

From: "Yury Norov [NVIDIA]" <yury.norov@...il.com>

Similarly to other cpumask search functions, accept -1, and consider
it as 'any cpu' hint. This helps users to avoid coding special cases.

Tested-by: James Morse <james.morse@....com>
Reviewed-by: James Morse <james.morse@....com>
Signed-off-by: Yury Norov [NVIDIA] <yury.norov@...il.com>
---
 include/linux/cpumask.h | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index beff4d26e605..0c57b9892d80 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -413,14 +413,18 @@ unsigned int cpumask_next_wrap(int n, const struct cpumask *src)
  * @cpu: the cpu to ignore.
  *
  * Often used to find any cpu but smp_processor_id() in a mask.
+ * If @cpu == -1, the function is equivalent to cpumask_any().
  * Return: >= nr_cpu_ids if no cpus set.
  */
 static __always_inline
-unsigned int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
+unsigned int cpumask_any_but(const struct cpumask *mask, int cpu)
 {
 	unsigned int i;
 
-	cpumask_check(cpu);
+	/* -1 is a legal arg here. */
+	if (cpu != -1)
+		cpumask_check(cpu);
+
 	for_each_cpu(i, mask)
 		if (i != cpu)
 			break;
@@ -433,16 +437,20 @@ unsigned int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
  * @mask2: the second input cpumask
  * @cpu: the cpu to ignore
  *
+ * If @cpu == -1, the function is equivalent to cpumask_any_and().
  * Returns >= nr_cpu_ids if no cpus set.
  */
 static __always_inline
 unsigned int cpumask_any_and_but(const struct cpumask *mask1,
 				 const struct cpumask *mask2,
-				 unsigned int cpu)
+				 int cpu)
 {
 	unsigned int i;
 
-	cpumask_check(cpu);
+	/* -1 is a legal arg here. */
+	if (cpu != -1)
+		cpumask_check(cpu);
+
 	i = cpumask_first_and(mask1, mask2);
 	if (i != cpu)
 		return i;
-- 
2.43.0