linux-kernel - Re: [PATCH v3] HID: corsair-void: Update power supply values with a unified work handler

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Message-ID: <eae04827-0d87-48f5-929a-9f1f23359f24@kernel.org>
Date: Fri, 14 Feb 2025 07:34:54 +0100
From: Jiri Slaby <jirislaby@...nel.org>
To: Stuart Hayhurst <stuart.a.hayhurst@...il.com>, linux-input@...r.kernel.org
Cc: Jiri Kosina <jikos@...nel.org>, Benjamin Tissoires <bentiss@...nel.org>,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v3] HID: corsair-void: Update power supply values with a
 unified work handler

On 13. 02. 25, 14:38, Stuart Hayhurst wrote:
> corsair_void_process_receiver can be called from an interrupt context,
> locking battery_mutex in it was causing a kernel panic.
> Fix it by moving the critical section into its own work, sharing this
> work with battery_add_work and battery_remove_work to remove the need
> for any locking
> 
> Closes: https://bugzilla.suse.com/show_bug.cgi?id=1236843
> Fixes: 6ea2a6fd3872 ("HID: corsair-void: Add Corsair Void headset family driver")
> Cc: stable@...r.kernel.org
> Signed-off-by: Stuart Hayhurst <stuart.a.hayhurst@...il.com>

Reviewed-by: Jiri Slaby <jirislaby@...nel.org>

> ---
> 
> v2 -> v3:
>   - Use an enum instead of a define for battery flag values
>   - Use an integer instead of BIT() for the bit index

Good catch :).

>   - Drop unhelpful comments
>   - Simplify corsair_void_battery_work_handler logic
>   - Remove extra newline in commit message
> v1 -> v2:
>   - Actually remove the mutex
> 
> ---
>   drivers/hid/hid-corsair-void.c | 83 ++++++++++++++++++----------------
>   1 file changed, 43 insertions(+), 40 deletions(-)
> 
> diff --git a/drivers/hid/hid-corsair-void.c b/drivers/hid/hid-corsair-void.c
> index 56e858066c3c..afbd67aa9719 100644
> --- a/drivers/hid/hid-corsair-void.c
> +++ b/drivers/hid/hid-corsair-void.c
...
> @@ -583,16 +567,42 @@ static void corsair_void_battery_add_work_handler(struct work_struct *work)
>   	drvdata->battery = new_supply;
>   }
>   
> +static void corsair_void_battery_work_handler(struct work_struct *work)
> +{
> +	struct corsair_void_drvdata *drvdata = container_of(work,
> +		struct corsair_void_drvdata, battery_work);
> +
> +	bool add_battery = test_and_clear_bit(CORSAIR_VOID_ADD_BATTERY,
> +					      &drvdata->battery_work_flags);
> +	bool remove_battery = test_and_clear_bit(CORSAIR_VOID_REMOVE_BATTERY,
> +						 &drvdata->battery_work_flags);
> +	bool update_battery = test_and_clear_bit(CORSAIR_VOID_UPDATE_BATTERY,
> +						 &drvdata->battery_work_flags);
> +
> +	if (add_battery && !remove_battery) {
> +		corsair_void_add_battery(drvdata);
> +	} else if (remove_battery && !add_battery && drvdata->battery) {
> +		power_supply_unregister(drvdata->battery);
> +		drvdata->battery = NULL;
> +	}

Now I think, what is actually expected to happen if both add_battery and 
remove_battery is set? Do nothing as the code does?

> +	if (update_battery && drvdata->battery)
> +		power_supply_changed(drvdata->battery);
> +
> +}

thanks,
-- 
js
suse labs