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usbip: fix off-by-one frame number calculation

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vgadget_get_frame returns a frame number from 0 to 2046, which
may require an expensive division operation to wrap at one lower
than the usual number.

I can't see any reason for this, and all other drivers wrap at
a power-of-two number. My best explanation is that it was a simple
typo, so I'm changing the % modulo operator into a cheaper bitmask
that the other drivers use, to make it wrap after 0x7ff rather than
before it.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Arnd Bergmann 2017-11-07 11:39:56 +01:00 committed by Greg Kroah-Hartman
parent 12f28144cf
commit 15081e85cc
1 changed files with 1 additions and 1 deletions
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2
drivers/usb/usbip/vudc_dev.c
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@ -145,7 +145,7 @@ static int vgadget_get_frame(struct usb_gadget *_gadget)
do_gettimeofday(&now);
return ((now.tv_sec - udc->start_time.tv_sec) * 1000 +
(now.tv_usec - udc->start_time.tv_usec) / 1000)
% 0x7FF;
& 0x7FF;
}
static int vgadget_set_selfpowered(struct usb_gadget *_gadget, int value)