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Revision c3483384ee511ee2af40b4076366cd82a6a47b86 authored by Alexander Duyck on 29 March 2016, 21:55:22 UTC, committed by David S. Miller on 30 March 2016, 20:02:33 UTC 
gro: Allow tunnel stacking in the case of FOU/GUE
 
This patch should fix the issues seen with a recent fix to prevent
tunnel-in-tunnel frames from being generated with GRO.  The fix itself is
correct for now as long as we do not add any devices that support
NETIF_F_GSO_GRE_CSUM.  When such a device is added it could have the
potential to mess things up due to the fact that the outer transport header
points to the outer UDP header and not the GRE header as would be expected.

Fixes: fac8e0f579695 ("tunnels: Don't apply GRO to multiple layers of encapsulation.")
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent fea2485
Raw File
cordic.c 
/*
 * Copyright (c) 2011 Broadcom Corporation
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include <linux/module.h>
#include <linux/cordic.h>

#define CORDIC_ANGLE_GEN	39797
#define CORDIC_PRECISION_SHIFT	16
#define	CORDIC_NUM_ITER		(CORDIC_PRECISION_SHIFT + 2)

#define	FIXED(X)	((s32)((X) << CORDIC_PRECISION_SHIFT))
#define	FLOAT(X)	(((X) >= 0) \
		? ((((X) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1) \
		: -((((-(X)) >> (CORDIC_PRECISION_SHIFT - 1)) + 1) >> 1))

static const s32 arctan_table[] = {
	2949120,
	1740967,
	919879,
	466945,
	234379,
	117304,
	58666,
	29335,
	14668,
	7334,
	3667,
	1833,
	917,
	458,
	229,
	115,
	57,
	29
};

/*
 * cordic_calc_iq() - calculates the i/q coordinate for given angle
 *
 * theta: angle in degrees for which i/q coordinate is to be calculated
 * coord: function output parameter holding the i/q coordinate
 */
struct cordic_iq cordic_calc_iq(s32 theta)
{
	struct cordic_iq coord;
	s32 angle, valtmp;
	unsigned iter;
	int signx = 1;
	int signtheta;

	coord.i = CORDIC_ANGLE_GEN;
	coord.q = 0;
	angle = 0;

	theta = FIXED(theta);
	signtheta = (theta < 0) ? -1 : 1;
	theta = ((theta + FIXED(180) * signtheta) % FIXED(360)) -
		FIXED(180) * signtheta;

	if (FLOAT(theta) > 90) {
		theta -= FIXED(180);
		signx = -1;
	} else if (FLOAT(theta) < -90) {
		theta += FIXED(180);
		signx = -1;
	}

	for (iter = 0; iter < CORDIC_NUM_ITER; iter++) {
		if (theta > angle) {
			valtmp = coord.i - (coord.q >> iter);
			coord.q += (coord.i >> iter);
			angle += arctan_table[iter];
		} else {
			valtmp = coord.i + (coord.q >> iter);
			coord.q -= (coord.i >> iter);
			angle -= arctan_table[iter];
		}
		coord.i = valtmp;
	}

	coord.i *= signx;
	coord.q *= signx;
	return coord;
}
EXPORT_SYMBOL(cordic_calc_iq);

MODULE_DESCRIPTION("CORDIC algorithm");
MODULE_AUTHOR("Broadcom Corporation");
MODULE_LICENSE("Dual BSD/GPL");
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