Messages in this thread | | | Date | Tue, 22 Jan 2008 14:30:27 +0800 | From | "Dave Young" <> | Subject | Re: [PATCH 1/6] driver-core : add class iteration api |
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On Jan 22, 2008 2:24 PM, David Brownell <david-b@pacbell.net> wrote: > On Monday 21 January 2008, Dave Young wrote: > > > > +/** > > + * class_for_each_device - device iterator > > + * @class: the class we're iterating > > + * @data: data for the callback > > + * @fn: function to be called for each device > > + * > > + * Iterate over @class's list of devices, and call @fn for each, > > + * passing it @data. > > + * > > + * We check the return of @fn each time. If it returns anything > > + * other than 0, we break out and return that value. > > I have a suggestion for better documentation, which > applies to all these utilities: > > > > + */ > > +int class_for_each_device(struct class *class, void *data, > > + int (*fn)(struct device *, void *)) > > +{ > > + struct device *dev; > > + int error = 0; > > + > > + if (!class) > > + return -EINVAL; > > + down(&class->sem); > > + list_for_each_entry(dev, &class->devices, node) { > > + dev = get_device(dev); > > + if (dev) { > > + error = fn(dev, data); > > This is called with class->sem held. So fn() has a > constraint to not re-acquire that ... else it'd be > self-deadlocking. I'd like to see docs at least > mention that; calls to add or remove class members > would be verboten, for example, which isn't an issue > with most other driver model iterators.
Very good comment, thanks david. I will update after a while.
> > > > > + put_device(dev); > > + } else > > + error = -ENODEV; > > + if (error) > > + break; > > + } > > + up(&class->sem); > > + > > + return error; > > +} > > +EXPORT_SYMBOL_GPL(class_for_each_device); >
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