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authorNiklas Söderlund <niklas.soderlund@corigine.com>2022-03-15 11:29:48 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2022-03-15 16:53:37 +0100
commit8fa42d78f6354bb96ad3a079dcbef528ca9fa9e0 (patch)
treee412f2ab38b815459697c72bf83781878f675dcd /samples
parent2486ab434b2c2a14e9237296db00b1e1b7ae3273 (diff)
downloadlinux-8fa42d78f6354bb96ad3a079dcbef528ca9fa9e0.tar.bz2
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')
-rw-r--r--samples/bpf/xdpsock_user.c6
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;