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bpf: Use rcu_trace_implies_rcu_gp() in local storage map

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Local storage map is accessible for both sleepable and non-sleepable bpf
program, and its memory is freed by using both call_rcu_tasks_trace() and
kfree_rcu() to wait for both RCU-tasks-trace grace period and RCU grace
period to pass.

With the introduction of rcu_trace_implies_rcu_gp(), both
bpf_selem_free_rcu() and bpf_local_storage_free_rcu() 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 call kfree()
directly.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20221014113946.965131-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Hou Tao 2022-10-14 19:39:45 +08:00 committed by Alexei Starovoitov
parent 59be91e5e7
commit d39d1445d3
1 changed files with 11 additions and 2 deletions
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13
kernel/bpf/bpf_local_storage.c
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@ -88,8 +88,14 @@ void bpf_local_storage_free_rcu(struct rcu_head *rcu)
{
struct bpf_local_storage *local_storage;
/* If RCU Tasks Trace grace period implies RCU grace period, do
* kfree(), else do kfree_rcu().
*/
local_storage = container_of(rcu, struct bpf_local_storage, rcu);
kfree_rcu(local_storage, rcu);
if (rcu_trace_implies_rcu_gp())
kfree(local_storage);
else
kfree_rcu(local_storage, rcu);
}
static void bpf_selem_free_rcu(struct rcu_head *rcu)
@ -97,7 +103,10 @@ static void bpf_selem_free_rcu(struct rcu_head *rcu)
struct bpf_local_storage_elem *selem;
selem = container_of(rcu, struct bpf_local_storage_elem, rcu);
kfree_rcu(selem, rcu);
if (rcu_trace_implies_rcu_gp())
kfree(selem);
else
kfree_rcu(selem, rcu);
}
/* local_storage->lock must be held and selem->local_storage == local_storage.