linux-kernel - Re: [PATCH v1 2/3] PCI/sysfs: Use PM runtime class macro for auto cleanup in reset_method

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Message-ID: <20250926144947.00002f75@huawei.com>
Date: Fri, 26 Sep 2025 14:49:47 +0100
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
CC: Linux PM <linux-pm@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>, "Alex Williamson"
	<alex.williamson@...hat.com>, Bjorn Helgaas <helgaas@...nel.org>, Takashi
 Iwai <tiwai@...e.de>, Zhang Qilong <zhangqilong3@...wei.com>, Ulf Hansson
	<ulf.hansson@...aro.org>, "Dan Williams" <dan.j.williams@...el.com>
Subject: Re: [PATCH v1 2/3] PCI/sysfs: Use PM runtime class macro for auto
 cleanup in reset_method_store()

On Fri, 19 Sep 2025 18:38:42 +0200
"Rafael J. Wysocki" <rafael@...nel.org> wrote:

> From: Takashi Iwai <tiwai@...e.de>
> 
> The newly introduced class macro can simplify the code.
> 
> Also, add the proper error handling for the PM runtime get.
> 
> Signed-off-by: Takashi Iwai <tiwai@...e.de>
> [ rjw: Adjust subject and error handling ]
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/pci/pci-sysfs.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -1475,8 +1475,9 @@ static ssize_t reset_method_store(struct
>  		return count;
>  	}
>  
> -	pm_runtime_get_sync(dev);
> -	struct device *pmdev __free(pm_runtime_put) = dev;
> +	CLASS(pm_runtime_resume_and_get, pmdev)(dev);
> +	if (IS_ERR(pmdev))
> +		return -ENXIO;
Hi Rafael,

Why this approach rather than treating runtime pm state like a conditional
lock (we use it much like one) and using ACQUIRE() / ACQUIRE_ERR()?

Ultimately that's a wrapper around the same infrastructure but
perhaps neater as it removes need to have that explicit magic pmdev.

+CC Dan as he can probably remember the discussions around ACQUIRE()
vs the way you have here better than I can.

In general great that you've done this.  Was on my list too, but I didn't
get around to actually spinning the patches!   This is going to be
very useful indeed.
 
Jonathan


>  
>  	if (sysfs_streq(buf, "default")) {
>  		pci_init_reset_methods(pdev);
> 
> 
> 
> 
>