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SubjectRe: [PATCH 4/5] mm: add numa node symlink for cpu devices in sysfs
* David Rientjes <rientjes@google.com>:
> On Mon, 19 Oct 2009, Alex Chiang wrote:
>
> > You can discover which CPUs belong to a NUMA node by examining
> > /sys/devices/system/node/$node/
> >
>
> You mean /sys/devices/system/node/node# ?

Hm, in PCI land, I've been using $foo to indicate a variable in
documentation I've written, but I can certainly use foo# if
that's the preferred style.

> > However, it's not convenient to go in the other direction, when looking at
> > /sys/devices/system/cpu/$cpu/
> >
>
> .../cpu/cpu# ?
>
> > Yes, you can muck about in sysfs, but adding these symlinks makes
> > life a lot more convenient.
> >
> > Signed-off-by: Alex Chiang <achiang@hp.com>
> > ---
> >
> > drivers/base/node.c | 9 ++++++++-
> > 1 files changed, 8 insertions(+), 1 deletions(-)
> >
> > diff --git a/drivers/base/node.c b/drivers/base/node.c
> > index ffda067..47a4997 100644
> > --- a/drivers/base/node.c
> > +++ b/drivers/base/node.c
> > @@ -227,6 +227,7 @@ struct node node_devices[MAX_NUMNODES];
> > */
> > int register_cpu_under_node(unsigned int cpu, unsigned int nid)
> > {
> > + int ret;
> > struct sys_device *obj;
> >
> > if (!node_online(nid))
> > @@ -236,9 +237,13 @@ int register_cpu_under_node(unsigned int cpu, unsigned int nid)
> > if (!obj)
> > return 0;
> >
> > - return sysfs_create_link(&node_devices[nid].sysdev.kobj,
> > + ret = sysfs_create_link(&node_devices[nid].sysdev.kobj,
> > &obj->kobj,
> > kobject_name(&obj->kobj));
> > +
> > + return sysfs_create_link(&obj->kobj,
> > + &node_devices[nid].sysdev.kobj,
> > + kobject_name(&node_devices[nid].sysdev.kobj));
> > }
> >
> > int unregister_cpu_under_node(unsigned int cpu, unsigned int nid)
>
> That can't be right, you're ignoring the return value of the first
> sysfs_create_link().

This was a simple oversight. my intent was to return early if the
first call to sysfs_create_link() failed.

> The return values of register_cpu_under_node() and
> unregister_cpu_under_node() are always ignored, so it would probably be
> best to convert these to be void functions. That doesn't mean you can
> simply ignore the result of the first sysfs_create_link(), though: the
> second should probably be suppressed if the first returns an error.
>

I didn't want to change too much in the patch. Changing the
function signature seems a bit overeager, but if you have strong
feelings, I can do so.

Thanks for the review.

/ac



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