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Date: Mon, 21 Jan 2008 22:24:17 -0800 From: David Brownell <david-b@...bell.net> To: Dave Young <hidave.darkstar@...il.com> Cc: Greg KH <gregkh@...e.de>, stefanr@...6.in-berlin.de, James.Bottomley@...senpartnership.com, a.zummo@...ertech.it, peterz@...radead.org, cbou@...l.ru, linux-kernel@...r.kernel.org, stern@...land.harvard.edu, dwmw2@...radead.org, davem@...emloft.net, jarkao2@...il.com Subject: Re: [PATCH 1/6] driver-core : add class iteration api 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. > + put_device(dev); > + } else > + error = -ENODEV; > + if (error) > + break; > + } > + up(&class->sem); > + > + return error; > +} > +EXPORT_SYMBOL_GPL(class_for_each_device); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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