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authorDaniel Borkmann <daniel@iogearbox.net>2016-06-27 21:38:11 +0200
committerDavid S. Miller <davem@davemloft.net>2016-06-29 05:42:55 -0400
commitceb56070359b7329b5678b5d95a376fcb24767be (patch)
tree0f6deeff3c087009986f95158f27e1d2bd9ae549 /kernel
parent565ce8f32ac4a233b474f401e1d3e7e1de0a31fd (diff)
downloadlinux-ceb56070359b7329b5678b5d95a376fcb24767be.tar.gz
bpf, perf: delay release of BPF prog after grace period
Commit dead9f29ddcc ("perf: Fix race in BPF program unregister") moved destruction of BPF program from free_event_rcu() callback to __free_event(), which is problematic if used with tail calls: if prog A is attached as trace event directly, but at the same time present in a tail call map used by another trace event program elsewhere, then we need to delay destruction via RCU grace period since it can still be in use by the program doing the tail call (the prog first needs to be dropped from the tail call map, then trace event with prog A attached destroyed, so we get immediate destruction). Fixes: dead9f29ddcc ("perf: Fix race in BPF program unregister") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Cc: Jann Horn <jann@thejh.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/core.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 274450efea90..d00c47b67a97 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7531,7 +7531,7 @@ static void perf_event_free_bpf_prog(struct perf_event *event)
prog = event->tp_event->prog;
if (prog) {
event->tp_event->prog = NULL;
- bpf_prog_put(prog);
+ bpf_prog_put_rcu(prog);
}
}