From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7DAED1CBA02; Tue, 25 Mar 2025 18:42:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742928163; cv=none; b=Q6Dp4TmJqjtE+/e6novRsqoXdNZEZJuBcmmc0KOoxc5RIZzOkMgCTn76RqKwoM6+ZjGJSs6g/7iGD9xqt07pzDnwLnyj+mTGZiHOtjTt6yLuUBFmymFIKsOr2pI3DvjGjbKgKwTq6hsBS8LJ/6fQC1x3AlsHxioPdzy7PbZX7Wc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742928163; c=relaxed/simple; bh=fW5tuiDIaABRDPN2atUvbHCcLI/ZT07db+kDwcop6O0=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=Q9OstZZKytsI4+xXwgzv1LgNpDs0YNXaIb+PDfpyZ/IIoY12/CKdD3SIbQV+EVYGv6bwdT6NA8Z0L5LM3R1Rb8n98uyqxQ851CdvUDbAZJ0/smchQQ31j+juw2ESadcZorlnPhhw4FsL0QSgrDqdWOmL5yHz6eLcz5yFDMmkPkI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dXS3nnUU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dXS3nnUU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00998C4CEE4; Tue, 25 Mar 2025 18:42:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742928161; bh=fW5tuiDIaABRDPN2atUvbHCcLI/ZT07db+kDwcop6O0=; h=From:To:Cc:Subject:Date:From; b=dXS3nnUU/n0tTd1xQo1zTqr30LxX6Grd0d7itmgGbs4LiWC6gVcggPvjkd4sKGVgO FuoYU3vKJihl/dED7IN7mFWuO6SVY7HFqvqTLZq4FWPW5JT/O/5tQViDSqnXCiVXRl YN2Q13y4y3JHA41tawBb0FrMQRg0g0OanVcG0V9ePtngYSU8Pxy/l5wnpltdDElWEu MDwqqHEoFkW61cdaRs4QY1BqpCifLhIBlDcqoMWHhniStRAgfUJyf+w9iLCPA8otHV xXgGP79hpgAoWCQqitW9tw3Ddz8G8/PM/3fEmtECknbyz8sE9jubnx/aOrR9fxZGp/ p8Y5734EgIVyQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Oliver Hartkopp , syzbot+78ce4489b812515d5e4d@syzkaller.appspotmail.com, Vincent Mailhol , Marc Kleine-Budde , Sasha Levin , linux-can@vger.kernel.org Subject: [PATCH AUTOSEL 6.12 1/5] can: statistics: use atomic access in hot path Date: Tue, 25 Mar 2025 14:42:31 -0400 Message-Id: <20250325184236.2152255-1-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.12.20 Content-Transfer-Encoding: 8bit From: Oliver Hartkopp [ 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 Reviewed-by: Vincent Mailhol Link: https://patch.msgid.link/20250310143353.3242-1-socketcan@hartkopp.net Signed-off-by: Marc Kleine-Budde Signed-off-by: Sasha Levin --- net/can/af_can.c | 12 ++++++------ net/can/af_can.h | 12 ++++++------ net/can/proc.c | 46 +++++++++++++++++++++++++++------------------- 3 files changed, 39 insertions(+), 31 deletions(-) diff --git a/net/can/af_can.c b/net/can/af_can.c index 01f3fbb3b67dc..65230e81fa08c 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -287,8 +287,8 @@ int can_send(struct sk_buff *skb, int loop) netif_rx(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 7c2d9161e2245..22f3352c77fec 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 bbce97825f13f..25fdf060e30d0 100644 --- a/net/can/proc.c +++ b/net/can/proc.c @@ -118,6 +118,13 @@ 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); @@ -127,35 +134,33 @@ 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) @@ -168,9 +173,9 @@ 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)); @@ -214,9 +219,12 @@ 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'); -- 2.39.5