From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 C7FCC3B71B6; Wed, 30 Sep 2026 18:13:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791988; cv=none; b=ImQQ4eHWR7Tcfch2j1kjUji+4zQLjqVHRJ6Q299DiRaa3+AjUMsAasQH77E5VPWF4jcGg2Mnj984XqyH5XSG/goOcdcKOL4mpvF2NyWgMVgeSiQDMN37sb4i8TP7GlMw6F8F/FSLtYURWfXbQYq8QdmLhzEngbTWZ5LpuiTgtFs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791988; c=relaxed/simple; bh=puuCs3Ua0xxD4d8k4UJi9UYrPhEoFDfga2y6j0eChEQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=k7hTP9pUHslULQqqZq1s1lia7IUu+KIYHdHxczMu9xcH1ao7ypZNTOsSMiLcWoxqjHpwmbYjvlxtsB2pMLNK8IaiE8r8kmrsmBcLbxbvVCz3SqGKtkjINH1m+uF4impK/QHn1kFzPP5HYuekJ6hmTcVvYnKFIRONROdc9SyVcdY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Hz2EuM6C; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Hz2EuM6C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2FAB91F000FF; Wed, 30 Sep 2026 18:13:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790791987; bh=cs/j7Y6Jl4zq8FvWXoEzm2Mek6RWhz7K3Pc6PC6ihRU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Hz2EuM6CaGc0EAOuK05SJMr1epBzdYEUv+pkPq2oh4E0YN4xEz5oVVh6M0NseRJZz WZQSwTxHu1ZjL4VpKILYx5EUHC69Wol3ql29NXS6YCyKJmTSNBsjuT3riUq+nQKOqF leVegVLCIJWWtNUOXOFBOwFakUwXcOfvmZiG/E/g= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Karl Mehltretter , Arend van Spriel , Johannes Berg , Sasha Levin Subject: [PATCH 5.15 495/752] wifi: brcmfmac: fix lost 802.1x TX completion wakeup Date: Wed, 30 Sep 2026 17:26:05 +0200 Message-ID: <20260930152408.976007893@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Karl Mehltretter [ Upstream commit 621d90169cef6c8da5b6134db5c0c4e23cdd09ce ] brcmf_txfinalize() decrements pend_8021x_cnt before a lockless waitqueue_active() check. atomic_dec() does not order the decrement against the check. The waiter can therefore observe a nonzero count while the waker observes an empty queue, losing the final wakeup and delaying key installation until the 950 ms timeout. Add smp_mb__after_atomic() to order the decrement before the queue check. wait_event_timeout() provides the matching barrier. LKMM confirms that this forbids the lost-wakeup outcome. Fixes: 21fff75d2fb6 ("brcmfmac: use wait_event_timeout for 8021x pending count") Assisted-by: Claude:claude-fable-5 Signed-off-by: Karl Mehltretter Acked-by: Arend van Spriel Link: https://patch.msgid.link/20260811082702.44521-1-kmehltretter@gmail.com Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c index 109c13189206e..860376037265b 100644 --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c @@ -560,6 +560,8 @@ void brcmf_txfinalize(struct brcmf_if *ifp, struct sk_buff *txp, bool success) if (type == ETH_P_PAE) { atomic_dec(&ifp->pend_8021x_cnt); + /* Order the decrement before waitqueue_active() */ + smp_mb__after_atomic(); if (waitqueue_active(&ifp->pend_8021x_wait)) wake_up(&ifp->pend_8021x_wait); } -- 2.53.0