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authorLorenz Bauer <lmb@cloudflare.com>2021-09-28 12:30:59 +0300
committerAlexei Starovoitov <ast@kernel.org>2021-09-30 00:10:05 +0300
commitde21d8bf777240c6d6dfefa39b4925729e32c0fd (patch)
treea62f83fdc7bfe7b37db6455234c9992a31136834 /net/bpf
parent66fe33241726d1f872e55d95a35c063d58602ae1 (diff)
downloadlinux-de21d8bf777240c6d6dfefa39b4925729e32c0fd.tar.xz
bpf: Do not invoke the XDP dispatcher for PROG_RUN with single repeat
We have a unit test that invokes an XDP program with 1m different inputs, aka 1m BPF_PROG_RUN syscalls. We run this test concurrently with slight variations in how we generated the input. Since commit f23c4b3924d2 ("bpf: Start using the BPF dispatcher in BPF_TEST_RUN") the unit test has slowed down significantly. Digging deeper reveals that the concurrent tests are serialised in the kernel on the XDP dispatcher. This is a global resource that is protected by a mutex, on which we contend. Fix this by not calling into the XDP dispatcher if we only want to perform a single run of the BPF program. See: https://lore.kernel.org/bpf/CACAyw9_y4QumOW35qpgTbLsJ532uGq-kVW-VESJzGyiZkypnvw@mail.gmail.com/ Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210928093100.27124-1-lmb@cloudflare.com
Diffstat (limited to 'net/bpf')
-rw-r--r--net/bpf/test_run.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index fcb2f493f710..6593a71dba5f 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -803,7 +803,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
if (ret)
goto free_data;
- bpf_prog_change_xdp(NULL, prog);
+ if (repeat > 1)
+ bpf_prog_change_xdp(NULL, prog);
ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true);
/* We convert the xdp_buff back to an xdp_md before checking the return
* code so the reference count of any held netdevice will be decremented
@@ -824,7 +825,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
sizeof(struct xdp_md));
out:
- bpf_prog_change_xdp(prog, NULL);
+ if (repeat > 1)
+ bpf_prog_change_xdp(prog, NULL);
free_data:
kfree(data);
free_ctx: