Re: [PATCH v3 1/2] pci: endpoint: Simplify name allocation for epf device

From: Rolf Evers-Fischer
Date: Tue Feb 27 2018 - 05:16:19 EST


Hi,

On Tue, 27 Feb 2018, Kishon Vijay Abraham I wrote:

> Hi,
>
> On Tuesday 27 February 2018 03:32 PM, Rolf Evers-Fischer wrote:
> > From: Rolf Evers-Fischer <rolf.evers.fischer@xxxxxxxxx>
> >
> > This commit replaces allocating and freeing the intermediate
> > 'buf'/'func_name' with a combination of 'kstrndup()' and 'len'.
> >
> > 'len' is the required length of 'epf->name'.
> > 'epf->name' should be either the first part of 'name' preceding the '.'
> > or the complete 'name', if there is no '.' in the name.
> >
> > Signed-off-by: Rolf Evers-Fischer <rolf.evers.fischer@xxxxxxxxx>
> > ---
> > drivers/pci/endpoint/pci-epf-core.c | 22 ++++------------------
> > 1 file changed, 4 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c
> > index 766ce1dca2ec..1f2506f32bb9 100644
> > --- a/drivers/pci/endpoint/pci-epf-core.c
> > +++ b/drivers/pci/endpoint/pci-epf-core.c
> > @@ -200,8 +200,7 @@ struct pci_epf *pci_epf_create(const char *name)
> > int ret;
> > struct pci_epf *epf;
> > struct device *dev;
> > - char *func_name;
> > - char *buf;
> > + int len;
> >
> > epf = kzalloc(sizeof(*epf), GFP_KERNEL);
> > if (!epf) {
> > @@ -209,20 +208,11 @@ struct pci_epf *pci_epf_create(const char *name)
> > goto err_ret;
> > }
> >
> > - buf = kstrdup(name, GFP_KERNEL);
> > - if (!buf) {
> > - ret = -ENOMEM;
> > - goto free_epf;
> > - }
> > -
> > - func_name = buf;
> > - buf = strchrnul(buf, '.');
> > - *buf = '\0';
> > -
> > - epf->name = kstrdup(func_name, GFP_KERNEL);
> > + len = strchrnul(name, '.') - name;
> > + epf->name = kstrndup(name, len, GFP_KERNEL);
>
> shouldn't the string end with '\0'?
>

I agree, it should end with '\0', but fortunately the 'kstrndup()'
function already adds it for us, see mm/util.c, line 100:
(...)
memcpy(buf, s, len);
buf[len] = '\0';
(...)

Kind regards
Rolf