linux-kernel - RE: [PATCH 12/59] Staging: hv: vmbus: Cleanup vmbus

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Date:	Thu, 25 Aug 2011 22:14:05 +0000
From:	KY Srinivasan <kys@...rosoft.com>
To:	Greg KH <greg@...ah.com>
CC:	"gregkh@...e.de" <gregkh@...e.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
	"virtualization@...ts.osdl.org" <virtualization@...ts.osdl.org>,
	Haiyang Zhang <haiyangz@...rosoft.com>
Subject: RE: [PATCH 12/59] Staging: hv: vmbus: Cleanup vmbus_uevent() code



> -----Original Message-----
> From: Greg KH [mailto:greg@...ah.com]
> Sent: Thursday, August 25, 2011 5:00 PM
> To: KY Srinivasan
> Cc: gregkh@...e.de; linux-kernel@...r.kernel.org;
> devel@...uxdriverproject.org; virtualization@...ts.osdl.org; Haiyang Zhang
> Subject: Re: [PATCH 12/59] Staging: hv: vmbus: Cleanup vmbus_uevent() code
> 
> On Thu, Aug 25, 2011 at 09:48:38AM -0700, K. Y. Srinivasan wrote:
> > Now generate appropriate uevent based on the modalias string. As part of this,
> > cleanup the existing uevent code.
> >
> > Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> > Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
> > ---
> >  drivers/staging/hv/vmbus_drv.c |   60 ++++++++--------------------------------
> >  1 files changed, 12 insertions(+), 48 deletions(-)
> >
> > diff --git a/drivers/staging/hv/vmbus_drv.c b/drivers/staging/hv/vmbus_drv.c
> > index b651968..a6e7dc5 100644
> > --- a/drivers/staging/hv/vmbus_drv.c
> > +++ b/drivers/staging/hv/vmbus_drv.c
> > @@ -237,58 +237,22 @@ static struct device_attribute vmbus_device_attrs[] =
> {
> >   * This routine is invoked when a device is added or removed on the vmbus to
> >   * generate a uevent to udev in the userspace. The udev will then look at its
> >   * rule and the uevent generated here to load the appropriate driver
> > + *
> > + * The alias string will be of the form vmbus:guid where guid is the string
> > + * representation of the device guid (each byte of the guid will be
> > + * represented with two hex characters.
> >   */
> >  static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
> >  {
> >  	struct hv_device *dev = device_to_hv_device(device);
> > -	int ret;
> > -
> > -	ret = add_uevent_var(env, "VMBUS_DEVICE_CLASS_GUID={"
> > -			     "%02x%02x%02x%02x-%02x%02x-%02x%02x-"
> > -			     "%02x%02x%02x%02x%02x%02x%02x%02x}",
> > -			     dev->dev_type.b[3],
> > -			     dev->dev_type.b[2],
> > -			     dev->dev_type.b[1],
> > -			     dev->dev_type.b[0],
> > -			     dev->dev_type.b[5],
> > -			     dev->dev_type.b[4],
> > -			     dev->dev_type.b[7],
> > -			     dev->dev_type.b[6],
> > -			     dev->dev_type.b[8],
> > -			     dev->dev_type.b[9],
> > -			     dev->dev_type.b[10],
> > -			     dev->dev_type.b[11],
> > -			     dev->dev_type.b[12],
> > -			     dev->dev_type.b[13],
> > -			     dev->dev_type.b[14],
> > -			     dev->dev_type.b[15]);
> > -
> > -	if (ret)
> > -		return ret;
> > +	int i, ret;
> > +	char alias_name[((sizeof(struct hv_vmbus_device_id) + 1)) * 2];
> >
> > -	ret = add_uevent_var(env, "VMBUS_DEVICE_DEVICE_GUID={"
> > -			     "%02x%02x%02x%02x-%02x%02x-%02x%02x-"
> > -			     "%02x%02x%02x%02x%02x%02x%02x%02x}",
> > -			     dev->dev_instance.b[3],
> > -			     dev->dev_instance.b[2],
> > -			     dev->dev_instance.b[1],
> > -			     dev->dev_instance.b[0],
> > -			     dev->dev_instance.b[5],
> > -			     dev->dev_instance.b[4],
> > -			     dev->dev_instance.b[7],
> > -			     dev->dev_instance.b[6],
> > -			     dev->dev_instance.b[8],
> > -			     dev->dev_instance.b[9],
> > -			     dev->dev_instance.b[10],
> > -			     dev->dev_instance.b[11],
> > -			     dev->dev_instance.b[12],
> > -			     dev->dev_instance.b[13],
> > -			     dev->dev_instance.b[14],
> > -			     dev->dev_instance.b[15]);
> > -	if (ret)
> > -		return ret;
> > +	for (i = 0; i < (sizeof(struct hv_vmbus_device_id) * 2); i += 2)
> > +		sprintf(&alias_name[i], "%02x", dev->dev_type.b[i/2]);
> 
> I have to edit this to get it to work properly with the fact that I
> added the driver_data field to hv_vmbus_device_id.
> 
> Arguably, one could say that this patch was always broken as you were
> assuming the size of an individual field was the same size as the whole
> structure, which I don't think is always the case, or at least it's not
> a safe thing to assume :)

Perhaps I could have sized it based on guid size since that is what is going
to be the alias. 

Regards,

K. Y

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