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 F3E263A16BA; Sat, 12 Sep 2026 18:39:14 +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=1789238356; cv=none; b=ROGvlD3f/d7coHsLKoyZAAaFbAmj1y2I4vP99G+L4XsL3fD4x6od959CV4bQkMxRscurL4uTXoJLNZ6sjRa18hHM80Qp4PBViYLq8d9oChR3LdqaEnm96EwCsBfKxsw/dEkfUH9pQ+ENOtGmAjq/mC7koOgBvjsUUs+ulfTl84U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789238356; c=relaxed/simple; bh=O3L+lAHT4/gAByBhuqXr4ad1VDoZ8ty//AwLXq/wdv0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VZZgOAW5MCp40PBg+dGbK2BZH8DOMXwyEVSQ2KG0Icqms1RfMdjXaFSj55ouqN/EH/6+Ck5k+jJJVlTAFFbo87lao4qaQtHNxBSP8CmaRL8DcrQakUUUyq+zhnnYXhJsQxSzw7nBYrDxFqGCInNzYuDd3+OqHX5iZwBU70U+l9o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=IbgKruKo; 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="IbgKruKo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 05C411F000FF; Sat, 12 Sep 2026 18:39:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789238354; bh=VTfhQLdjPqC/hNscOQBiN2a9pCemvYAQnmKg+RuHxkY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IbgKruKoZAF9uCogB1zyJvPMyXVgE+0YCmUHzstSuP/fCXmBPaiNkoWp7GZaYw6Fj rqVlibt0zkuurowJtjwu4EgFm21epo6oOTKFO3BRQHU8WzZ/skRKi4ie+W0w8Qy2av lgm3gGnBye8B669XCJ/YIXOaM4Dk5nGE8kiczaLY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Gui-Dong Han , Hans Verkuil , Sasha Levin Subject: [PATCH 5.15 402/935] media: cec-pin: Fix event FIFO ordering Date: Sat, 12 Sep 2026 08:57:12 +0200 Message-ID: <20260912065536.044751570@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@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: Gui-Dong Han [ Upstream commit a1d83d1b810665bd53ce8a7b7867e054d68676c7 ] cec_pin_update() fills work_pin_events[] and work_pin_ts[], then increments work_pin_num_events. cec_pin_thread_func() uses that counter to decide when to read the FIFO entries. Do not let the counter update be observed without the event update. Also do not let a freed slot be reused before the thread has finished reading it. Use release operations when publishing an entry and releasing a slot, and acquire operations when consuming those counter updates. Leave the other work_pin_num_events users as they do not participate in this FIFO publication path. Fixes: ea5c8ef29668 ("media: cec-pin: add low-level pin hardware support") Signed-off-by: Gui-Dong Han Signed-off-by: Hans Verkuil Signed-off-by: Sasha Levin --- drivers/media/cec/core/cec-pin.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/media/cec/core/cec-pin.c b/drivers/media/cec/core/cec-pin.c index 99e69c49e0c9e..8e33e2b42dd46 100644 --- a/drivers/media/cec/core/cec-pin.c +++ b/drivers/media/cec/core/cec-pin.c @@ -114,7 +114,7 @@ static void cec_pin_update(struct cec_pin *pin, bool v, bool force) return; pin->adap->cec_pin_is_high = v; - if (atomic_read(&pin->work_pin_num_events) < CEC_NUM_PIN_EVENTS) { + if (atomic_read_acquire(&pin->work_pin_num_events) < CEC_NUM_PIN_EVENTS) { u8 ev = v; if (pin->work_pin_events_dropped) { @@ -125,7 +125,7 @@ static void cec_pin_update(struct cec_pin *pin, bool v, bool force) pin->work_pin_ts[pin->work_pin_events_wr] = ktime_get(); pin->work_pin_events_wr = (pin->work_pin_events_wr + 1) % CEC_NUM_PIN_EVENTS; - atomic_inc(&pin->work_pin_num_events); + atomic_inc_return_release(&pin->work_pin_num_events); } else { pin->work_pin_events_dropped = true; pin->work_pin_events_dropped_cnt++; @@ -1070,7 +1070,7 @@ static int cec_pin_thread_func(void *_adap) pin->work_tx_ts); } - while (atomic_read(&pin->work_pin_num_events)) { + while (atomic_read_acquire(&pin->work_pin_num_events)) { unsigned int idx = pin->work_pin_events_rd; u8 v = pin->work_pin_events[idx]; @@ -1079,7 +1079,7 @@ static int cec_pin_thread_func(void *_adap) v & CEC_PIN_EVENT_FL_DROPPED, pin->work_pin_ts[idx]); pin->work_pin_events_rd = (idx + 1) % CEC_NUM_PIN_EVENTS; - atomic_dec(&pin->work_pin_num_events); + atomic_dec_return_release(&pin->work_pin_num_events); } switch (atomic_xchg(&pin->work_irq_change, -- 2.53.0