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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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