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bpf: Refactor alloc_bulk(). 

Factor out inner body of alloc_bulk into separate helper.
No functional changes.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20230706033447.54696-5-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2023-07-05 20:34:37 -07:00 committed by Daniel Borkmann
parent 9de3e81521
commit 05ae68656a
1 changed files with 26 additions and 20 deletions
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46
kernel/bpf/memalloc.c
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@ -154,11 +154,35 @@ static struct mem_cgroup *get_memcg(const struct bpf_mem_cache *c)
#endif
}
static void add_obj_to_free_list(struct bpf_mem_cache *c, void *obj)
{
unsigned long flags;
if (IS_ENABLED(CONFIG_PREEMPT_RT))
/* In RT irq_work runs in per-cpu kthread, so disable
* interrupts to avoid preemption and interrupts and
* reduce the chance of bpf prog executing on this cpu
* when active counter is busy.
*/
local_irq_save(flags);
/* alloc_bulk runs from irq_work which will not preempt a bpf
* program that does unit_alloc/unit_free since IRQs are
* disabled there. There is no race to increment 'active'
* counter. It protects free_llist from corruption in case NMI
* bpf prog preempted this loop.
*/
WARN_ON_ONCE(local_inc_return(&c->active) != 1);
__llist_add(obj, &c->free_llist);
c->free_cnt++;
local_dec(&c->active);
if (IS_ENABLED(CONFIG_PREEMPT_RT))
local_irq_restore(flags);
}
/* Mostly runs from irq_work except __init phase. */
static void alloc_bulk(struct bpf_mem_cache *c, int cnt, int node)
{
struct mem_cgroup *memcg = NULL, *old_memcg;
unsigned long flags;
void *obj;
int i;
@ -188,25 +212,7 @@ static void alloc_bulk(struct bpf_mem_cache *c, int cnt, int node)
if (!obj)
break;
}
if (IS_ENABLED(CONFIG_PREEMPT_RT))
/* In RT irq_work runs in per-cpu kthread, so disable
* interrupts to avoid preemption and interrupts and
* reduce the chance of bpf prog executing on this cpu
* when active counter is busy.
*/
local_irq_save(flags);
/* alloc_bulk runs from irq_work which will not preempt a bpf
* program that does unit_alloc/unit_free since IRQs are
* disabled there. There is no race to increment 'active'
* counter. It protects free_llist from corruption in case NMI
* bpf prog preempted this loop.
*/
WARN_ON_ONCE(local_inc_return(&c->active) != 1);
__llist_add(obj, &c->free_llist);
c->free_cnt++;
local_dec(&c->active);
if (IS_ENABLED(CONFIG_PREEMPT_RT))
local_irq_restore(flags);
add_obj_to_free_list(c, obj);
}
set_active_memcg(old_memcg);
mem_cgroup_put(memcg);