Messages in this thread | | | Date | Thu, 5 Sep 2019 11:02:49 +0200 | From | Greg KH <> | Subject | Re: [PATCH RFC] driver core: ensure a device has valid node id in device_add() |
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On Thu, Sep 05, 2019 at 04:57:00PM +0800, Yunsheng Lin wrote: > On 2019/9/5 15:33, Greg KH wrote: > > On Thu, Sep 05, 2019 at 02:48:24PM +0800, Yunsheng Lin wrote: > >> On 2019/9/5 13:57, Greg KH wrote: > >>> On Thu, Sep 05, 2019 at 09:33:50AM +0800, Yunsheng Lin wrote: > >>>> Currently a device does not belong to any of the numa nodes > >>>> (dev->numa_node is NUMA_NO_NODE) when the FW does not provide > >>>> the node id and the device has not no parent device. > >>>> > >>>> According to discussion in [1]: > >>>> Even if a device's numa node is not set by fw, the device > >>>> really does belong to a node. > >>>> > >>>> This patch sets the device node to node 0 in device_add() if > >>>> the fw has not specified the node id and it either has no > >>>> parent device, or the parent device also does not have a valid > >>>> node id. > >>>> > >>>> There may be explicit handling out there relying on NUMA_NO_NODE, > >>>> like in nvme_probe(). > >>>> > >>>> [1] https://lkml.org/lkml/2019/9/2/466 > >>>> > >>>> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> > >>>> --- > >>>> drivers/base/core.c | 17 ++++++++++++++--- > >>>> include/linux/numa.h | 2 ++ > >>>> 2 files changed, 16 insertions(+), 3 deletions(-) > >>>> > >>>> diff --git a/drivers/base/core.c b/drivers/base/core.c > >>>> index 1669d41..466b8ff 100644 > >>>> --- a/drivers/base/core.c > >>>> +++ b/drivers/base/core.c > >>>> @@ -2107,9 +2107,20 @@ int device_add(struct device *dev) > >>>> if (kobj) > >>>> dev->kobj.parent = kobj; > >>>> > >>>> - /* use parent numa_node */ > >>>> - if (parent && (dev_to_node(dev) == NUMA_NO_NODE)) > >>>> - set_dev_node(dev, dev_to_node(parent)); > >>>> + /* use parent numa_node or default node 0 */ > >>>> + if (!numa_node_valid(dev_to_node(dev))) { > >>>> + int nid = parent ? dev_to_node(parent) : NUMA_NO_NODE; > >>> > >>> Can you expand this to be a "real" if statement please? > >> > >> Sure. May I ask why "? :" is not appropriate here? > > > > Because it is a pain to read, just spell it out and make it obvious what > > is happening. You write code for developers first, and the compiler > > second, and in this case, either way is identical to the compiler. > > > >>>> + > >>>> + if (numa_node_valid(nid)) { > >>>> + set_dev_node(dev, nid); > >>>> + } else { > >>>> + if (nr_node_ids > 1U) > >>>> + pr_err("device: '%s': has invalid NUMA node(%d)\n", > >>>> + dev_name(dev), dev_to_node(dev)); > >>> > >>> dev_err() will show you the exact device properly, instead of having to > >>> rely on dev_name(). > >>> > >>> And what is a user to do if this message happens? How do they fix this? > >>> If they can not, what good is this error message? > >> > >> If user know about their system's topology well enough and node 0 > >> is not the nearest node to the device, maybe user can readjust that by > >> writing the nearest node to /sys/class/pci_bus/XXXX/device/numa_node, > >> if not, then maybe user need to contact the vendor for info or updates. > >> > >> Maybe print error message as below: > >> > >> dev_err(dev, FW_BUG "has invalid NUMA node(%d). Readjust it by writing to sysfs numa_node or contact your vendor for updates.\n", > >> dev_to_node(dev)); > > > > FW_BUG? > > The sysfs numa_node writing interface does print FW_BUG error. > Maybe it is a way of telling the user to contact the vendors, which > pushing the vendors to update the FW.
But is this always going to be caused by a firmware bug? If so, ok, if not, and it's a driver/bus kernel issue, we should not say this.
thanks,
greg k-h
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