Re: [PATCH] bus: mhi: core: replace snprintf with sysfs_emit

[Yihao Han]

On 2021/12/8 16:14, Greg Kroah-Hartman wrote:
> On Wed, Dec 08, 2021 at 12:07:53AM -0800, Yihao Han wrote:
> > coccinelle report:
> > ./drivers/bus/mhi/core/init.c:97:8-16:
> > WARNING: use scnprintf or sprintf
> > Use sysfs_emit instead of scnprintf or sprintf makes more sense.
> >
> > Signed-off-by: Yihao Han <hanyihao@xxxxxxxx>
> > ---
> >   drivers/bus/mhi/core/init.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> > index 5aaca6d0f52b..a5a5c722731e 100644
> > --- a/drivers/bus/mhi/core/init.c
> > +++ b/drivers/bus/mhi/core/init.c
> > @@ -94,7 +94,7 @@ static ssize_t serial_number_show(struct device *dev,
> >   	struct mhi_device *mhi_dev = to_mhi_device(dev);
> >   	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
> >   
> > -	return snprintf(buf, PAGE_SIZE, "Serial Number: %u\n",
> > +	return sysfs_emit(buf, "Serial Number: %u\n",
> >   			mhi_cntrl->serial_number);
> >   }
> >   static DEVICE_ATTR_RO(serial_number);
> > --
> > 2.17.1
>
> Why are you only changing one function in this file?  If you realyl want
> to make a change like this, fix ALL sysfs show functions.
>
> thanks,
>
> greg k-h
Because "sysfs_emit()" is "scnprintf()" equivalent with "size" parameter 
equals to PAGE_SIZE,So sysfs_emit can only be used here in this file. 
And "scnprintf" is better than "snprintf" because the former returns 
number of characters written to "buf". So I think we can use 
"sysfs_emit()" instead of "snprintf()".

Thanks,
Yihao