In the percpu freelist code, it is a common pattern to iterate over the possible CPUs mask starting with the current CPU. The pattern is implemented using a hand rolled while loop with the loop variable increment being open-coded. Simplify the code by using for_each_cpu_wrap() helper to iterate over the possible cpus starting with the current CPU. As a result, some of the special-casing in the loop also gets simplified. No functional change intended. Signed-off-by: Punit Agrawal <punit.agrawal@xxxxxxxxxxxxx> --- v1 -> v2: * Fixed the incorrect transformation changing semantics of __pcpu_freelist_push_nmi() Previous version - v1: https://lore.kernel.org/all/20220817130807.68279-1-punit.agrawal@xxxxxxxxxxxxx/ kernel/bpf/percpu_freelist.c | 48 ++++++++++++------------------------ 1 file changed, 16 insertions(+), 32 deletions(-) diff --git a/kernel/bpf/percpu_freelist.c b/kernel/bpf/percpu_freelist.c index 00b874c8e889..b6e7f5c5b9ab 100644 --- a/kernel/bpf/percpu_freelist.c +++ b/kernel/bpf/percpu_freelist.c @@ -58,23 +58,21 @@ static inline void ___pcpu_freelist_push_nmi(struct pcpu_freelist *s, { int cpu, orig_cpu; - orig_cpu = cpu = raw_smp_processor_id(); + orig_cpu = raw_smp_processor_id(); while (1) { - struct pcpu_freelist_head *head; + for_each_cpu_wrap(cpu, cpu_possible_mask, orig_cpu) { + struct pcpu_freelist_head *head; - head = per_cpu_ptr(s->freelist, cpu); - if (raw_spin_trylock(&head->lock)) { - pcpu_freelist_push_node(head, node); - raw_spin_unlock(&head->lock); - return; + head = per_cpu_ptr(s->freelist, cpu); + if (raw_spin_trylock(&head->lock)) { + pcpu_freelist_push_node(head, node); + raw_spin_unlock(&head->lock); + return; + } } - cpu = cpumask_next(cpu, cpu_possible_mask); - if (cpu >= nr_cpu_ids) - cpu = 0; /* cannot lock any per cpu lock, try extralist */ - if (cpu == orig_cpu && - pcpu_freelist_try_push_extra(s, node)) + if (pcpu_freelist_try_push_extra(s, node)) return; } } @@ -125,13 +123,12 @@ static struct pcpu_freelist_node *___pcpu_freelist_pop(struct pcpu_freelist *s) { struct pcpu_freelist_head *head; struct pcpu_freelist_node *node; - int orig_cpu, cpu; + int cpu; - orig_cpu = cpu = raw_smp_processor_id(); - while (1) { + for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) { head = per_cpu_ptr(s->freelist, cpu); if (!READ_ONCE(head->first)) - goto next_cpu; + continue; raw_spin_lock(&head->lock); node = head->first; if (node) { @@ -140,12 +137,6 @@ static struct pcpu_freelist_node *___pcpu_freelist_pop(struct pcpu_freelist *s) return node; } raw_spin_unlock(&head->lock); -next_cpu: - cpu = cpumask_next(cpu, cpu_possible_mask); - if (cpu >= nr_cpu_ids) - cpu = 0; - if (cpu == orig_cpu) - break; } /* per cpu lists are all empty, try extralist */ @@ -164,13 +155,12 @@ ___pcpu_freelist_pop_nmi(struct pcpu_freelist *s) { struct pcpu_freelist_head *head; struct pcpu_freelist_node *node; - int orig_cpu, cpu; + int cpu; - orig_cpu = cpu = raw_smp_processor_id(); - while (1) { + for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) { head = per_cpu_ptr(s->freelist, cpu); if (!READ_ONCE(head->first)) - goto next_cpu; + continue; if (raw_spin_trylock(&head->lock)) { node = head->first; if (node) { @@ -180,12 +170,6 @@ ___pcpu_freelist_pop_nmi(struct pcpu_freelist *s) } raw_spin_unlock(&head->lock); } -next_cpu: - cpu = cpumask_next(cpu, cpu_possible_mask); - if (cpu >= nr_cpu_ids) - cpu = 0; - if (cpu == orig_cpu) - break; } /* cannot pop from per cpu lists, try extralist */ -- 2.35.1
