From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.white.stw.pengutronix.de (mx1.white.stw.pengutronix.de [185.203.200.13]) (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 745573E7166; Sun, 18 Oct 2026 16:44:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=185.203.200.13 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792341869; cv=pass; b=ZFMPOL50RX7lqIuTdJ9DBDwXi2VhM4XpdnRDymiAPzHrti4Eg4VNzy/DxSyBFyL2UHNZm+K8sO/9CS4hjA/b4WB+V1DNoEckZyvObc5b2jSHj7ZzbpqeCaLc2fr9fXhptWqsHRNiWY18beSig3NHrBFLB7XgLEYfM3/cm7+kKGg= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792341869; c=relaxed/simple; bh=dgKHErKsIyVita3zOnCK1mXc/fPgzHpDFHjWQcwpdi0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=K0e1cXn67Sc1j+oshk98yp2dDNDQ5dOA5IYhc7YKMCRDrnW4MnK0l353P2jO2A8gbLA9QjRU2SKb0nkjNHd9NRtsyfZPpnjQgA+us3JMYkPdDlMLwhB2DAcvUKqUfFRIknDxbJ3h131LHOnjzeHag4Ko46MrseKZuHvhrvCRXM4= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de; spf=pass smtp.mailfrom=pengutronix.de; dkim=pass (2048-bit key) header.d=pengutronix.de header.i=@pengutronix.de header.b=EFzjcP9D; arc=pass smtp.client-ip=185.203.200.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=pengutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=pengutronix.de header.i=@pengutronix.de header.b="EFzjcP9D" Received: from drehscheibe.grey.stw.pengutronix.de (drehscheibe.grey.stw.pengutronix.de [IPv6:2a0a:edc0:0:c01:1d::a2]) (Authenticated sender: relay-from-drehscheibe.grey.stw.pengutronix.de) by mx1.white.stw.pengutronix.de (Postfix) with ESMTPSA id 06193202834; Sun, 18 Oct 2026 18:44:20 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pengutronix.de; s=20260414; t=1792341860; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pydj8cHNUhBQw6xhIpT6PBHMjbVNX0FUvQdCoFVhtm8=; b=EFzjcP9DaHJ9WqZkRcouWvZ7He7QR3A7B00u0nfiplHCSWLDJ4a1l6BPmpvKNrd+UijEAg EUjTOAN3c8Q5+tI+qmA9nKqlhJFAdeoJtgsMNcwJJznoNmMowYP51iB7JfwE+0/zPFccGX NLckil1RmKFPrg8KqfjceaBpVO513Anzpcd7eZM7zmSdjLFR/cOb6j6/ymFv7v25AHf+9r pUVYaWl01AQ/BjNxEDbJBLsXr/759esvcSpk/oq9iYQmP5YVUE62Qa1Dw8McTFPe4k9RbY lc8lQODv+Rl4lnvcJJTscq5Q78VKURWUzeq2a7R73pCAjXBnK7Lho0e7fXUTgQ== ARC-Seal: i=1; s=20260414; d=pengutronix.de; t=1792341860; a=rsa-sha256; cv=none; b=VIqEy4Kht8c2czKX1wPTY/K0LkAJ1ouZTdMRS8tOI3MnWEfa195el+nFh5JLJstxnTJVDg FVU70s9IE/wHkKmCLyxJ8EOSXCeYZuosfodmTluhNimGwqYDNsX6lbGaD45UruSfPOpeMI Sk+96GjpHHBHb0GsqYaqrIMFBn6kpaGF5TyN28I1urjchgo6sjqdvji6fiRlg6x7rSDEkB 0Pep8lG9il9D7PM/NYSmm++o40PRl93h7AeN3ZDfxBU5Hr2mPZCwBRwqWxubaM7FmJ68R4 NySdCHACNsdTinMKEFYqzp3/6qIn9TepnGnjzMNmv0HNLRyTCkdBzz8yvtZipA== ARC-Authentication-Results: i=1; ORIGINATING; auth=pass smtp.auth=relay-from-drehscheibe.grey.stw.pengutronix.de smtp.mailfrom=mkl@pengutronix.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=pengutronix.de; s=20260414; t=1792341860; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pydj8cHNUhBQw6xhIpT6PBHMjbVNX0FUvQdCoFVhtm8=; b=dtEpQqczvfY29rukeLYFb/jAGqGw2A46k2TadswqsB9GJBuk1TcKqGLPkW9wyrQ3SFd1Lb lGpFRP7hF8Oa+Xsa4GpyYN+CmafzU5LICh2JoqcN8lYXQogr74DmHcwSGpmRS8P7YDOhIx A9RxUgi1M4+cvfY0V8foWY8Xre7PITjQx9VvapWQwB/mZQlxXSMfyknSDrNnfkZjiYSU8z +GqGvN9/D/3XTX7lDfdHinwBdISyDqiMPsu4K1TVq4ogeL4XFGk10e9WRWQKpjwy+aW6YE +/B7M1/Hbtwl4egUe5vN37UzatKJUxMDtEbdEugJebhZJK+xXuwIAdJADK/DBg== Received: from moin.white.stw.pengutronix.de ([2a0a:edc0:0:b01:1d::7b] helo=bjornoya.blackshift.org) by drehscheibe.grey.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1xITzf-0006SN-2y; Sun, 18 Oct 2026 18:44:19 +0200 Received: from blackshift.org (p4ffb23c7.dip0.t-ipconnect.de [79.251.35.199]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519MLKEM768 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) (Authenticated sender: mkl-all@blackshift.org) by smtp.blackshift.org (Postfix) with ESMTPSA id A04745C7D95; Sun, 18 Oct 2026 16:44:19 +0000 (UTC) From: Marc Kleine-Budde To: netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org, kernel@pengutronix.de, Runyu Xiao , stable@vger.kernel.org, Oliver Hartkopp , Marc Kleine-Budde Subject: [PATCH net-next 05/12] can: proc: reset pkg_stats atomics individually Date: Sun, 18 Oct 2026 18:41:41 +0200 Message-ID: <20261018164417.1540449-6-mkl@pengutronix.de> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261018164417.1540449-1-mkl@pengutronix.de> References: <20261018164417.1540449-1-mkl@pengutronix.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Runyu Xiao Commit 80b5f90158d1 ("can: statistics: use atomic access in hot path") converted several members of struct can_pkg_stats to atomic_long_t and updated the hot TX/RX and procfs read paths to use atomic_long_*() helpers. However, can_init_stats() still clears the whole struct with memset(). can_init_stats() is reached from can_stat_update() in timer context and also from the procfs reset path. Those paths can run while the TX/RX hot paths are concurrently updating rx_frames, tx_frames, matches and their *_delta counters. Hitting the whole-struct memset() in that window performs plain writes to fields that otherwise follow an atomic_long_t access contract, which can lose or mix live statistics updates. This issue was found by source-level API-misuse analysis looking for whole-object resets left behind after atomic_long_t conversions, then manually audited on Linux v6.18.21. Replace the whole-struct memset() with a helper that resets the atomic_long_t counters via atomic_long_set() and clears the derived scalar statistics explicitly. This preserves the existing reset semantics for scalar fields while restoring atomic access discipline for the live counters. Build-tested by compiling net/can/proc.o on x86_64 netdev/main. Runtime-tested with a QEMU + vcan setup on Linux v6.18.21 by driving concurrent traffic and reset_stats reads, which reproduced inconsistent exported statistics before the fix. [Hartkopp] can_stat_update() also read the *_delta counters at the beginning and cleared them with atomic_long_set() at the end. Increments from the hot path in between were lost for both the current and the next interval. Use atomic_long_xchg() to fetch and clear the *_delta counters in one atomic step instead. Fixes: 80b5f90158d1 ("can: statistics: use atomic access in hot path") Cc: stable@vger.kernel.org Signed-off-by: Runyu Xiao Acked-by: Oliver Hartkopp Signed-off-by: Oliver Hartkopp Link: https://patch.msgid.link/20261016110905.422684-1-socketcan@hartkopp.net Signed-off-by: Marc Kleine-Budde --- net/can/proc.c | 39 +++++++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 10 deletions(-) diff --git a/net/can/proc.c b/net/can/proc.c index de4d05ae3459..70104f13077e 100644 --- a/net/can/proc.c +++ b/net/can/proc.c @@ -76,16 +76,39 @@ static const char rx_list_name[][8] = { * af_can statistics stuff */ +static void can_reset_pkg_stats(struct can_pkg_stats *pkg_stats) +{ + atomic_long_set(&pkg_stats->rx_frames, 0); + atomic_long_set(&pkg_stats->tx_frames, 0); + atomic_long_set(&pkg_stats->matches, 0); + + pkg_stats->total_rx_rate = 0; + pkg_stats->total_tx_rate = 0; + pkg_stats->total_rx_match_ratio = 0; + + pkg_stats->current_rx_rate = 0; + pkg_stats->current_tx_rate = 0; + pkg_stats->current_rx_match_ratio = 0; + + pkg_stats->max_rx_rate = 0; + pkg_stats->max_tx_rate = 0; + pkg_stats->max_rx_match_ratio = 0; + + atomic_long_set(&pkg_stats->rx_frames_delta, 0); + atomic_long_set(&pkg_stats->tx_frames_delta, 0); + atomic_long_set(&pkg_stats->matches_delta, 0); +} + static void can_init_stats(struct net *net) { struct can_pkg_stats *pkg_stats = net->can.pkg_stats; struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats; /* - * This memset function is called from a timer context (when + * This stats reset is called from a timer context (when * can_stattimer is active which is the default) OR in a process * context (reading the proc_fs when can_stattimer is disabled). */ - memset(pkg_stats, 0, sizeof(struct can_pkg_stats)); + can_reset_pkg_stats(pkg_stats); pkg_stats->jiffies_init = jiffies; rcv_lists_stats->stats_reset++; @@ -121,9 +144,10 @@ void can_stat_update(struct timer_list *t) 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); + /* fetch and clear values for 'current rate' calculation */ + long rx_frames_delta = atomic_long_xchg(&pkg_stats->rx_frames_delta, 0); + 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) @@ -172,11 +196,6 @@ 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; - /* clear values for 'current rate' calculation */ - 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)); } -- 2.53.0