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bpf: Use rcu_trace_implies_rcu_gp() for program array freeing

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To support both sleepable and normal uprobe bpf program, the freeing of
trace program array chains a RCU-tasks-trace grace period and a normal
RCU grace period one after the other.

With the introduction of rcu_trace_implies_rcu_gp(),
__bpf_prog_array_free_sleepable_cb() 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, it is safe to invoke kfree() directly.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20221014113946.965131-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2022-10-14 19:39:46 +08:00 committed by Alexei Starovoitov
parent d39d1445d3
commit 4835f9ee98
1 changed files with 7 additions and 1 deletions
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8
kernel/bpf/core.c
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@ -2251,8 +2251,14 @@ static void __bpf_prog_array_free_sleepable_cb(struct rcu_head *rcu)
{
struct bpf_prog_array *progs;
/* If RCU Tasks Trace grace period implies RCU grace period, there is
* no need to call kfree_rcu(), just call kfree() directly.
*/
progs = container_of(rcu, struct bpf_prog_array, rcu);
kfree_rcu(progs, rcu);
if (rcu_trace_implies_rcu_gp())
kfree(progs);
else
kfree_rcu(progs, rcu);
}
void bpf_prog_array_free_sleepable(struct bpf_prog_array *progs)