Re: [RFC PATCH] Input: evdev - drop redundant list-locking

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Hi

On Sun, Jul 20, 2014 at 8:54 PM, Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx> wrote:
> On Sun, Jul 20, 2014 at 08:48:12PM +0200, David Herrmann wrote:
>> evdev->client_list is rcu-protected. There is no need to have a
>> separate spinlock just for the list. Either one is good enough, so lets
>> drop the spinlock.
>>
>> Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx>
>> ---
>> Hi
>>
>> I stumbled across this one when doing some evdev reviews. Maybe I'm missing
>> something obvious and I should stop coding on Sundays. But the RCU-protection
>> should be enough here, right?
>
> RCU protection is for traversing list only, writes (as is adding and removing
> elements from client_list) still have to be mutually exclusive.

Oh, you mean to protect against concurrent writes? Right, but we could
just use evdev->mutex for that. I mean all paths that call
attach_client() or detach_client() already lock evdev->mutex at some
point. It would allow us to get rid of the lock.

Thanks
David
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