linux-kernel - Re: [PATCH v4 2/3] PCI/sysfs: Use runtime PM guard macro for auto-cleanup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <25435d82-575d-495f-ae61-bd38570ff9ad@linux.ibm.com>
Date: Mon, 20 Oct 2025 15:07:01 -0700
From: Farhan Ali <alifm@...ux.ibm.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        Bjorn Helgaas <helgaas@...nel.org>
Cc: Takashi Iwai <tiwai@...e.de>, LKML <linux-kernel@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Zhang Qilong <zhangqilong3@...wei.com>,
        Ulf Hansson
 <ulf.hansson@...aro.org>, Frank Li <Frank.Li@....com>,
        Dhruva Gole <d-gole@...com>, Niklas Schnelle <schnelle@...ux.ibm.com>
Subject: Re: [PATCH v4 2/3] PCI/sysfs: Use runtime PM guard macro for
 auto-cleanup


On 9/26/2025 9:24 AM, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> Use the newly introduced pm_runtime_active_try guard to simplify
> the code and add the proper error handling for PM runtime resume
> errors.
>
> Based on an earlier patch from Takashi Iwai <tiwai@...e.de> [1].
>
> Link: https://patch.msgid.link/20250919163147.4743-3-tiwai@suse.de [1]
> Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>
> v3 -> v4:
>     * Use ACQUIRE()/ACQUIRE_ERR() (Jonathan)
>     * Adjust subject and changelog
>     * Take patch ownership (it's all different now)
>     * Pick up Bjorn's ACK from v3 (Bjorn, please let me know if that's not OK)
>
> v2 -> v3: No changes
>
> v1 -> v2:
>     * Adjust the name of the class to handle the disabled runtime PM case
>       transparently (like the original code).
>
> ---
>   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;
> +	ACQUIRE(pm_runtime_active_try, pm)(dev);
> +	if (ACQUIRE_ERR(pm_runtime_active_try, &pm))
> +		return -ENXIO;
>   
>   	if (sysfs_streq(buf, "default")) {
>   		pci_init_reset_methods(pdev);
>
>
Hi Rafael,

This patch breaks updating the 'reset_method' sysfs file on s390. If we 
try to update the reset_method, we are hitting the ENXIO error. eg:

echo 'bus' > /sys/bus/pci/devices/0007\:00\:10.1/reset_method
-bash: echo: write error: No such device or address

I don't think s390 does anything different in this path, so this could 
also impact other platforms? Changing this to something like this fixes it


diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 9d6f74bd95f8..d7fc0dc81c30 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1517,8 +1517,8 @@ static ssize_t reset_method_store(struct device *dev,
                 return count;
         }

-       ACQUIRE(pm_runtime_active_try, pm)(dev);
-       if (ACQUIRE_ERR(pm_runtime_active_try, &pm))
+       ACQUIRE(pm_runtime_active, pm)(dev);
+       if (ACQUIRE_ERR(pm_runtime_active, &pm))
                 return -ENXIO;

This changes the logic to what it was previously which used 
pm_runtime_get_sync and pm_runtime_put. But I am not familiar with the 
PM runtime code, so not sure what would be the right fix here.

Thanks

Farhan