diff mbox series

[v8,4/8] PCI/sysfs: Allow userspace to query and set device reset mechanism

Message ID 20210629160104.2893-5-ameynarkhede03@gmail.com (mailing list archive)
State Superseded
Delegated to: Bjorn Helgaas
Headers show
Series Expose and manage PCI device reset | expand

Commit Message

ameynarkhede03 June 29, 2021, 4:01 p.m. UTC 
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>
---
 Documentation/ABI/testing/sysfs-bus-pci |  19 +++++
 drivers/pci/pci-sysfs.c                 | 102 ++++++++++++++++++++++++
 drivers/pci/pci.c                       |   1 +
 3 files changed, 122 insertions(+)

Comments

Alex Williamson June 30, 2021, 6:49 p.m. UTC | #1 
On Tue, 29 Jun 2021 21:31:00 +0530
Amey Narkhede <ameynarkhede03@gmail.com> 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>
> ---
>  Documentation/ABI/testing/sysfs-bus-pci |  19 +++++
>  drivers/pci/pci-sysfs.c                 | 102 ++++++++++++++++++++++++
>  drivers/pci/pci.c                       |   1 +
>  3 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..6713af211 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -1334,6 +1334,107 @@ 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,
> +				 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)

Given the new encoding, shouldn't this be:

	if (!idx)
		break;

For example if we had [1, 0, 2,...] (which should be impossible) then
__pci_reset_function_locked() would stop at the first zero, but the
logic here would cause sysfs to print "device_specific,flr".

> +			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,
> +				  struct device_attribute *attr,
> +				  const char *buf, size_t count)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +	int i, n;
> +	char *name, *options;
> +	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");
> +		memset(pdev->reset_methods, 0, PCI_NUM_RESET_METHODS);

If options were initialized to NULL, this could be a goto before the
memcpy below.

> +		return count;
> +	}
> +
> +	if (sysfs_streq(buf, "default")) {
> +		pci_init_reset_methods(pdev);
> +		return count;
> +	}
> +
> +	options = kstrndup(buf, count, GFP_KERNEL);
> +	if (!options)
> +		return -ENOMEM;
> +
> +	n = 0;

nit, initialize in declaration.  Looks like @i could also be scoped
within the below loop.

> +
> +	while ((name = strsep(&options, ",")) != NULL) {
> +		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");
> +
> +	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,
> +						    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,
>  			   const char *buf, size_t count)
>  {
> @@ -1491,6 +1592,7 @@ 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,
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 90f0b35e6..db4e035cf 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5198,6 +5198,7 @@ void pci_init_reset_methods(struct pci_dev *dev)
>  		else if (rc != -ENOTTY)
>  			break;
>  	}
> +
>  	memcpy(dev->reset_methods, reset_methods, sizeof(reset_methods));
>  }
>  

Do this cleanup where it was introduced in patch 2/  Thanks,

Alex
diff mbox series

Patch

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..6713af211 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1334,6 +1334,107 @@  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,
+				 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)
+			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,
+				  struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	int i, n;
+	char *name, *options;
+	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");
+		memset(pdev->reset_methods, 0, PCI_NUM_RESET_METHODS);
+		return count;
+	}
+
+	if (sysfs_streq(buf, "default")) {
+		pci_init_reset_methods(pdev);
+		return count;
+	}
+
+	options = kstrndup(buf, count, GFP_KERNEL);
+	if (!options)
+		return -ENOMEM;
+
+	n = 0;
+
+	while ((name = strsep(&options, ",")) != NULL) {
+		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");
+
+	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,
+						    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,
 			   const char *buf, size_t count)
 {
@@ -1491,6 +1592,7 @@  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,
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 90f0b35e6..db4e035cf 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5198,6 +5198,7 @@  void pci_init_reset_methods(struct pci_dev *dev)
 		else if (rc != -ENOTTY)
 			break;
 	}
+
 	memcpy(dev->reset_methods, reset_methods, sizeof(reset_methods));
 }