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([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-83965b333f2sm33057862b3a.20.2026.05.13.06.43.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 May 2026 06:43:24 -0700 (PDT) Sender: Guenter Roeck Message-ID: <5f0406fa-9692-49f0-bcfe-c013f5fc7b62@roeck-us.net> Date: Wed, 13 May 2026 06:43:23 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] hwmon: corsair-psu: fix and readd locking of command buffer To: Wilken Gottwalt , linux-kernel@vger.kernel.org Cc: linux-hwmon@vger.kernel.org References: Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAmgrMyQFCSbODQkACgkQyx8mb86fmYGcWRAA oRwrk7V8fULqnGGpBIjp7pvR187Yzx+lhMGUHuM5H56TFEqeVwCMLWB2x1YRolYbY4MEFlQg VUFcfeW0OknSr1s6wtrtQm0gdkolM8OcCL9ptTHOg1mmXa4YpW8QJiL0AVtbpE9BroeWGl9v 2TGILPm9mVp+GmMQgkNeCS7Jonq5f5pDUGumAMguWzMFEg+Imt9wr2YA7aGen7KPSqJeQPpj onPKhu7O/KJKkuC50ylxizHzmGx+IUSmOZxN950pZUFvVZH9CwhAAl+NYUtcF5ry/uSYG2U7 DCvpzqOryJRemKN63qt1bjF6cltsXwxjKOw6CvdjJYA3n6xCWLuJ6yk6CAy1Ukh545NhgBAs rGGVkl6TUBi0ixL3EF3RWLa9IMDcHN32r7OBhw6vbul8HqyTFZWY2ksTvlTl+qG3zV6AJuzT WdXmbcKN+TdhO5XlxVlbZoCm7ViBj1+PvIFQZCnLAhqSd/DJlhaq8fFXx1dCUPgQDcD+wo65 qulV/NijfU8bzFfEPgYP/3LP+BSAyFs33y/mdP8kbMxSCjnLEhimQMrSSo/To1Gxp5C97fw5 3m1CaMILGKCmfI1B8iA8zd8ib7t1Rg0qCwcAnvsM36SkrID32GfFbv873bNskJCHAISK3Xkz qo7IYZmjk/IJGbsiGzxUhvicwkgKE9r7a1rOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAmgrMyQFCSbODQkACgkQyx8mb86fmYHlgg/9 H5JeDmB4jsreE9Bn621wZk7NMzxy9STxiVKSh8Mq4pb+IDu1RU2iLyetCY1TiJlcxnE362kj njrfAdqyPteHM+LU59NtEbGwrfcXdQoh4XdMuPA5ADetPLma3YiRa3VsVkLwpnR7ilgwQw6u dycEaOxQ7LUXCs0JaGVVP25Z2hMkHBwx6BlW6EZLNgzGI2rswSZ7SKcsBd1IRHVf0miwIFYy j/UEfAFNW+tbtKPNn3xZTLs3quQN7GdYLh+J0XxITpBZaFOpwEKV+VS36pSLnNl0T5wm0E/y scPJ0OVY7ly5Vm1nnoH4licaU5Y1nSkFR/j2douI5P7Cj687WuNMC6CcFd6j72kRfxklOqXw zvy+2NEcXyziiLXp84130yxAKXfluax9sZhhrhKT6VrD45S6N3HxJpXQ/RY/EX35neH2/F7B RgSloce2+zWfpELyS1qRkCUTt1tlGV2p+y2BPfXzrHn2vxvbhEn1QpQ6t+85FKN8YEhJEygJ F0WaMvQMNrk9UAUziVcUkLU52NS9SXqpVg8vgrO0JKx97IXFPcNh0DWsSj/0Y8HO/RDkGXYn FDMj7fZSPKyPQPmEHg+W/KzxSSfdgWIHF2QaQ0b2q1wOSec4Rti52ohmNSY+KNIW/zODhugJ np3900V20aS7eD9K8GTU0TGC1pyz6IVJwIE= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/13/26 06:32, Wilken Gottwalt wrote: > Fix removed locking mechanism. The locking mechanism does protect > chained commands (set rail + get value), which are two separate calls > to the low level access function. The hwmon (temps for example) and > debugfs (uptimes for example) subsystem can trigger that chain of > commands in parallel. The serialization in the hw monioring core alone > is not enough. > > Fixes: 4207069edbf0 ("hwmon: (corsair-psu) Rely on subsystem locking") > Signed-off-by: Wilken Gottwalt You'll need to explain why using the subsystem lock for debugfs accesses does not work. Guenter > --- > drivers/hwmon/corsair-psu.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwmon/corsair-psu.c b/drivers/hwmon/corsair-psu.c > index 76f3e1da68d0..6db899b37ede 100644 > --- a/drivers/hwmon/corsair-psu.c > +++ b/drivers/hwmon/corsair-psu.c > @@ -12,6 +12,7 @@ > #include > #include > #include > +#include > #include > #include > > @@ -122,6 +123,7 @@ struct corsairpsu_data { > struct device *hwmon_dev; > struct dentry *debugfs; > struct completion wait_completion; > + struct mutex lock; /* serializes chained commands and parallel debugfs/hwmon access */ > u8 *cmd_buffer; > char vendor[REPLY_SIZE]; > char product[REPLY_SIZE]; > @@ -194,12 +196,14 @@ static int corsairpsu_init(struct corsairpsu_data *priv) > /* > * PSU_CMD_INIT uses swapped length/command and expects 2 parameter bytes, this command > * actually generates a reply, but we don't need it > + * only runs during probe/resume and does not switch rails, no locking required > */ > return corsairpsu_usb_cmd(priv, PSU_CMD_INIT, 3, 0, NULL); > } > > static int corsairpsu_fwinfo(struct corsairpsu_data *priv) > { > + /* only runs in probe and does not switch rails, no locking required */ > int ret; > > ret = corsairpsu_usb_cmd(priv, 3, PSU_CMD_VEND_STR, 0, priv->vendor); > @@ -217,6 +221,7 @@ static int corsairpsu_request(struct corsairpsu_data *priv, u8 cmd, u8 rail, voi > { > int ret; > > + mutex_lock(&priv->lock); > switch (cmd) { > case PSU_CMD_RAIL_VOLTS_HCRIT: > case PSU_CMD_RAIL_VOLTS_LCRIT: > @@ -226,13 +231,17 @@ static int corsairpsu_request(struct corsairpsu_data *priv, u8 cmd, u8 rail, voi > case PSU_CMD_RAIL_WATTS: > ret = corsairpsu_usb_cmd(priv, 2, PSU_CMD_SELECT_RAIL, rail, NULL); > if (ret < 0) > - return ret; > + goto cmd_fail; > break; > default: > break; > } > > - return corsairpsu_usb_cmd(priv, 3, cmd, 0, data); > + ret = corsairpsu_usb_cmd(priv, 3, cmd, 0, data); > + > +cmd_fail: > + mutex_unlock(&priv->lock); > + return ret; > } > > static int corsairpsu_get_value(struct corsairpsu_data *priv, u8 cmd, u8 rail, long *val) > @@ -789,6 +798,7 @@ static int corsairpsu_probe(struct hid_device *hdev, const struct hid_device_id > > priv->hdev = hdev; > hid_set_drvdata(hdev, priv); > + mutex_init(&priv->lock); > init_completion(&priv->wait_completion); > > hid_device_io_start(hdev);