linux-kernel - Re: [PATCH v1 2/2] PCI: Remove redundant probes for device reset support

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Date:   Mon, 19 Feb 2018 14:00:53 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     linux-pci@...r.kernel.org,
        Jayachandran Nair <Jayachandran.Nair@...ium.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        linux-kernel@...r.kernel.org,
        Alex Williamson <alex.williamson@...hat.com>,
        Robert Richter <Robert.Richter@...ium.com>,
        Tom Vaden <tom.vaden@....com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        George Cherian <george.cherian@...ium.com>
Subject: Re: [PATCH v1 2/2] PCI: Remove redundant probes for device reset support

On Friday, February 16, 2018 11:50:18 PM CET Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> We probe every device for whether it supports reset so we can tell whether
> to create a sysfs "reset" file for it.  We do that probe in
> pci_init_capabilities() during enumeration and save the result in
> dev->reset_fn.  The result doesn't depend on any other devices on the bus
> and shouldn't change after boot, so we don't need to do the probe again.
> 
> Remove the pci_probe_reset_function() calls and rely on the dev->reset_fn
> we found during enumeration.  No functional change intended.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>

Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  drivers/pci/pci.c |   15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index f6a4dd10d9b0..4db740e4f50a 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4450,9 +4450,8 @@ int pci_reset_function(struct pci_dev *dev)
>  {
>  	int rc;
>  
> -	rc = pci_probe_reset_function(dev);
> -	if (rc)
> -		return rc;
> +	if (!dev->reset_fn)
> +		return -ENOTTY;
>  
>  	pci_dev_lock(dev);
>  	pci_dev_save_and_disable(dev);
> @@ -4487,9 +4486,8 @@ int pci_reset_function_locked(struct pci_dev *dev)
>  {
>  	int rc;
>  
> -	rc = pci_probe_reset_function(dev);
> -	if (rc)
> -		return rc;
> +	if (!dev->reset_fn)
> +		return -ENOTTY;
>  
>  	pci_dev_save_and_disable(dev);
>  
> @@ -4511,9 +4509,8 @@ int pci_try_reset_function(struct pci_dev *dev)
>  {
>  	int rc;
>  
> -	rc = pci_probe_reset_function(dev);
> -	if (rc)
> -		return rc;
> +	if (!dev->reset_fn)
> +		return -ENOTTY;
>  
>  	if (!pci_dev_trylock(dev))
>  		return -EAGAIN;
> 
>