Re: [PATCH v9 4/8] PCI/sysfs: Allow userspace to query and set device reset mechanism

[Amey Narkhede <ameynarkhede03@gmail.com>]

On 21/07/11 04:51PM, Raphael Norwitz wrote:
> On Mon, Jul 05, 2021 at 07:51:34PM +0530, Amey Narkhede wrote:
> > Add reset_method sysfs attribute to enable user to query and set user
> > preferred device reset methods and their ordering.
> >
> > Co-developed-by: Alex Williamson <alex.williamson@redhat.com>
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
>
> Just some spacing NITs.
>
> Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
>
> > ---
> >  Documentation/ABI/testing/sysfs-bus-pci |  19 +++++
> >  drivers/pci/pci-sysfs.c                 | 103 ++++++++++++++++++++++++
> >  2 files changed, 122 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
> > index ef00fada2..43f4e33c7 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-pci
> > +++ b/Documentation/ABI/testing/sysfs-bus-pci
> > @@ -121,6 +121,25 @@ Description:
> >  		child buses, and re-discover devices removed earlier
> >  		from this part of the device tree.
> >
> > +What:		/sys/bus/pci/devices/.../reset_method
> > +Date:		March 2021
> > +Contact:	Amey Narkhede <ameynarkhede03@gmail.com>
> > +Description:
> > +		Some devices allow an individual function to be reset
> > +		without affecting other functions in the same slot.
> > +
> > +		For devices that have this support, a file named
> > +		reset_method will be present in sysfs. Initially reading
> > +		this file will give names of the device supported reset
> > +		methods and their ordering. After write, this file will
> > +		give names and ordering of currently enabled reset methods.
> > +		Writing the name or comma separated list of names of any of
> > +		the device supported reset methods to this file will set
> > +		the reset methods and their ordering to be used when
> > +		resetting the device. Writing empty string to this file
> > +		will disable ability to reset the device and writing
> > +		"default" will return to the original value.
> > +
> >  What:		/sys/bus/pci/devices/.../reset
> >  Date:		July 2009
> >  Contact:	Michael S. Tsirkin <mst@redhat.com>
> > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> > index 316f70c3e..8a740e211 100644
> > --- a/drivers/pci/pci-sysfs.c
> > +++ b/drivers/pci/pci-sysfs.c
> > @@ -1334,6 +1334,108 @@ static const struct attribute_group pci_dev_rom_attr_group = {
> >  	.is_bin_visible = pci_dev_rom_attr_is_visible,
> >  };
> >
> > +static ssize_t reset_method_show(struct device *dev,
>
> Nit: spaces on the following two lines. "struct device_attribute *attr"
> and "char *buf" should be in line with "struct device *dev"
>
Not sure what happened when creating the patches but on my editor spaces
seems to consistent as you suggested here. For some reason git
format-patch is acting weird.

Thanks,
Amey
> > +				 struct device_attribute *attr,
> > +				 char *buf)
> > +{
> > +	struct pci_dev *pdev = to_pci_dev(dev);
> > +	ssize_t len = 0;
> > +	int i, idx;
> > +
> > +	for (i = 0; i < PCI_NUM_RESET_METHODS; i++) {
> > +		idx = pdev->reset_methods[i];
> > +		if (!idx)
> > +			break;
> > +
> > +		len += sysfs_emit_at(buf, len, "%s%s", len ? "," : "",
> > +				     pci_reset_fn_methods[idx].name);
> > +	}
> > +
> > +	if (len)
> > +		len += sysfs_emit_at(buf, len, "\n");
> > +
> > +	return len;
> > +}
> > +
> > +static ssize_t reset_method_store(struct device *dev,
>
> Nit: spaces on the following two lines
>
> > +				  struct device_attribute *attr,
> > +				  const char *buf, size_t count)
> > +{
> > +	struct pci_dev *pdev = to_pci_dev(dev);
> > +	int n = 0;
> > +	char *name, *options = NULL;
> > +	u8 reset_methods[PCI_NUM_RESET_METHODS] = { 0 };
> > +
> > +	if (count >= (PAGE_SIZE - 1))
> > +		return -EINVAL;
> > +
> > +	if (sysfs_streq(buf, "")) {
> > +		pci_warn(pdev, "All device reset methods disabled by user");
> > +		goto set_reset_methods;
> > +	}
> > +
> > +	if (sysfs_streq(buf, "default")) {
> > +		pci_init_reset_methods(pdev);
> > +		return count;
> > +	}
> > +
> > +	options = kstrndup(buf, count, GFP_KERNEL);
> > +	if (!options)
> > +		return -ENOMEM;
> > +
> > +	while ((name = strsep(&options, ",")) != NULL) {
> > +		int i;
> > +
> > +		if (sysfs_streq(name, ""))
> > +			continue;
> > +
> > +		name = strim(name);
> > +
> > +		for (i = 1; i < PCI_NUM_RESET_METHODS; i++) {
> > +			if (sysfs_streq(name, pci_reset_fn_methods[i].name) &&
> > +			    !pci_reset_fn_methods[i].reset_fn(pdev, 1)) {
> > +				reset_methods[n++] = i;
> > +				break;
> > +			}
> > +		}
> > +
> > +		if (i == PCI_NUM_RESET_METHODS) {
> > +			kfree(options);
> > +			return -EINVAL;
> > +		}
> > +	}
> > +
> > +	if (!pci_reset_fn_methods[1].reset_fn(pdev, 1) && reset_methods[0] != 1)
> > +		pci_warn(pdev, "Device specific reset disabled/de-prioritized by user");
> > +
> > +set_reset_methods:
> > +	memcpy(pdev->reset_methods, reset_methods, sizeof(reset_methods));
> > +	kfree(options);
> > +	return count;
> > +}
> > +static DEVICE_ATTR_RW(reset_method);
> > +
> > +static struct attribute *pci_dev_reset_method_attrs[] = {
> > +	&dev_attr_reset_method.attr,
> > +	NULL,
> > +};
> > +
> > +static umode_t pci_dev_reset_method_attr_is_visible(struct kobject *kobj,
>
> Nit: ditto - spacing.
>
> > +						    struct attribute *a, int n)
> > +{
> > +	struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
> > +
> > +	if (!pci_reset_supported(pdev))
> > +		return 0;
> > +
> > +	return a->mode;
> > +}
> > +
> > +static const struct attribute_group pci_dev_reset_method_attr_group = {
> > +	.attrs = pci_dev_reset_method_attrs,
> > +	.is_visible = pci_dev_reset_method_attr_is_visible,
> > +};
> > +
> >  static ssize_t reset_store(struct device *dev, struct device_attribute *attr,
>
> Nit: spacing following line.
>
> >  			   const char *buf, size_t count)
> >  {
> > @@ -1491,6 +1593,7 @@ const struct attribute_group *pci_dev_groups[] = {
> >  	&pci_dev_config_attr_group,
> >  	&pci_dev_rom_attr_group,
> >  	&pci_dev_reset_attr_group,
> > +	&pci_dev_reset_method_attr_group,
> >  	&pci_dev_vpd_attr_group,
> >  #ifdef CONFIG_DMI
> >  	&pci_dev_smbios_attr_group,
> > --
> > 2.32.0
> >
> >