Linux Virtualization - Sep 2011 - [PATCH] Staging: hv: vmbus: Show the modalias in /sys/bus/vmbus/devices/*/

Show a modalias file in /sys/bus/vmbus/devices/*/
Add a helper function to print the same content in modalias and uevent.

Signed-off-by: Olaf Hering <olaf at aepfle.de>

---
 drivers/staging/hv/vmbus_drv.c |   21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

--- a/drivers/staging/hv/vmbus_drv.c
+++ b/drivers/staging/hv/vmbus_drv.c
@@ -93,6 +93,14 @@ static void get_channel_info(struct hv_d
 		debug_info.outbound.bytes_avail_towrite;
 }
 
+#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid) * 2)
+static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
+{
+	int i;
+	for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
+		sprintf(&alias_name[i], "%02x", hv_dev->dev_type.b[i/2]);
+}
+
 /*
  * vmbus_show_device_attr - Show the device attribute in sysfs.
  *
@@ -105,6 +113,7 @@ static ssize_t vmbus_show_device_attr(st
 {
 	struct hv_device *hv_dev = device_to_hv_device(dev);
 	struct hv_device_info device_info;
+	char alias_name[VMBUS_ALIAS_LEN + 1];
 
 	memset(&device_info, 0, sizeof(struct hv_device_info));
 
@@ -148,6 +157,9 @@ static ssize_t vmbus_show_device_attr(st
 			       device_info.chn_instance.b[13],
 			       device_info.chn_instance.b[14],
 			       device_info.chn_instance.b[15]);
+	} else if (!strcmp(dev_attr->attr.name, "modalias")) {
+		print_alias_name(hv_dev, alias_name);
+		return sprintf(buf, "vmbus:%s\n", alias_name);
 	} else if (!strcmp(dev_attr->attr.name, "state")) {
 		return sprintf(buf, "%d\n", device_info.chn_state);
 	} else if (!strcmp(dev_attr->attr.name, "id")) {
@@ -204,6 +216,7 @@ static struct device_attribute vmbus_dev
 	__ATTR(class_id, S_IRUGO, vmbus_show_device_attr, NULL),
 	__ATTR(device_id, S_IRUGO, vmbus_show_device_attr, NULL),
 	__ATTR(monitor_id, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(modalias, S_IRUGO, vmbus_show_device_attr, NULL),
 
 	__ATTR(server_monitor_pending, S_IRUGO, vmbus_show_device_attr, NULL),
 	__ATTR(server_monitor_latency, S_IRUGO, vmbus_show_device_attr, NULL),
@@ -242,12 +255,10 @@ static struct device_attribute vmbus_dev
 static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
 {
 	struct hv_device *dev = device_to_hv_device(device);
-	int i, ret;
-	char alias_name[((sizeof((struct hv_vmbus_device_id *)0)->guid) + 1) * 2];
-
-	for (i = 0; i < ((sizeof((struct hv_vmbus_device_id *)0)->guid) * 2); i
+= 2)
-		sprintf(&alias_name[i], "%02x", dev->dev_type.b[i/2]);
+	int ret;
+	char alias_name[VMBUS_ALIAS_LEN + 1];
 
+	print_alias_name(dev, alias_name);
 	ret = add_uevent_var(env, "MODALIAS=vmbus:%s", alias_name);
 	return ret;
 }

On Fri, Sep 02, 2011 at 06:25:56PM +0200, Olaf Hering
wrote:
> Show a modalias file in /sys/bus/vmbus/devices/*/
> Add a helper function to print the same content in modalias and uevent.
> 
> Signed-off-by: Olaf Hering <olaf at aepfle.de>
Nice idea, thanks for this, one minor nit below:
> ---
>  drivers/staging/hv/vmbus_drv.c |   21 ++++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
> 
> --- a/drivers/staging/hv/vmbus_drv.c
> +++ b/drivers/staging/hv/vmbus_drv.c
> @@ -93,6 +93,14 @@ static void get_channel_info(struct hv_d
>  		debug_info.outbound.bytes_avail_towrite;
>  }
>  
> +#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid)
* 2)
> +static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
> +{
> +	int i;
> +	for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
> +		sprintf(&alias_name[i], "%02x",
hv_dev->dev_type.b[i/2]);
> +}
> +
>  /*
>   * vmbus_show_device_attr - Show the device attribute in sysfs.
>   *
> @@ -105,6 +113,7 @@ static ssize_t vmbus_show_device_attr(st
>  {
>  	struct hv_device *hv_dev = device_to_hv_device(dev);
>  	struct hv_device_info device_info;
> +	char alias_name[VMBUS_ALIAS_LEN + 1];
Is that too big to put on the stack?  64 bytes, right?  Hm, maybe not.

Wait, hv_device_info is huge, that should be dynamic in the first place.
Olaf, not your issue, but KY, want to fix that up?

thanks,

greg k-h

On Fri, Sep 02, Greg KH wrote:
> On Fri, Sep 02, 2011 at 06:25:56PM +0200, Olaf Hering wrote:
> > +#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id
*)0)->guid) * 2)
> > +	char alias_name[VMBUS_ALIAS_LEN + 1];
> 
> Is that too big to put on the stack?  64 bytes, right?  Hm, maybe not.
16 * 2 + 1 = 33 bytes.

Olaf

> -----Original Message-----
> From: Olaf Hering [mailto:olaf at aepfle.de]
> Sent: Friday, September 02, 2011 12:26 PM
> To: KY Srinivasan
> Cc: gregkh at suse.de; linux-kernel at vger.kernel.org;
> devel at linuxdriverproject.org; virtualization at lists.osdl.org
> Subject: [PATCH] Staging: hv: vmbus: Show the modalias in
> /sys/bus/vmbus/devices/*/
> 
> Show a modalias file in /sys/bus/vmbus/devices/*/
> Add a helper function to print the same content in modalias and uevent.
> 
> Signed-off-by: Olaf Hering <olaf at aepfle.de>
> 
> ---
>  drivers/staging/hv/vmbus_drv.c |   21 ++++++++++++++++-----
>  1 file changed, 16 insertions(+), 5 deletions(-)
> 
> --- a/drivers/staging/hv/vmbus_drv.c
> +++ b/drivers/staging/hv/vmbus_drv.c
> @@ -93,6 +93,14 @@ static void get_channel_info(struct hv_d
>  		debug_info.outbound.bytes_avail_towrite;
>  }
> 
> +#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid)
*
> 2)
> +static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
> +{
> +	int i;
> +	for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
> +		sprintf(&alias_name[i], "%02x",
hv_dev->dev_type.b[i/2]);
> +}
> +
>  /*
>   * vmbus_show_device_attr - Show the device attribute in sysfs.
>   *
> @@ -105,6 +113,7 @@ static ssize_t vmbus_show_device_attr(st
>  {
>  	struct hv_device *hv_dev = device_to_hv_device(dev);
>  	struct hv_device_info device_info;
> +	char alias_name[VMBUS_ALIAS_LEN + 1];
> 
>  	memset(&device_info, 0, sizeof(struct hv_device_info));
> 
> @@ -148,6 +157,9 @@ static ssize_t vmbus_show_device_attr(st
>  			       device_info.chn_instance.b[13],
>  			       device_info.chn_instance.b[14],
>  			       device_info.chn_instance.b[15]);
> +	} else if (!strcmp(dev_attr->attr.name, "modalias")) {
> +		print_alias_name(hv_dev, alias_name);
> +		return sprintf(buf, "vmbus:%s\n", alias_name);
>  	} else if (!strcmp(dev_attr->attr.name, "state")) {
>  		return sprintf(buf, "%d\n", device_info.chn_state);
>  	} else if (!strcmp(dev_attr->attr.name, "id")) {
> @@ -204,6 +216,7 @@ static struct device_attribute vmbus_dev
>  	__ATTR(class_id, S_IRUGO, vmbus_show_device_attr, NULL),
>  	__ATTR(device_id, S_IRUGO, vmbus_show_device_attr, NULL),
>  	__ATTR(monitor_id, S_IRUGO, vmbus_show_device_attr, NULL),
> +	__ATTR(modalias, S_IRUGO, vmbus_show_device_attr, NULL),
> 
>  	__ATTR(server_monitor_pending, S_IRUGO, vmbus_show_device_attr,
> NULL),
>  	__ATTR(server_monitor_latency, S_IRUGO, vmbus_show_device_attr,
> NULL),
> @@ -242,12 +255,10 @@ static struct device_attribute vmbus_dev
>  static int vmbus_uevent(struct device *device, struct kobj_uevent_env
*env)
>  {
>  	struct hv_device *dev = device_to_hv_device(device);
> -	int i, ret;
> -	char alias_name[((sizeof((struct hv_vmbus_device_id *)0)->guid) + 1) *
> 2];
> -
> -	for (i = 0; i < ((sizeof((struct hv_vmbus_device_id *)0)->guid) *
2); i += 2)
> -		sprintf(&alias_name[i], "%02x", dev->dev_type.b[i/2]);
> +	int ret;
> +	char alias_name[VMBUS_ALIAS_LEN + 1];
> 
> +	print_alias_name(dev, alias_name);
>  	ret = add_uevent_var(env, "MODALIAS=vmbus:%s", alias_name);
>  	return ret;
>  }
Acked-by:  K. Y. Srinivasan <kys at microsoft.com>