On Sunday 21 January 2007 6:25 pm, Atsushi Nemoto wrote:
> Here is a revised version. The children list of spi_master_class
> contains only spi_master class so we can just compare bus_num member
> instead of class_id string.
Looks just a bit iffy ... though, thanks for helping to finally
sort this out!
> + down(&spi_master_class.sem);
> + list_for_each_entry(cdev, &spi_master_class.children, node) {
> + cdev = class_device_get(cdev);
> + if (!cdev)
> + continue;
That "continue" case doesn't seem like it should be possible... but
at any rate, the "get" can be deferred until the relevent class
device is known, since that _valid_ handle can't disappear so long
as that semaphore is held. And if you find the right device but
can't get a reference ... no point in continuing!
Something like a class_find_device() would be the best way to solve
this sort of problem, IMO. But we don't have one of those. :(
> + master = container_of(cdev, struct spi_master, cdev);
> + if (master->bus_num == bus_num)
> + break;
> + master = NULL;
> + class_device_put(cdev);
> + }
> + up(&spi_master_class.sem);
> + return master;
> }
> EXPORT_SYMBOL_GPL(spi_busnum_to_master);
>
>
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