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authorOliver Hartkopp <socketcan@hartkopp.net>2025-03-10 15:33:53 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2025-04-10 14:29:42 +0200
commit12d344d74ce322bb2a951fe24e6cb085b6b073ca (patch)
tree22ff9b8e5bd13ad9a9c93f9121421f5442e06566 /net
parentd6ae75c3ba1fb0dc388b0fed11b962b8aeed21e2 (diff)
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can: statistics: use atomic access in hot path
[ Upstream commit 80b5f90158d1364cbd80ad82852a757fc0692bf2 ] In can_send() and can_receive() CAN messages and CAN filter matches are counted to be visible in the CAN procfs files. KCSAN detected a data race within can_send() when two CAN frames have been generated by a timer event writing to the same CAN netdevice at the same time. Use atomic operations to access the statistics in the hot path to fix the KCSAN complaint. Reported-by: syzbot+78ce4489b812515d5e4d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/67cd717d.050a0220.e1a89.0006.GAE@google.com Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Link: https://patch.msgid.link/20250310143353.3242-1-socketcan@hartkopp.net Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net')
-rw-r--r--net/can/af_can.c12
-rw-r--r--net/can/af_can.h12
-rw-r--r--net/can/proc.c46
3 files changed, 39 insertions, 31 deletions
diff --git a/net/can/af_can.c b/net/can/af_can.c
index bc06016a4fe9..d2fd12da30c6 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -288,8 +288,8 @@ int can_send(struct sk_buff *skb, int loop)
netif_rx_ni(newskb);
/* update statistics */
- pkg_stats->tx_frames++;
- pkg_stats->tx_frames_delta++;
+ atomic_long_inc(&pkg_stats->tx_frames);
+ atomic_long_inc(&pkg_stats->tx_frames_delta);
return 0;
@@ -647,8 +647,8 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
int matches;
/* update statistics */
- pkg_stats->rx_frames++;
- pkg_stats->rx_frames_delta++;
+ atomic_long_inc(&pkg_stats->rx_frames);
+ atomic_long_inc(&pkg_stats->rx_frames_delta);
/* create non-zero unique skb identifier together with *skb */
while (!(can_skb_prv(skb)->skbcnt))
@@ -669,8 +669,8 @@ static void can_receive(struct sk_buff *skb, struct net_device *dev)
consume_skb(skb);
if (matches > 0) {
- pkg_stats->matches++;
- pkg_stats->matches_delta++;
+ atomic_long_inc(&pkg_stats->matches);
+ atomic_long_inc(&pkg_stats->matches_delta);
}
}
diff --git a/net/can/af_can.h b/net/can/af_can.h
index 7c2d9161e224..22f3352c77fe 100644
--- a/net/can/af_can.h
+++ b/net/can/af_can.h
@@ -66,9 +66,9 @@ struct receiver {
struct can_pkg_stats {
unsigned long jiffies_init;
- unsigned long rx_frames;
- unsigned long tx_frames;
- unsigned long matches;
+ atomic_long_t rx_frames;
+ atomic_long_t tx_frames;
+ atomic_long_t matches;
unsigned long total_rx_rate;
unsigned long total_tx_rate;
@@ -82,9 +82,9 @@ struct can_pkg_stats {
unsigned long max_tx_rate;
unsigned long max_rx_match_ratio;
- unsigned long rx_frames_delta;
- unsigned long tx_frames_delta;
- unsigned long matches_delta;
+ atomic_long_t rx_frames_delta;
+ atomic_long_t tx_frames_delta;
+ atomic_long_t matches_delta;
};
/* persistent statistics */
diff --git a/net/can/proc.c b/net/can/proc.c
index a5fc63c78370..ea442ddd4fd9 100644
--- a/net/can/proc.c
+++ b/net/can/proc.c
@@ -123,6 +123,13 @@ void can_stat_update(struct timer_list *t)
struct can_pkg_stats *pkg_stats = net->can.pkg_stats;
unsigned long j = jiffies; /* snapshot */
+ long rx_frames = atomic_long_read(&pkg_stats->rx_frames);
+ long tx_frames = atomic_long_read(&pkg_stats->tx_frames);
+ long matches = atomic_long_read(&pkg_stats->matches);
+ long rx_frames_delta = atomic_long_read(&pkg_stats->rx_frames_delta);
+ long tx_frames_delta = atomic_long_read(&pkg_stats->tx_frames_delta);
+ long matches_delta = atomic_long_read(&pkg_stats->matches_delta);
+
/* restart counting in timer context on user request */
if (user_reset)
can_init_stats(net);
@@ -132,35 +139,33 @@ void can_stat_update(struct timer_list *t)
can_init_stats(net);
/* prevent overflow in calc_rate() */
- if (pkg_stats->rx_frames > (ULONG_MAX / HZ))
+ if (rx_frames > (LONG_MAX / HZ))
can_init_stats(net);
/* prevent overflow in calc_rate() */
- if (pkg_stats->tx_frames > (ULONG_MAX / HZ))
+ if (tx_frames > (LONG_MAX / HZ))
can_init_stats(net);
/* matches overflow - very improbable */
- if (pkg_stats->matches > (ULONG_MAX / 100))
+ if (matches > (LONG_MAX / 100))
can_init_stats(net);
/* calc total values */
- if (pkg_stats->rx_frames)
- pkg_stats->total_rx_match_ratio = (pkg_stats->matches * 100) /
- pkg_stats->rx_frames;
+ if (rx_frames)
+ pkg_stats->total_rx_match_ratio = (matches * 100) / rx_frames;
pkg_stats->total_tx_rate = calc_rate(pkg_stats->jiffies_init, j,
- pkg_stats->tx_frames);
+ tx_frames);
pkg_stats->total_rx_rate = calc_rate(pkg_stats->jiffies_init, j,
- pkg_stats->rx_frames);
+ rx_frames);
/* calc current values */
- if (pkg_stats->rx_frames_delta)
+ if (rx_frames_delta)
pkg_stats->current_rx_match_ratio =
- (pkg_stats->matches_delta * 100) /
- pkg_stats->rx_frames_delta;
+ (matches_delta * 100) / rx_frames_delta;
- pkg_stats->current_tx_rate = calc_rate(0, HZ, pkg_stats->tx_frames_delta);
- pkg_stats->current_rx_rate = calc_rate(0, HZ, pkg_stats->rx_frames_delta);
+ pkg_stats->current_tx_rate = calc_rate(0, HZ, tx_frames_delta);
+ pkg_stats->current_rx_rate = calc_rate(0, HZ, rx_frames_delta);
/* check / update maximum values */
if (pkg_stats->max_tx_rate < pkg_stats->current_tx_rate)
@@ -173,9 +178,9 @@ void can_stat_update(struct timer_list *t)
pkg_stats->max_rx_match_ratio = pkg_stats->current_rx_match_ratio;
/* clear values for 'current rate' calculation */
- pkg_stats->tx_frames_delta = 0;
- pkg_stats->rx_frames_delta = 0;
- pkg_stats->matches_delta = 0;
+ atomic_long_set(&pkg_stats->tx_frames_delta, 0);
+ atomic_long_set(&pkg_stats->rx_frames_delta, 0);
+ atomic_long_set(&pkg_stats->matches_delta, 0);
/* restart timer (one second) */
mod_timer(&net->can.stattimer, round_jiffies(jiffies + HZ));
@@ -217,9 +222,12 @@ static int can_stats_proc_show(struct seq_file *m, void *v)
struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
seq_putc(m, '\n');
- seq_printf(m, " %8ld transmitted frames (TXF)\n", pkg_stats->tx_frames);
- seq_printf(m, " %8ld received frames (RXF)\n", pkg_stats->rx_frames);
- seq_printf(m, " %8ld matched frames (RXMF)\n", pkg_stats->matches);
+ seq_printf(m, " %8ld transmitted frames (TXF)\n",
+ atomic_long_read(&pkg_stats->tx_frames));
+ seq_printf(m, " %8ld received frames (RXF)\n",
+ atomic_long_read(&pkg_stats->rx_frames));
+ seq_printf(m, " %8ld matched frames (RXMF)\n",
+ atomic_long_read(&pkg_stats->matches));
seq_putc(m, '\n');
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-08 21:17:56 +0000