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author | Niklas Söderlund <niklas.soderlund@corigine.com> | 2022-03-15 13:29:48 +0300 |
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committer | Daniel Borkmann <daniel@iogearbox.net> | 2022-03-15 18:53:37 +0300 |
commit | 8fa42d78f6354bb96ad3a079dcbef528ca9fa9e0 (patch) | |
tree | e412f2ab38b815459697c72bf83781878f675dcd /samples/bpf/xdpsock_user.c | |
parent | 2486ab434b2c2a14e9237296db00b1e1b7ae3273 (diff) | |
download | linux-8fa42d78f6354bb96ad3a079dcbef528ca9fa9e0.tar.xz |
samples/bpf, xdpsock: Fix race when running for fix duration of time
When running xdpsock for a fix duration of time before terminating
using --duration=<n>, there is a race condition that may cause xdpsock
to terminate immediately.
When running for a fixed duration of time the check to determine when to
terminate execution is in is_benchmark_done() and is being executed in
the context of the poller thread,
if (opt_duration > 0) {
unsigned long dt = (get_nsecs() - start_time);
if (dt >= opt_duration)
benchmark_done = true;
}
However start_time is only set after the poller thread have been
created. This leaves a small window when the poller thread is starting
and calls is_benchmark_done() for the first time that start_time is not
yet set. In that case start_time have its initial value of 0 and the
duration check fails as it do not correlate correctly for the
applications start time and immediately sets benchmark_done which in
turn terminates the xdpsock application.
Fix this by setting start_time before creating the poller thread.
Fixes: d3f11b018f6c ("samples/bpf: xdpsock: Add duration option to specify how long to run")
Signed-off-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220315102948.466436-1-niklas.soderlund@corigine.com
Diffstat (limited to 'samples/bpf/xdpsock_user.c')
-rw-r--r-- | samples/bpf/xdpsock_user.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c index 19288a2bbc75..6f3fe30ad283 100644 --- a/samples/bpf/xdpsock_user.c +++ b/samples/bpf/xdpsock_user.c @@ -1984,15 +1984,15 @@ int main(int argc, char **argv) setlocale(LC_ALL, ""); + prev_time = get_nsecs(); + start_time = prev_time; + if (!opt_quiet) { ret = pthread_create(&pt, NULL, poller, NULL); if (ret) exit_with_error(ret); } - prev_time = get_nsecs(); - start_time = prev_time; - /* Configure sched priority for better wake-up accuracy */ memset(&schparam, 0, sizeof(schparam)); schparam.sched_priority = opt_schprio; |