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can: proc: skip stats calculation after reset in can_stat_update()

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Commit 80b5f90158 ("can: statistics: use atomic access in hot path")
introduced local snapshots of the statistics counters at the beginning
of can_stat_update(). When can_init_stats() resets the statistics, these
stale pre-reset snapshots are still used for the following total/current
/max calculations and overwrite the freshly reset values. Additionally a
jiffies tick between the snapshot and the reset could trigger a second
can_init_stats() call.

Merge the reset conditions into a single check and skip the calculation
for the current interval when the statistics have been reset.

Fixes: 80b5f90158 ("can: statistics: use atomic access in hot path")
Cc: stable@vger.kernel.org
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20261027-can-rx-lock-v12-6-eb5afc2d8b9b@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Oliver Hartkopp 2026-10-27 15:31:10 +01:00 committed by Marc Kleine-Budde
parent 12297f855b
commit 01b19ed9fa
1 changed files with 12 additions and 18 deletions
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30
net/can/proc.c
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@ -149,25 +149,18 @@ void can_stat_update(struct timer_list *t)
long tx_frames_delta = atomic_long_xchg(&pkg_stats->tx_frames_delta, 0);
long matches_delta = atomic_long_xchg(&pkg_stats->matches_delta, 0);
/* restart counting in timer context on user request */
if (user_reset)
can_init_stats(net);
/* restart counting on jiffies overflow */
if (j < pkg_stats->jiffies_init)
can_init_stats(net);
/* prevent overflow in calc_rate() */
if (rx_frames > (LONG_MAX / HZ))
can_init_stats(net);
/* prevent overflow in calc_rate() */
if (tx_frames > (LONG_MAX / HZ))
can_init_stats(net);
/* matches overflow - very improbable */
if (matches > (LONG_MAX / 100))
/*
* Restart counting in timer context on user request, on jiffies
* overflow or to prevent overflows in calc_rate() and in the
* match ratio calculation. The local snapshots are stale after
* the reset, so skip the calculation for this interval.
*/
if (user_reset || j < pkg_stats->jiffies_init ||
rx_frames > (LONG_MAX / HZ) || tx_frames > (LONG_MAX / HZ) ||
matches > (LONG_MAX / 100)) {
can_init_stats(net);
goto out;
}
/* calc total values */
if (rx_frames)
@ -196,6 +189,7 @@ void can_stat_update(struct timer_list *t)
if (pkg_stats->max_rx_match_ratio < pkg_stats->current_rx_match_ratio)
pkg_stats->max_rx_match_ratio = pkg_stats->current_rx_match_ratio;
out:
/* restart timer (one second) */
mod_timer(&net->can.stattimer, round_jiffies(jiffies + HZ));
}