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The kernel source contains several definitions of an ilog2 function; some are slower than necessary, and one of them is incorrect. Elimininate them all and define an ilog2 macro in libkern to replace them, in a way that is fast, correct for all argument types, and, in a GENERIC kernel, includes a check for an invalid zero parameter. Folks at Microsoft have verified that having a correct ilog2 definition for their MANA driver doesn't break it. Reviewed by: alc, markj, mhorne (older version), jhibbits (older version) Differential Revision: https://reviews.freebsd.org/D45170 Differential Revision: https://reviews.freebsd.org/D45235 (cherry picked from commit b0056b31e90029553894d17c441cbb2c06d31412)
56 lines
1.9 KiB
C
56 lines
1.9 KiB
C
/*-
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* Copyright (c) 2010 Isilon Systems, Inc.
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* Copyright (c) 2010 iX Systems, Inc.
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* Copyright (c) 2010 Panasas, Inc.
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* Copyright (c) 2013-2015 Mellanox Technologies, Ltd.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _LINUXKPI_LINUX_LOG2_H_
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#define _LINUXKPI_LINUX_LOG2_H_
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#include <linux/types.h>
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#include <sys/libkern.h>
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static inline unsigned long
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roundup_pow_of_two(unsigned long x)
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{
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return (1UL << flsl(x - 1));
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}
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static inline int
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is_power_of_2(unsigned long n)
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{
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return (n == roundup_pow_of_two(n));
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}
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static inline unsigned long
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rounddown_pow_of_two(unsigned long x)
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{
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return (1UL << (flsl(x) - 1));
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}
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#define order_base_2(x) ilog2(roundup_pow_of_two(x))
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#endif /* _LINUXKPI_LINUX_LOG2_H_ */
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