Re: [RFC PATCH 2/3] USB: kill urb->use_count atomic variable

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On Mon, Aug 19, 2013 at 07:04:19PM +0800, Ming Lei wrote:
> This patch kills atomic_inc/atomic_dec operations on
> urb->use_count in URB submit/complete path.

Any reason only this patch was "RFC"?

And you didn't kill them all, please look closer, this should have no
affect on "speed", did you measure it?

> The urb->use_count is only used for unlinking URB, and it isn't
> necessary defined as atomic counter, so the variable is renamed
> as urb->use_flag for this purpose, then reading/writing the
> flag is still kept as atomic but ARCH's atomic operations(atomic_inc/
> atomic_dec) are saved.

That sentence made no sense to me at all :(

And how is atomic_set() any faster/slower than atomic_inc/dec?  The same
memory barriers kick in, right?

confused,

greg k-h
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