RE: [PATCH] devres: provide API devm_kstrndup

[Peng Fan]

Hi Greg,

> -----Original Message-----
> From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> Sent: 2023年5月4日 16:58
> To: Peng Fan (OSS) <peng.fan@xxxxxxxxxxx>
> Cc: robh+dt@xxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx;
> rafael@xxxxxxxxxx; andriy.shevchenko@xxxxxxxxxxxxxxx;
> hdegoede@xxxxxxxxxx; jgg@xxxxxxxx; saravanak@xxxxxxxxxx;
> keescook@xxxxxxxxxxxx; tglx@xxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> abel.vesa@xxxxxxxxxx; Peng Fan <peng.fan@xxxxxxx>
> Subject: Re: [PATCH] devres: provide API devm_kstrndup
> 
> On Thu, May 04, 2023 at 03:57:54PM +0800, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@xxxxxxx>
> >
> > This patch introduces devm_kstrndup API so that the device's driver
> > can allocate memory and copy string.
> >
> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > ---
> >  drivers/base/devres.c  | 28 ++++++++++++++++++++++++++++
> > include/linux/device.h |  1 +
> >  2 files changed, 29 insertions(+)
> 
> We can not add apis with no users, please submit this at the same time a
> driver needs it.
> 
> And what driver would need to copy a string?

https://lore.kernel.org/all/20230504085506.504474-1-peng.fan@xxxxxxxxxxx/

Should I submit V2 with the upper patch in a patchset?

Thanks,
Peng.

> 
> 
> >
> > diff --git a/drivers/base/devres.c b/drivers/base/devres.c index
> > 5c998cfac335..87e2965e5bab 100644
> > --- a/drivers/base/devres.c
> > +++ b/drivers/base/devres.c
> > @@ -963,6 +963,34 @@ char *devm_kstrdup(struct device *dev, const
> char
> > *s, gfp_t gfp)  }  EXPORT_SYMBOL_GPL(devm_kstrdup);
> >
> > +/**
> > + * devm_kstrndup - Allocate resource managed space and
> > + *                copy an existing string into that.
> > + * @dev: Device to allocate memory for
> > + * @s: the string to duplicate
> > + * @max: max length to duplicate
> > + * @gfp: the GFP mask used in the devm_kmalloc() call when allocating
> > +memory
> > + * RETURNS:
> > + * Pointer to allocated string on success, NULL on failure.
> > + */
> > +char *devm_kstrndup(struct device *dev, const char *s, size_t max,
> > +gfp_t gfp) {
> > +	size_t len;
> > +	char *buf;
> > +
> > +	if (!s)
> > +		return NULL;
> > +
> > +	len = strnlen(s, max);
> > +	buf = devm_kmalloc(dev, len + 1, gfp);
> > +	if (buf) {
> > +		memcpy(buf, s, len);
> > +		buf[len] = '\0';
> 
> Why not use kstrndup() instead of copying the same logic here?
> 
> thanks,
> 
> greg k-h