From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.simonwunderlich.de (mail.simonwunderlich.de [23.88.38.48]) (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 1AD8E3DA7E9 for ; Wed, 20 May 2026 11:54:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=23.88.38.48 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779278093; cv=none; b=YzNjnyQzrfHeQrG0fd5M5f3Sr2ZLbDoMdm9VJ7Jmisc3zbEJVAeLuuZp7MTy5NZXgDj036oqh0xDRGIX6tw4QrDnzbYMGKa8LKb/2/0OjoBfwlhKnjXwzAYZBhocdD+MHRYWNQILbs1T3LcPOrPojRH7vI4YtWLP45RaO67/8Ug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779278093; c=relaxed/simple; bh=dk6baIsQlOnNUobY8yD/AFM8D3qbSQvl9j6knypNyeA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HDLvTK4sE7WoFwjGmkLMwycvrK9BPziInSEXROsWjo1eW2pYjw7RP2x/ZcCpvyLljQQIKbqZ7Q6eSYYTzzxuRRzxv7nwXl7gfB3AUww3ejDouZZq/aUhjjRR6eYVIQf8wgmNcXEDfcOtPDWV1naqiMn1YpDls3ToYs9asrUxLbg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=simonwunderlich.de; spf=pass smtp.mailfrom=simonwunderlich.de; dkim=pass (2048-bit key) header.d=simonwunderlich.de header.i=@simonwunderlich.de header.b=b7Ls/IYP; arc=none smtp.client-ip=23.88.38.48 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=simonwunderlich.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=simonwunderlich.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=simonwunderlich.de header.i=@simonwunderlich.de header.b="b7Ls/IYP" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=simonwunderlich.de; s=09092022; t=1779278080; 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=BULy2aZ9XzqlKy9J1Q/CAm5WFiqNjLZhZVZXdidvFQ0=; b=b7Ls/IYPX/RJe83dNnKWBYXUgn9BvaLU73i59N8u7BPZ2UEGBBLTrtKMi9U7xe4dP7euHM iVOAEJH7jLB3m72YADla4h8B2CdnUNnBQ1NAE828Cg5rgT18NTA5u8zvXW43OQWWdpYQsC loMfnqexwMWoKdK+pBs2m0mAzedVI4eJ7r1bTlTNmq2F/E9yVRFsN4Axg1xyedWOH5uykU 9udTnIFYbzhEXIKvY4DlLJ+/kiwiS/8fBKDHKKA8mmVVlRzXl7cmnutKTiaDelwlCg1TaO P/+Mrg9vMx8FhrfkXAN95iofShWFeLxPwIJcevjuSdpiF1u6mTFsamAN04UTcw== From: Simon Wunderlich To: netdev@vger.kernel.org Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , b.a.t.m.a.n@lists.open-mesh.org, Sven Eckelmann , stable@kernel.org, Simon Wunderlich Subject: [PATCH net 05/11] batman-adv: tp_meter: fix race condition in send error reporting Date: Wed, 20 May 2026 13:54:16 +0200 Message-ID: <20260520115422.53552-6-sw@simonwunderlich.de> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260520115422.53552-1-sw@simonwunderlich.de> References: <20260520115422.53552-1-sw@simonwunderlich.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: Sven Eckelmann batadv_tp_sender_shutdown() previously used two separate variables to track session state: sending (an atomic flag indicating whether the session was active) and reason (a plain enum storing the stop reason). This introduced a race window between the two writes: after sending was cleared to 0, batadv_tp_send() could observe the stopped state and call batadv_tp_sender_end() before reason was written, causing the wrong stop reason to be reported to the caller. Fix this by consolidating both variables into a single atomic send_result, which holds 0 while the session is running and the stop reason once it ends. Cc: stable@kernel.org Fixes: 33a3bb4a3345 ("batman-adv: throughput meter implementation") Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich --- net/batman-adv/tp_meter.c | 40 ++++++++++++++++++++++++--------------- net/batman-adv/types.h | 10 +++++----- 2 files changed, 30 insertions(+), 20 deletions(-) diff --git a/net/batman-adv/tp_meter.c b/net/batman-adv/tp_meter.c index 1fd1526059d8a..3ce6d9b2c9f3b 100644 --- a/net/batman-adv/tp_meter.c +++ b/net/batman-adv/tp_meter.c @@ -413,11 +413,14 @@ static void batadv_tp_sender_cleanup(struct batadv_tp_vars *tp_vars) static void batadv_tp_sender_end(struct batadv_priv *bat_priv, struct batadv_tp_vars *tp_vars) { + enum batadv_tp_meter_reason reason; u32 session_cookie; + reason = atomic_read(&tp_vars->send_result); + batadv_dbg(BATADV_DBG_TP_METER, bat_priv, "Test towards %pM finished..shutting down (reason=%d)\n", - tp_vars->other_end, tp_vars->reason); + tp_vars->other_end, reason); batadv_dbg(BATADV_DBG_TP_METER, bat_priv, "Last timing stats: SRTT=%ums RTTVAR=%ums RTO=%ums\n", @@ -430,7 +433,7 @@ static void batadv_tp_sender_end(struct batadv_priv *bat_priv, session_cookie = batadv_tp_session_cookie(tp_vars->session, tp_vars->icmp_uid); - batadv_tp_batctl_notify(tp_vars->reason, + batadv_tp_batctl_notify(reason, tp_vars->other_end, bat_priv, tp_vars->start_time, @@ -446,10 +449,18 @@ static void batadv_tp_sender_end(struct batadv_priv *bat_priv, static void batadv_tp_sender_shutdown(struct batadv_tp_vars *tp_vars, enum batadv_tp_meter_reason reason) { - if (atomic_xchg(&tp_vars->sending, 0) != 1) - return; + atomic_cmpxchg(&tp_vars->send_result, 0, reason); +} - tp_vars->reason = reason; +/** + * batadv_tp_sender_stopped() - check if tp session was stopped with reason + * @tp_vars: the private data of the current TP meter session + * + * Return: whether stop reason was found + */ +static bool batadv_tp_sender_stopped(struct batadv_tp_vars *tp_vars) +{ + return atomic_read(&tp_vars->send_result) != 0; } /** @@ -479,7 +490,7 @@ static void batadv_tp_reset_sender_timer(struct batadv_tp_vars *tp_vars) /* most of the time this function is invoked while normal packet * reception... */ - if (unlikely(atomic_read(&tp_vars->sending) == 0)) + if (unlikely(batadv_tp_sender_stopped(tp_vars))) /* timer ref will be dropped in batadv_tp_sender_cleanup */ return; @@ -499,7 +510,7 @@ static void batadv_tp_sender_timeout(struct timer_list *t) struct batadv_tp_vars *tp_vars = timer_container_of(tp_vars, t, timer); struct batadv_priv *bat_priv = tp_vars->bat_priv; - if (atomic_read(&tp_vars->sending) == 0) + if (batadv_tp_sender_stopped(tp_vars)) return; /* if the user waited long enough...shutdown the test */ @@ -661,7 +672,7 @@ static void batadv_tp_recv_ack(struct batadv_priv *bat_priv, if (unlikely(tp_vars->role != BATADV_TP_SENDER)) goto out; - if (unlikely(atomic_read(&tp_vars->sending) == 0)) + if (unlikely(batadv_tp_sender_stopped(tp_vars))) goto out; /* old ACK? silently drop it.. */ @@ -827,21 +838,21 @@ static int batadv_tp_send(void *arg) if (unlikely(tp_vars->role != BATADV_TP_SENDER)) { err = BATADV_TP_REASON_DST_UNREACHABLE; - tp_vars->reason = err; + batadv_tp_sender_shutdown(tp_vars, err); goto out; } orig_node = batadv_orig_hash_find(bat_priv, tp_vars->other_end); if (unlikely(!orig_node)) { err = BATADV_TP_REASON_DST_UNREACHABLE; - tp_vars->reason = err; + batadv_tp_sender_shutdown(tp_vars, err); goto out; } primary_if = batadv_primary_if_get_selected(bat_priv); if (unlikely(!primary_if)) { err = BATADV_TP_REASON_DST_UNREACHABLE; - tp_vars->reason = err; + batadv_tp_sender_shutdown(tp_vars, err); goto out; } @@ -860,7 +871,7 @@ static int batadv_tp_send(void *arg) queue_delayed_work(batadv_event_workqueue, &tp_vars->finish_work, msecs_to_jiffies(tp_vars->test_length)); - while (atomic_read(&tp_vars->sending) != 0) { + while (!batadv_tp_sender_stopped(tp_vars)) { if (unlikely(!batadv_tp_avail(tp_vars, payload_len))) { batadv_tp_wait_available(tp_vars, payload_len); continue; @@ -883,8 +894,7 @@ static int batadv_tp_send(void *arg) "Meter: %s() cannot send packets (%d)\n", __func__, err); /* ensure nobody else tries to stop the thread now */ - if (atomic_xchg(&tp_vars->sending, 0) == 1) - tp_vars->reason = err; + batadv_tp_sender_shutdown(tp_vars, err); break; } @@ -1006,7 +1016,7 @@ void batadv_tp_start(struct batadv_priv *bat_priv, const u8 *dst, ether_addr_copy(tp_vars->other_end, dst); kref_init(&tp_vars->refcount); tp_vars->role = BATADV_TP_SENDER; - atomic_set(&tp_vars->sending, 1); + atomic_set(&tp_vars->send_result, 0); memcpy(tp_vars->session, session_id, sizeof(session_id)); tp_vars->icmp_uid = icmp_uid; diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index c8c3e8064f00c..fb0e4cb89d79a 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -1320,15 +1320,15 @@ struct batadv_tp_vars { /** @role: receiver/sender modi */ enum batadv_tp_meter_role role; - /** @sending: sending binary semaphore: 1 if sending, 0 is not */ - atomic_t sending; + /** + * @send_result: 0 when sending is ongoing and otherwise + * enum batadv_tp_meter_reason + */ + atomic_t send_result; /** @receiving: receiving binary semaphore: 1 if receiving, 0 is not */ atomic_t receiving; - /** @reason: reason for a stopped session */ - enum batadv_tp_meter_reason reason; - /** @finish_work: work item for the finishing procedure */ struct delayed_work finish_work; -- 2.47.3