linux-kernel - [PATCH 01/14] objpool: rework objpool

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Message-ID: <20241228184949.31582-2-yury.norov@gmail.com>
Date: Sat, 28 Dec 2024 10:49:33 -0800
From: Yury Norov <yury.norov@...il.com>
To: linux-kernel@...r.kernel.org,
	Matt Wu <wuqiang.matt@...edance.com>
Cc: Yury Norov <yury.norov@...il.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [PATCH 01/14] objpool: rework objpool_pop()

The function has to track number of iterations to prevent an infinite
loop. for_each_cpu_wrap() macro takes care of it, which simplifies user
code.

Similarly to for_each_possible_cpu() flavor, this patch introduces
for_each_possible_cpu_wrap() version of iterator to keep usage of the
API simple and coherent.

Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 include/linux/cpumask.h | 6 ++++++
 include/linux/objpool.h | 7 +++----
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 9278a50d514f..5cf69a110c1c 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -1033,11 +1033,17 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
 #define for_each_possible_cpu(cpu)	for ((cpu) = 0; (cpu) < 1; (cpu)++)
 #define for_each_online_cpu(cpu)	for ((cpu) = 0; (cpu) < 1; (cpu)++)
 #define for_each_present_cpu(cpu)	for ((cpu) = 0; (cpu) < 1; (cpu)++)
+
+#define for_each_possible_cpu_wrap(cpu, start)	\
+	for ((void)(start), (cpu) = 0; (cpu) < 1; (cpu)++)
 #else
 #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask)
 #define for_each_online_cpu(cpu)   for_each_cpu((cpu), cpu_online_mask)
 #define for_each_enabled_cpu(cpu)   for_each_cpu((cpu), cpu_enabled_mask)
 #define for_each_present_cpu(cpu)  for_each_cpu((cpu), cpu_present_mask)
+
+#define for_each_possible_cpu_wrap(cpu, start)	\
+	for_each_cpu_wrap((cpu), cpu_possible_mask, (start))
 #endif
 
 /* Wrappers for arch boot code to manipulate normally-constant masks */
diff --git a/include/linux/objpool.h b/include/linux/objpool.h
index cb1758eaa2d3..b713a1fe7521 100644
--- a/include/linux/objpool.h
+++ b/include/linux/objpool.h
@@ -170,17 +170,16 @@ static inline void *objpool_pop(struct objpool_head *pool)
 {
 	void *obj = NULL;
 	unsigned long flags;
-	int i, cpu;
+	int start, cpu;
 
 	/* disable local irq to avoid preemption & interruption */
 	raw_local_irq_save(flags);
 
-	cpu = raw_smp_processor_id();
-	for (i = 0; i < pool->nr_possible_cpus; i++) {
+	start = raw_smp_processor_id();
+	for_each_possible_cpu_wrap(cpu, start) {
 		obj = __objpool_try_get_slot(pool, cpu);
 		if (obj)
 			break;
-		cpu = cpumask_next_wrap(cpu, cpu_possible_mask, -1, 1);
 	}
 	raw_local_irq_restore(flags);
 
-- 
2.43.0