Re: [PATCH v2 01/10] usb: host: ehci-sched: refactor scan_isoc function

From: Alan Stern
Date: Sun Dec 13 2015 - 10:29:22 EST


On Sun, 13 Dec 2015, Geyslan G. Bem wrote:

> This patch removes an infinite 'for' loop and makes use of the already
> existing 'restart' tag instead, reducing one leading tab.
>
> It also puts the easier evaluation (live variable) to be the first in
> two conditionals.
>
> if (live && frame == now_frame) { ...
>
> if (live && ((frame == now_frame) || ...

You should never do this. The first test in a conditional should be
the one that is most likely to cause the expression to fail. In this
case, live is almost always true whereas frame == now_frame is true
only some percentage of the time. Therefore the frame == now_frame
test should come first.

Alan Stern

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