diff mbox series

[bpf-next,v2,4/4] bpf: Use rcu_trace_implies_rcu_gp() for program array freeing

Message ID 20221014113946.965131-5-houtao@huaweicloud.com (mailing list archive)
State Accepted
Commit 4835f9ee980c1867584018e69cbf1f62d7844cb3
Delegated to: BPF
Headers show
Series Remove unnecessary RCU grace period chaining | expand

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Context Check Description
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netdev/fixes_present success Fixes tag not required for -next series
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netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 9 this patch: 9
netdev/cc_maintainers warning 2 maintainers not CCed: song@kernel.org martin.lau@linux.dev
netdev/build_clang success Errors and warnings before: 5 this patch: 5
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netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 9 this patch: 9
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 15 lines checked
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Commit Message

Hou Tao Oct. 14, 2022, 11:39 a.m. UTC 
From: Hou Tao <houtao1@huawei.com>

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>
---
 kernel/bpf/core.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 711fd293b6de..4bc5f46d7030 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -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)