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bpf: Simplify code by using for_each_cpu_wrap()

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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@bytedance.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20220907155746.1750329-1-punit.agrawal@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Punit Agrawal 2022-09-07 16:57:46 +01:00 committed by Alexei Starovoitov
parent cf7de6a536
commit 57c92f11a2
1 changed files with 16 additions and 32 deletions
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48
kernel/bpf/percpu_freelist.c
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@ -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 */