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bpf: Use rcu_trace_implies_rcu_gp() in bpf memory allocator

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The memory free logic in bpf memory allocator chains a RCU Tasks Trace
grace period and a normal RCU grace period one after the other, so it
can ensure that both sleepable and non-sleepable programs have finished.

With the introduction of rcu_trace_implies_rcu_gp(),
__free_rcu_tasks_trace() can check whether or not a normal RCU grace
period has also passed after a RCU Tasks Trace grace period has passed.
If it is true, freeing these elements directly, else freeing through
call_rcu().

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20221014113946.965131-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2022-10-14 19:39:44 +08:00 committed by Alexei Starovoitov
parent e6c86c513f
commit 59be91e5e7
1 changed files with 10 additions and 5 deletions
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15
kernel/bpf/memalloc.c
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@ -222,9 +222,13 @@ static void __free_rcu(struct rcu_head *head)
static void __free_rcu_tasks_trace(struct rcu_head *head)
{
struct bpf_mem_cache *c = container_of(head, struct bpf_mem_cache, rcu);
call_rcu(&c->rcu, __free_rcu);
/* If RCU Tasks Trace grace period implies RCU grace period,
* there is no need to invoke call_rcu().
*/
if (rcu_trace_implies_rcu_gp())
__free_rcu(head);
else
call_rcu(head, __free_rcu);
}
static void enque_to_free(struct bpf_mem_cache *c, void *obj)
@ -253,8 +257,9 @@ static void do_call_rcu(struct bpf_mem_cache *c)
*/
__llist_add(llnode, &c->waiting_for_gp);
/* Use call_rcu_tasks_trace() to wait for sleepable progs to finish.
* Then use call_rcu() to wait for normal progs to finish
* and finally do free_one() on each element.
* If RCU Tasks Trace grace period implies RCU grace period, free
* these elements directly, else use call_rcu() to wait for normal
* progs to finish and finally do free_one() on each element.
*/
call_rcu_tasks_trace(&c->rcu, __free_rcu_tasks_trace);
}