From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 B0DD619343B; Mon, 6 Jan 2025 09:38:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736156333; cv=none; b=UaI7JlGmvHyitcu4VrzrmGk5UliKT8hMuLD6wo+PCioKtHwuLiU1fM+uaQWBQAB6bMw5/MrNtkjf+7dwAm7WWyOoUsMNXqYQwaRYoYrADyWlvQFAGsLCdPLDgsqSJ8UYA7dLcuzFbPQ3GWaAMaxfpbqxx8FlCDFIPTz5Hz8boCw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736156333; c=relaxed/simple; bh=wXUDSC+KjmeORBaO11pq0QSTWrOACZqdIZWgNf632kQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=egkyuPiuD5jmMyJHZmyTyVUdCdEWZF1NvDJQBAVFM3yLyyHaK/G+O1g7nAa/qMB4g2ZybpKY7/Ljp1vxwl5ZPXnk4XP14S/2HGeN4W9OnLJR+/deg/6kJQs/UAScLi7+xkLKV6AOctsEpzPg4SUiG8M/FjgGNjUciwP9AgExjgI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=eq2udhdt; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="eq2udhdt" Received: from [192.168.88.20] (91-158-153-178.elisa-laajakaista.fi [91.158.153.178]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 7C3EC2A5; Mon, 6 Jan 2025 10:37:55 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1736156276; bh=wXUDSC+KjmeORBaO11pq0QSTWrOACZqdIZWgNf632kQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=eq2udhdtCfCH1HeSr51HV1Yp6tcXuy0k+3rBaYuenpdPmMPinXdVBNCWhsqro5MuH ryS8Sqa1gRcVG1pe4d3kZOFnGjhh6KzdxWS/6hc8p3sn4b14oKWdKtJc9JXt7gbsPn ztnCtxX1NIhOmp84B0aX50/YjjfFhlHetmSUOWmE= Message-ID: <73dd31df-cce6-445e-bf69-67b9854e9444@ideasonboard.com> Date: Mon, 6 Jan 2025 11:38:43 +0200 Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 3/9] media: i2c: ds90ub960: Protect alias_use_mask with a mutex To: Romain Gantois Cc: Thomas Petazzoni , Kory Maincent , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-media@vger.kernel.org, linux-gpio@vger.kernel.org, Wolfram Sang , Luca Ceresoli , Andi Shyti , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Derek Kiernan , Dragan Cvetic , Arnd Bergmann , Greg Kroah-Hartman , Mauro Carvalho Chehab , Linus Walleij , Bartosz Golaszewski References: <20241230-fpc202-v4-0-761b297dc697@bootlin.com> <20241230-fpc202-v4-3-761b297dc697@bootlin.com> Content-Language: en-US From: Tomi Valkeinen Autocrypt: addr=tomi.valkeinen@ideasonboard.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 30/12/2024 15:22, Romain Gantois wrote: > The aliased_addrs list represents the occupation of an RX port's hardware > alias table. This list and the underlying hardware table are only accessed > in the attach/detach_client() callbacks. > > These functions are only called from a bus notifier handler in i2c-atr.c, > which is always called with the notifier chain's semaphore held. This > indirectly prevents concurrent access to the aliased_addrs list. > However, more explicit and direct locking is preferable. Moreover, with the > introduction of dynamic address translation in a future patch, the > attach/detach_client() callbacks will be called from outside of the > notifier chain's read section. > > Introduce a mutex to protect access to the aliased_addrs list and its > underlying hardware table. > > Signed-off-by: Romain Gantois > --- > drivers/media/i2c/ds90ub960.c | 23 ++++++++++++++++++++--- > 1 file changed, 20 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c > index 7534ddf2079fef466d3a114f0be98599427639fa..0510427ac4e9214132bcdf3fa18873ec78c48a5e 100644 > --- a/drivers/media/i2c/ds90ub960.c > +++ b/drivers/media/i2c/ds90ub960.c > @@ -467,6 +467,8 @@ struct ub960_rxport { > }; > } eq; > > + /* lock for aliased_addrs and associated registers */ > + struct mutex aliased_addrs_lock; > u16 aliased_addrs[UB960_MAX_PORT_ALIASES]; > }; > > @@ -1030,6 +1032,9 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id, > struct ub960_rxport *rxport = priv->rxports[chan_id]; > struct device *dev = &priv->client->dev; > unsigned int reg_idx; > + int ret = 0; > + > + mutex_lock(&rxport->aliased_addrs_lock); A mutex guard could be used here and below. Tomi > > for (reg_idx = 0; reg_idx < UB960_MAX_PORT_ALIASES; reg_idx++) { > if (!rxport->aliased_addrs[reg_idx]) > @@ -1038,7 +1043,8 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id, > > if (reg_idx == UB960_MAX_PORT_ALIASES) { > dev_err(dev, "rx%u: alias pool exhausted\n", rxport->nport); > - return -EADDRNOTAVAIL; > + ret = -EADDRNOTAVAIL; > + goto out_unlock; > } > > rxport->aliased_addrs[reg_idx] = client->addr; > @@ -1051,7 +1057,9 @@ static int ub960_atr_attach_client(struct i2c_atr *atr, u32 chan_id, > dev_dbg(dev, "rx%u: client 0x%02x assigned alias 0x%02x at slot %u\n", > rxport->nport, client->addr, alias, reg_idx); > > - return 0; > +out_unlock: > + mutex_unlock(&rxport->aliased_addrs_lock); > + return ret; > } > > static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, > @@ -1062,6 +1070,8 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, > struct device *dev = &priv->client->dev; > unsigned int reg_idx; > > + mutex_lock(&rxport->aliased_addrs_lock); > + > for (reg_idx = 0; reg_idx < UB960_MAX_PORT_ALIASES; reg_idx++) { > if (rxport->aliased_addrs[reg_idx] == client->addr) > break; > @@ -1070,7 +1080,7 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, > if (reg_idx == UB960_MAX_PORT_ALIASES) { > dev_err(dev, "rx%u: client 0x%02x is not mapped!\n", > rxport->nport, client->addr); > - return; > + goto out_unlock; > } > > rxport->aliased_addrs[reg_idx] = 0; > @@ -1079,6 +1089,9 @@ static void ub960_atr_detach_client(struct i2c_atr *atr, u32 chan_id, > > dev_dbg(dev, "rx%u: client 0x%02x released at slot %u\n", rxport->nport, > client->addr, reg_idx); > + > +out_unlock: > + mutex_unlock(&rxport->aliased_addrs_lock); > } > > static const struct i2c_atr_ops ub960_atr_ops = { > @@ -3181,6 +3194,8 @@ static void ub960_rxport_free_ports(struct ub960_data *priv) > fwnode_handle_put(rxport->source.ep_fwnode); > fwnode_handle_put(rxport->ser.fwnode); > > + mutex_destroy(&rxport->aliased_addrs_lock); > + > kfree(rxport); > priv->rxports[nport] = NULL; > } > @@ -3401,6 +3416,8 @@ static int ub960_parse_dt_rxport(struct ub960_data *priv, unsigned int nport, > if (ret) > goto err_put_remote_fwnode; > > + mutex_init(&rxport->aliased_addrs_lock); > + > return 0; > > err_put_remote_fwnode: >