Messages in this thread | | | From | Tri Vo <> | Date | Tue, 30 Jul 2019 12:20:16 -0700 | Subject | Re: [PATCH v5] PM / wakeup: show wakeup sources stats in sysfs |
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On Mon, Jul 29, 2019 at 11:47 PM Greg KH <gregkh@linuxfoundation.org> wrote: > > On Mon, Jul 29, 2019 at 07:43:09PM -0700, Tri Vo wrote: > > Userspace can use wakeup_sources debugfs node to plot history of suspend > > blocking wakeup sources over device's boot cycle. This information can > > then be used (1) for power-specific bug reporting and (2) towards > > attributing battery consumption to specific processes over a period of > > time. > > > > However, debugfs doesn't have stable ABI. For this reason, create a > > 'struct device' to expose wakeup sources statistics in sysfs under > > /sys/class/wakeup/wakeup<ID>/*. > > I agree with Rafael here, no need for the extra "wakeup" in the device > name as you are in the "wakeup" namespace already. > > If you have an IDA-allocated name, there's no need for the extra > 'wakeup' at all. > > > +int wakeup_source_sysfs_add(struct device *parent, struct wakeup_source *ws) > > +{ > > + struct device *dev; > > + int id; > > + > > + id = ida_simple_get(&wakeup_ida, 0, 0, GFP_KERNEL); > > + if (id < 0) > > + return id; > > No lock needed for this ida? Are you sure? > > > + ws->id = id; > > + > > + dev = device_create_with_groups(wakeup_class, parent, MKDEV(0, 0), ws, > > + wakeup_source_groups, "wakeup%d", > > + ws->id); > > + if (IS_ERR(dev)) { > > + ida_simple_remove(&wakeup_ida, ws->id); > > + return PTR_ERR(dev); > > + } > > + > > + ws->dev = dev; > > + return 0; > > +} > > +EXPORT_SYMBOL_GPL(wakeup_source_sysfs_add); > > + > > +/** > > + * wakeup_source_sysfs_remove - Remove wakeup_source attributes from sysfs. > > + * @ws: Wakeup source to be removed from sysfs. > > + */ > > +void wakeup_source_sysfs_remove(struct wakeup_source *ws) > > +{ > > + device_unregister(ws->dev); > > + ida_simple_remove(&wakeup_ida, ws->id); > > Again, no lock, is that ok? I think ida's can work without a lock, but > not always, sorry, I don't remember the rules anymore given the recent > changes in that code.
Documentation says, "The IDA handles its own locking. It is safe to call any of the IDA functions without synchronisation in your code." https://www.kernel.org/doc/html/latest/core-api/idr.html#ida-usage
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