Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422691AbWJFNfM (ORCPT ); Fri, 6 Oct 2006 09:35:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422689AbWJFNfL (ORCPT ); Fri, 6 Oct 2006 09:35:11 -0400 Received: from mx1.redhat.com ([66.187.233.31]:38306 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1422703AbWJFNfE (ORCPT ); Fri, 6 Oct 2006 09:35:04 -0400 From: David Howells Subject: [PATCH 1/4] LOG2: Implement a general integer log2 facility in the kernel [try #4] Date: Fri, 06 Oct 2006 14:34:14 +0100 To: torvalds@osdl.org, akpm@osdl.org, sfr@canb.auug.org.au Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, dhowells@redhat.com Message-Id: <20061006133414.9972.79007.stgit@warthog.cambridge.redhat.com> Content-Type: text/plain; charset=utf-8; format=fixed Content-Transfer-Encoding: 8bit User-Agent: StGIT/0.10 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 23028 Lines: 905 From: David Howells This facility provides three entry points: ilog2() Log base 2 of unsigned long ilog2_u32() Log base 2 of u32 ilog2_u64() Log base 2 of u64 These facilities can either be used inside functions on dynamic data: int do_something(long q) { ...; y = ilog2(x) ...; } Or can be used to statically initialise global variables with constant values: unsigned n = ilog2(27); When performing static initialisation, the compiler will report "error: initializer element is not constant" if asked to take a log of zero or of something not reducible to a constant. They treat negative numbers as unsigned. When not dealing with a constant, they fall back to using fls() which permits them to use arch-specific log calculation instructions - such as BSR on x86/x86_64 or SCAN on FRV - if available. Signed-Off-By: David Howells --- arch/alpha/Kconfig | 8 ++ arch/arm/Kconfig | 8 ++ arch/arm26/Kconfig | 8 ++ arch/avr32/Kconfig | 8 ++ arch/cris/Kconfig | 8 ++ arch/frv/Kconfig | 8 ++ arch/h8300/Kconfig | 8 ++ arch/i386/Kconfig.cpu | 8 ++ arch/ia64/Kconfig | 8 ++ arch/m32r/Kconfig | 8 ++ arch/m68k/Kconfig | 8 ++ arch/m68knommu/Kconfig | 8 ++ arch/mips/Kconfig | 8 ++ arch/parisc/Kconfig | 8 ++ arch/powerpc/Kconfig | 8 ++ arch/ppc/Kconfig | 8 ++ arch/s390/Kconfig | 8 ++ arch/sh/Kconfig | 8 ++ arch/sh64/Kconfig | 8 ++ arch/sparc/Kconfig | 8 ++ arch/sparc64/Kconfig | 8 ++ arch/v850/Kconfig | 8 ++ arch/x86_64/Kconfig | 8 ++ arch/xtensa/Kconfig | 8 ++ drivers/infiniband/hw/mthca/mthca_provider.c | 4 - drivers/infiniband/hw/mthca/mthca_qp.c | 4 - drivers/infiniband/hw/mthca/mthca_srq.c | 4 - drivers/infiniband/ulp/iser/iser_memory.c | 4 - fs/ext2/super.c | 6 - fs/ext3/super.c | 6 - include/asm-frv/bitops.h | 44 +++++++++ include/linux/kernel.h | 9 -- include/linux/log2.h | 131 ++++++++++++++++++++++++++ mm/page_alloc.c | 4 - 34 files changed, 382 insertions(+), 26 deletions(-) diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 7e55ea6..84caf50 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -25,6 +25,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index adb05de..0c3dab6 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -74,6 +74,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/arm26/Kconfig b/arch/arm26/Kconfig index c14fe91..74eba8b 100644 --- a/arch/arm26/Kconfig +++ b/arch/arm26/Kconfig @@ -41,6 +41,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig index 5f1694e..bb059a4 100644 --- a/arch/avr32/Kconfig +++ b/arch/avr32/Kconfig @@ -45,6 +45,14 @@ config GENERIC_TIME config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_BUST_SPINLOCK bool diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig index 6a1238a..3474309 100644 --- a/arch/cris/Kconfig +++ b/arch/cris/Kconfig @@ -16,6 +16,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig index cf1c446..7561d7b 100644 --- a/arch/frv/Kconfig +++ b/arch/frv/Kconfig @@ -41,6 +41,14 @@ config TIME_LOW_RES bool default y +config ARCH_HAS_ILOG2_U32 + bool + default y + +config ARCH_HAS_ILOG2_U64 + bool + default y + mainmenu "Fujitsu FR-V Kernel Configuration" source "init/Kconfig" diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig index cabf0bf..34a84bc 100644 --- a/arch/h8300/Kconfig +++ b/arch/h8300/Kconfig @@ -29,6 +29,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default n +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/i386/Kconfig.cpu b/arch/i386/Kconfig.cpu index 21c9a4e..99fa842 100644 --- a/arch/i386/Kconfig.cpu +++ b/arch/i386/Kconfig.cpu @@ -240,6 +240,14 @@ config RWSEM_XCHGADD_ALGORITHM depends on !M386 default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_CALIBRATE_DELAY bool default y diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index 70f7eb9..ac23182 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -34,6 +34,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig index 41fd490..f383dab 100644 --- a/arch/m32r/Kconfig +++ b/arch/m32r/Kconfig @@ -214,6 +214,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default n +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig index 805b81f..0953145 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -17,6 +17,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/m68knommu/Kconfig b/arch/m68knommu/Kconfig index 6d920d4..0e07597 100644 --- a/arch/m68knommu/Kconfig +++ b/arch/m68knommu/Kconfig @@ -25,6 +25,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default n +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 8a49884..8f10fe2 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -789,6 +789,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index d210123..0f9ff61 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -25,6 +25,14 @@ config RWSEM_GENERIC_SPINLOCK config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_FIND_NEXT_BIT bool default y diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 8b69104..1cf67b7 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -41,6 +41,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/ppc/Kconfig b/arch/ppc/Kconfig index 077711e..55abcc9 100644 --- a/arch/ppc/Kconfig +++ b/arch/ppc/Kconfig @@ -19,6 +19,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 51c2dfe..a3f9550 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -22,6 +22,14 @@ config RWSEM_XCHGADD_ALGORITHM bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_HWEIGHT bool default y diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig index f6a0c44..eaea396 100644 --- a/arch/sh/Kconfig +++ b/arch/sh/Kconfig @@ -48,6 +48,14 @@ config GENERIC_IOMAP config ARCH_MAY_HAVE_PC_FDC bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source "init/Kconfig" menu "System type" diff --git a/arch/sh64/Kconfig b/arch/sh64/Kconfig index 58c678e..03778a1 100644 --- a/arch/sh64/Kconfig +++ b/arch/sh64/Kconfig @@ -36,6 +36,14 @@ config GENERIC_CALIBRATE_DELAY config RWSEM_XCHGADD_ALGORITHM bool +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config GENERIC_ISA_DMA bool diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index 9431e96..44b79c2 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -166,6 +166,14 @@ config ARCH_MAY_HAVE_PC_FDC bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config SUN_PM bool default y diff --git a/arch/sparc64/Kconfig b/arch/sparc64/Kconfig index b627f8d..d391d11 100644 --- a/arch/sparc64/Kconfig +++ b/arch/sparc64/Kconfig @@ -34,6 +34,14 @@ config ARCH_MAY_HAVE_PC_FDC bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + config AUDIT_ARCH bool default y diff --git a/arch/v850/Kconfig b/arch/v850/Kconfig index 37ec644..bcf8258 100644 --- a/arch/v850/Kconfig +++ b/arch/v850/Kconfig @@ -38,6 +38,14 @@ config TIME_LOW_RES bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + # Turn off some random 386 crap that can affect device config config ISA bool diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig index 010d226..c007ab2 100644 --- a/arch/x86_64/Kconfig +++ b/arch/x86_64/Kconfig @@ -96,6 +96,14 @@ config AUDIT_ARCH bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source "init/Kconfig" diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index c1e69a1..9eccfbd 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -34,6 +34,14 @@ config GENERIC_HARDIRQS bool default y +config ARCH_HAS_ILOG2_U32 + bool + default n + +config ARCH_HAS_ILOG2_U64 + bool + default n + source "init/Kconfig" menu "Processor type and features" diff --git a/drivers/infiniband/hw/mthca/mthca_provider.c b/drivers/infiniband/hw/mthca/mthca_provider.c index 981fe2e..20c0fc1 100644 --- a/drivers/infiniband/hw/mthca/mthca_provider.c +++ b/drivers/infiniband/hw/mthca/mthca_provider.c @@ -124,7 +124,7 @@ static int mthca_query_device(struct ib_ props->max_map_per_fmr = 255; else props->max_map_per_fmr = - (1 << (32 - long_log2(mdev->limits.num_mpts))) - 1; + (1 << (32 - ilog2(mdev->limits.num_mpts))) - 1; err = 0; out: @@ -814,7 +814,7 @@ static int mthca_resize_cq(struct ib_cq lkey = ucmd.lkey; } - ret = mthca_RESIZE_CQ(dev, cq->cqn, lkey, long_log2(entries), &status); + ret = mthca_RESIZE_CQ(dev, cq->cqn, lkey, ilog2(entries), &status); if (status) ret = -EINVAL; diff --git a/drivers/infiniband/hw/mthca/mthca_qp.c b/drivers/infiniband/hw/mthca/mthca_qp.c index 5e5c58b..1bf0856 100644 --- a/drivers/infiniband/hw/mthca/mthca_qp.c +++ b/drivers/infiniband/hw/mthca/mthca_qp.c @@ -635,11 +635,11 @@ int mthca_modify_qp(struct ib_qp *ibqp, if (mthca_is_memfree(dev)) { if (qp->rq.max) - qp_context->rq_size_stride = long_log2(qp->rq.max) << 3; + qp_context->rq_size_stride = ilog2(qp->rq.max) << 3; qp_context->rq_size_stride |= qp->rq.wqe_shift - 4; if (qp->sq.max) - qp_context->sq_size_stride = long_log2(qp->sq.max) << 3; + qp_context->sq_size_stride = ilog2(qp->sq.max) << 3; qp_context->sq_size_stride |= qp->sq.wqe_shift - 4; } diff --git a/drivers/infiniband/hw/mthca/mthca_srq.c b/drivers/infiniband/hw/mthca/mthca_srq.c index 0f316c8..2af1b8e 100644 --- a/drivers/infiniband/hw/mthca/mthca_srq.c +++ b/drivers/infiniband/hw/mthca/mthca_srq.c @@ -118,7 +118,7 @@ static void mthca_arbel_init_srq_context memset(context, 0, sizeof *context); - logsize = long_log2(srq->max) + srq->wqe_shift; + logsize = ilog2(srq->max) + srq->wqe_shift; context->state_logsize_srqn = cpu_to_be32(logsize << 24 | srq->srqn); context->lkey = cpu_to_be32(srq->mr.ibmr.lkey); context->db_index = cpu_to_be32(srq->db_index); @@ -209,7 +209,7 @@ int mthca_alloc_srq(struct mthca_dev *de if (!mthca_is_memfree(dev) && (ds > dev->limits.max_desc_sz)) return -EINVAL; - srq->wqe_shift = long_log2(ds); + srq->wqe_shift = ilog2(ds); srq->srqn = mthca_alloc(&dev->srq_table.alloc); if (srq->srqn == -1) diff --git a/drivers/infiniband/ulp/iser/iser_memory.c b/drivers/infiniband/ulp/iser/iser_memory.c index 0606744..15de90e 100644 --- a/drivers/infiniband/ulp/iser/iser_memory.c +++ b/drivers/infiniband/ulp/iser/iser_memory.c @@ -113,7 +113,7 @@ int iser_start_rdma_unaligned_sg(struct if (cmd_data_len > ISER_KMALLOC_THRESHOLD) mem = (void *)__get_free_pages(GFP_NOIO, - long_log2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT); + ilog2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT); else mem = kmalloc(cmd_data_len, GFP_NOIO); @@ -210,7 +210,7 @@ void iser_finalize_rdma_unaligned_sg(str if (cmd_data_len > ISER_KMALLOC_THRESHOLD) free_pages((unsigned long)mem_copy->copy_buf, - long_log2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT); + ilog2(roundup_pow_of_two(cmd_data_len)) - PAGE_SHIFT); else kfree(mem_copy->copy_buf); diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 513cd42..4f0bd87 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -593,8 +593,6 @@ static int ext2_check_descriptors (struc return 1; } -#define log2(n) ffz(~(n)) - /* * Maximal file size. There is a direct, and {,double-,triple-}indirect * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks. @@ -828,9 +826,9 @@ static int ext2_fill_super(struct super_ sbi->s_sbh = bh; sbi->s_mount_state = le16_to_cpu(es->s_state); sbi->s_addr_per_block_bits = - log2 (EXT2_ADDR_PER_BLOCK(sb)); + ilog2 (EXT2_ADDR_PER_BLOCK(sb)); sbi->s_desc_per_block_bits = - log2 (EXT2_DESC_PER_BLOCK(sb)); + ilog2 (EXT2_DESC_PER_BLOCK(sb)); if (sb->s_magic != EXT2_SUPER_MAGIC) goto cantfind_ext2; diff --git a/fs/ext3/super.c b/fs/ext3/super.c index 8bfd56e..b97119c 100644 --- a/fs/ext3/super.c +++ b/fs/ext3/super.c @@ -1341,8 +1341,6 @@ #endif sb->s_flags = s_flags; /* Restore MS_RDONLY status */ } -#define log2(n) ffz(~(n)) - /* * Maximal file size. There is a direct, and {,double-,triple-}indirect * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks. @@ -1589,8 +1587,8 @@ static int ext3_fill_super (struct super sbi->s_desc_per_block = blocksize / sizeof(struct ext3_group_desc); sbi->s_sbh = bh; sbi->s_mount_state = le16_to_cpu(es->s_state); - sbi->s_addr_per_block_bits = log2(EXT3_ADDR_PER_BLOCK(sb)); - sbi->s_desc_per_block_bits = log2(EXT3_DESC_PER_BLOCK(sb)); + sbi->s_addr_per_block_bits = ilog2(EXT3_ADDR_PER_BLOCK(sb)); + sbi->s_desc_per_block_bits = ilog2(EXT3_DESC_PER_BLOCK(sb)); for (i=0; i < 4; i++) sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]); sbi->s_def_hash_version = es->s_def_hash_version; diff --git a/include/asm-frv/bitops.h b/include/asm-frv/bitops.h index 1f70d47..f8560ed 100644 --- a/include/asm-frv/bitops.h +++ b/include/asm-frv/bitops.h @@ -256,6 +256,50 @@ int __ffs(unsigned long x) return 31 - bit; } +/* + * special slimline version of fls() for calculating ilog2_u32() + * - note: no protection against n == 0 + */ +#define ARCH_HAS_ILOG2_U32 +static inline __attribute__((const)) +int __ilog2_u32(u32 n) +{ + int bit; + asm("scan %1,gr0,%0" : "=r"(bit) : "r"(n)); + return 31 - bit; +} + +/* + * special slimline version of fls64() for calculating ilog2_u64() + * - note: no protection against n == 0 + */ +#define ARCH_HAS_ILOG2_U64 +static inline __attribute__((const)) +int __ilog2_u64(u64 n) +{ + union { + u64 ll; + struct { u32 h, l; }; + } _; + int bit, x, y; + + _.ll = n; + + asm(" subcc %3,gr0,gr0,icc0 \n" + " ckeq icc0,cc4 \n" + " cscan.p %3,gr0,%0 ,cc4,0 \n" + " setlos #63,%1 \n" + " cscan.p %4,gr0,%0 ,cc4,1 \n" + " setlos #31,%2 \n" + " csub.p %1,%0,%0 ,cc4,0 \n" + " csub %2,%0,%0 ,cc4,1 \n" + : "=&r"(bit), "=r"(x), "=r"(y) + : "0r"(_.h), "r"(_.l) + : "icc0", "cc4" + ); + return bit; +} + #include #include diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 80f39ca..473101a 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -13,6 +13,7 @@ #include #include #include #include +#include #include #include @@ -155,14 +156,6 @@ #endif unsigned long int_sqrt(unsigned long); -static inline int __attribute_pure__ long_log2(unsigned long x) -{ - int r = 0; - for (x >>= 1; x > 0; x >>= 1) - r++; - return r; -} - static inline unsigned long __attribute_const__ roundup_pow_of_two(unsigned long x) { diff --git a/include/linux/log2.h b/include/linux/log2.h new file mode 100644 index 0000000..3979c60 --- /dev/null +++ b/include/linux/log2.h @@ -0,0 +1,131 @@ +/* Integer base 2 logarithm calculation + * + * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#ifndef _LINUX_LOG2_H +#define _LINUX_LOG2_H + +#include +#include + +/* + * deal with unrepresentable constant logarithms + */ +extern __attribute__((const, noreturn)) +int ____ilog2_NaN(void); + +/* + * non-constant log of base 2 calculators + * - the arch may override these in asm/bitops.h if they can be implemented + * more efficiently than using fls() and fls64() + * - the arch is not required to handle n==0 if implementing the fallback + */ +#ifndef CONFIG_ARCH_HAS_ILOG2_U32 +static inline __attribute__((const)) +int __ilog2_u32(u32 n) +{ + return fls(n) - 1; +} +#endif + +#ifndef CONFIG_ARCH_HAS_ILOG2_U64 +static inline __attribute__((const)) +int __ilog2_u64(u64 n) +{ + return fls64(n) - 1; +} +#endif + +/** + * ilog2 - log of base 2 of 32-bit or a 64-bit unsigned value + * @n - parameter + * + * constant-capable log of base 2 calculation + * - this can be used to initialise global variables from constant data, hence + * the massive ternary operator construction + * + * selects the appropriately-sized optimised version depending on sizeof(n) + */ +#define ilog2(n) \ +( \ + __builtin_constant_p(n) ? ( \ + (n) < 1 ? ____ilog2_NaN() : \ + (n) & (1ULL << 63) ? 63 : \ + (n) & (1ULL << 62) ? 62 : \ + (n) & (1ULL << 61) ? 61 : \ + (n) & (1ULL << 60) ? 60 : \ + (n) & (1ULL << 59) ? 59 : \ + (n) & (1ULL << 58) ? 58 : \ + (n) & (1ULL << 57) ? 57 : \ + (n) & (1ULL << 56) ? 56 : \ + (n) & (1ULL << 55) ? 55 : \ + (n) & (1ULL << 54) ? 54 : \ + (n) & (1ULL << 53) ? 53 : \ + (n) & (1ULL << 52) ? 52 : \ + (n) & (1ULL << 51) ? 51 : \ + (n) & (1ULL << 50) ? 50 : \ + (n) & (1ULL << 49) ? 49 : \ + (n) & (1ULL << 48) ? 48 : \ + (n) & (1ULL << 47) ? 47 : \ + (n) & (1ULL << 46) ? 46 : \ + (n) & (1ULL << 45) ? 45 : \ + (n) & (1ULL << 44) ? 44 : \ + (n) & (1ULL << 43) ? 43 : \ + (n) & (1ULL << 42) ? 42 : \ + (n) & (1ULL << 41) ? 41 : \ + (n) & (1ULL << 40) ? 40 : \ + (n) & (1ULL << 39) ? 39 : \ + (n) & (1ULL << 38) ? 38 : \ + (n) & (1ULL << 37) ? 37 : \ + (n) & (1ULL << 36) ? 36 : \ + (n) & (1ULL << 35) ? 35 : \ + (n) & (1ULL << 34) ? 34 : \ + (n) & (1ULL << 33) ? 33 : \ + (n) & (1ULL << 32) ? 32 : \ + (n) & (1ULL << 31) ? 31 : \ + (n) & (1ULL << 30) ? 30 : \ + (n) & (1ULL << 29) ? 29 : \ + (n) & (1ULL << 28) ? 28 : \ + (n) & (1ULL << 27) ? 27 : \ + (n) & (1ULL << 26) ? 26 : \ + (n) & (1ULL << 25) ? 25 : \ + (n) & (1ULL << 24) ? 24 : \ + (n) & (1ULL << 23) ? 23 : \ + (n) & (1ULL << 22) ? 22 : \ + (n) & (1ULL << 21) ? 21 : \ + (n) & (1ULL << 20) ? 20 : \ + (n) & (1ULL << 19) ? 19 : \ + (n) & (1ULL << 18) ? 18 : \ + (n) & (1ULL << 17) ? 17 : \ + (n) & (1ULL << 16) ? 16 : \ + (n) & (1ULL << 15) ? 15 : \ + (n) & (1ULL << 14) ? 14 : \ + (n) & (1ULL << 13) ? 13 : \ + (n) & (1ULL << 12) ? 12 : \ + (n) & (1ULL << 11) ? 11 : \ + (n) & (1ULL << 10) ? 10 : \ + (n) & (1ULL << 9) ? 9 : \ + (n) & (1ULL << 8) ? 8 : \ + (n) & (1ULL << 7) ? 7 : \ + (n) & (1ULL << 6) ? 6 : \ + (n) & (1ULL << 5) ? 5 : \ + (n) & (1ULL << 4) ? 4 : \ + (n) & (1ULL << 3) ? 3 : \ + (n) & (1ULL << 2) ? 2 : \ + (n) & (1ULL << 1) ? 1 : \ + (n) & (1ULL << 0) ? 0 : \ + ____ilog2_NaN() \ + ) : \ + (sizeof(n) <= 4) ? \ + __ilog2_u32(n) : \ + __ilog2_u64(n) \ + ) + +#endif /* _LINUX_LOG2_H */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index a8c003e..bd30dff 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3091,7 +3091,7 @@ void *__init alloc_large_system_hash(con if (numentries > max) numentries = max; - log2qty = long_log2(numentries); + log2qty = ilog2(numentries); do { size = bucketsize << log2qty; @@ -3113,7 +3113,7 @@ void *__init alloc_large_system_hash(con printk("%s hash table entries: %d (order: %d, %lu bytes)\n", tablename, (1U << log2qty), - long_log2(size) - PAGE_SHIFT, + ilog2(size) - PAGE_SHIFT, size); if (_hash_shift) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/