From: Niklas Söderlund <niklas.soderlund@xxxxxxxxxxxx>
[ Upstream commit 8fa42d78f6354bb96ad3a079dcbef528ca9fa9e0 ]
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@xxxxxxxxxxxx>
Signed-off-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20220315102948.466436-1-niklas.soderlund@xxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
samples/bpf/xdpsock_user.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
index aa50864e4415..9f3446af50ce 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;
--
2.34.1
