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Date: Tue, 19 Nov 2019 11:13:21 +0000
From: Andrew Murray <andrew.murray@....com>
To: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Cc: maz@...nel.org, linux-kernel@...r.kernel.org,
Tariq Toukan <tariqt@...lanox.com>,
Tom Joseph <tjoseph@...ence.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Shawn Lin <shawn.lin@...k-chips.com>,
Heiko Stuebner <heiko@...ech.de>,
Christoph Hellwig <hch@....de>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Robin Murphy <robin.murphy@....com>,
james.quinlan@...adcom.com, mbrugger@...e.com,
f.fainelli@...il.com, phil@...pberrypi.org, wahrenst@....net,
jeremy.linton@....com, "David S. Miller" <davem@...emloft.net>,
Bjorn Helgaas <bhelgaas@...gle.com>, netdev@...r.kernel.org,
linux-rdma@...r.kernel.org, linux-pci@...r.kernel.org,
linux-rockchip@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org,
iommu@...ts.linux-foundation.org
Subject: Re: [PATCH v2 1/6] linux/log2.h: Add roundup/rounddown_pow_two64()
family of functions
On Tue, Nov 12, 2019 at 04:59:20PM +0100, Nicolas Saenz Julienne wrote:
> Some users need to make sure their rounding function accepts and returns
> 64bit long variables regardless of the architecture. Sadly
> roundup/rounddown_pow_two() takes and returns unsigned longs. Create a
> new generic 64bit variant of the function and cleanup rougue custom
> implementations.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> ---
> drivers/net/ethernet/mellanox/mlx4/en_clock.c | 3 +-
> drivers/pci/controller/pcie-cadence-ep.c | 7 +--
> drivers/pci/controller/pcie-cadence.c | 7 +--
> drivers/pci/controller/pcie-rockchip-ep.c | 9 ++--
Thanks for making this change. See comments inline...
> include/linux/log2.h | 52 +++++++++++++++++++
> kernel/dma/direct.c | 3 +-
> 6 files changed, 63 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_clock.c b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> index 024788549c25..027bd72505e2 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> @@ -33,6 +33,7 @@
>
> #include <linux/mlx4/device.h>
> #include <linux/clocksource.h>
> +#include <linux/log2.h>
>
> #include "mlx4_en.h"
>
> @@ -252,7 +253,7 @@ static u32 freq_to_shift(u16 freq)
> {
> u32 freq_khz = freq * 1000;
> u64 max_val_cycles = freq_khz * 1000 * MLX4_EN_WRAP_AROUND_SEC;
> - u64 max_val_cycles_rounded = 1ULL << fls64(max_val_cycles - 1);
> + u64 max_val_cycles_rounded = roundup_pow_of_two64(max_val_cycles);
> /* calculate max possible multiplier in order to fit in 64bit */
> u64 max_mul = div64_u64(ULLONG_MAX, max_val_cycles_rounded);
>
> diff --git a/drivers/pci/controller/pcie-cadence-ep.c b/drivers/pci/controller/pcie-cadence-ep.c
> index def7820cb824..26ff424b16f5 100644
> --- a/drivers/pci/controller/pcie-cadence-ep.c
> +++ b/drivers/pci/controller/pcie-cadence-ep.c
> @@ -10,6 +10,7 @@
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> #include <linux/sizes.h>
> +#include <linux/log2.h>
>
> #include "pcie-cadence.h"
>
> @@ -90,11 +91,7 @@ static int cdns_pcie_ep_set_bar(struct pci_epc *epc, u8 fn,
>
> /* BAR size is 2^(aperture + 7) */
> sz = max_t(size_t, epf_bar->size, CDNS_PCIE_EP_MIN_APERTURE);
> - /*
> - * roundup_pow_of_two() returns an unsigned long, which is not suited
> - * for 64bit values.
> - */
> - sz = 1ULL << fls64(sz - 1);
> + sz = roundup_pow_of_two64(sz);
> aperture = ilog2(sz) - 7; /* 128B -> 0, 256B -> 1, 512B -> 2, ... */
>
> if ((flags & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO) {
> diff --git a/drivers/pci/controller/pcie-cadence.c b/drivers/pci/controller/pcie-cadence.c
> index cd795f6fc1e2..b2278e6b955c 100644
> --- a/drivers/pci/controller/pcie-cadence.c
> +++ b/drivers/pci/controller/pcie-cadence.c
> @@ -4,6 +4,7 @@
> // Author: Cyrille Pitchen <cyrille.pitchen@...e-electrons.com>
>
> #include <linux/kernel.h>
> +#include <linux/log2.h>
>
> #include "pcie-cadence.h"
>
> @@ -11,11 +12,7 @@ void cdns_pcie_set_outbound_region(struct cdns_pcie *pcie, u8 fn,
> u32 r, bool is_io,
> u64 cpu_addr, u64 pci_addr, size_t size)
> {
> - /*
> - * roundup_pow_of_two() returns an unsigned long, which is not suited
> - * for 64bit values.
> - */
> - u64 sz = 1ULL << fls64(size - 1);
> + u64 sz = roundup_pow_of_two64(size);
> int nbits = ilog2(sz);
> u32 addr0, addr1, desc0, desc1;
>
> diff --git a/drivers/pci/controller/pcie-rockchip-ep.c b/drivers/pci/controller/pcie-rockchip-ep.c
> index d743b0a48988..ed50aaf27784 100644
> --- a/drivers/pci/controller/pcie-rockchip-ep.c
> +++ b/drivers/pci/controller/pcie-rockchip-ep.c
> @@ -16,6 +16,7 @@
> #include <linux/platform_device.h>
> #include <linux/pci-epf.h>
> #include <linux/sizes.h>
> +#include <linux/log2.h>
>
> #include "pcie-rockchip.h"
>
> @@ -70,7 +71,7 @@ static void rockchip_pcie_prog_ep_ob_atu(struct rockchip_pcie *rockchip, u8 fn,
> u32 r, u32 type, u64 cpu_addr,
> u64 pci_addr, size_t size)
> {
> - u64 sz = 1ULL << fls64(size - 1);
> + u64 sz = roundup_pow_of_two64(size);
> int num_pass_bits = ilog2(sz);
> u32 addr0, addr1, desc0, desc1;
> bool is_nor_msg = (type == AXI_WRAPPER_NOR_MSG);
> @@ -172,11 +173,7 @@ static int rockchip_pcie_ep_set_bar(struct pci_epc *epc, u8 fn,
> /* BAR size is 2^(aperture + 7) */
> sz = max_t(size_t, epf_bar->size, MIN_EP_APERTURE);
>
> - /*
> - * roundup_pow_of_two() returns an unsigned long, which is not suited
> - * for 64bit values.
> - */
> - sz = 1ULL << fls64(sz - 1);
> + sz = roundup_pow_of_two64(sz);
> aperture = ilog2(sz) - 7; /* 128B -> 0, 256B -> 1, 512B -> 2, ... */
>
> if ((flags & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO) {
> diff --git a/include/linux/log2.h b/include/linux/log2.h
> index 83a4a3ca3e8a..db12d92ab6eb 100644
> --- a/include/linux/log2.h
> +++ b/include/linux/log2.h
> @@ -67,6 +67,24 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
> return 1UL << (fls_long(n) - 1);
> }
>
> +/**
> + * __roundup_pow_of_two64() - round 64bit value up to nearest power of two
> + * @n: value to round up
> + */
> +static inline __attribute__((const)) __u64 __roundup_pow_of_two64(__u64 n)
To be consistent with other functions in the same file (__ilog_u64) you may
want to rename this to __roundup_pow_of_two_u64.
Also do you know why u64 is used in some places and __u64 in others?
> +{
> + return 1UL << fls64(n - 1);
Does this need to be (and for the others):
return 1ULL << fls64(n - 1);
Notice that the PCI drivers you convert, all use 1ULL.
Thanks,
Andrew Murray
> +}
> +
> +/**
> + * __rounddown_pow_of_two64() - round 64bit value down to nearest power of two
> + * @n: value to round down
> + */
> +static inline __attribute__((const)) __u64 __rounddown_pow_of_two64(__u64 n)
> +{
> + return 1UL << (fls64(n) - 1);
> +}
> +
> /**
> * const_ilog2 - log base 2 of 32-bit or a 64-bit constant unsigned value
> * @n: parameter
> @@ -194,6 +212,40 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
> __rounddown_pow_of_two(n) \
> )
>
> +/**
> + * roundup_pow_of_two64 - round the given 64bit value up to nearest power of
> + * two
> + * @n: parameter
> + *
> + * round the given value up to the nearest power of two
> + * - the result is undefined when n == 0
> + * - this can be used to initialise global variables from constant data
> + */
> +#define roundup_pow_of_two64(n) \
> +( \
> + __builtin_constant_p(n) ? ( \
> + (n == 1) ? 1 : \
> + (1UL << (ilog2((n) - 1) + 1)) \
> + ) : \
> + __roundup_pow_of_two64(n) \
> +)
> +
> +/**
> + * rounddown_pow_of_two64 - round the given 64bit value down to nearest power
> + * of two
> + * @n: parameter
> + *
> + * round the given value down to the nearest power of two
> + * - the result is undefined when n == 0
> + * - this can be used to initialise global variables from constant data
> + */
> +#define rounddown_pow_of_two64(n) \
> +( \
> + __builtin_constant_p(n) ? ( \
> + (1UL << ilog2(n))) : \
> + __rounddown_pow_of_two64(n) \
> +)
> +
> static inline __attribute_const__
> int __order_base_2(unsigned long n)
> {
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index b9e1744999d9..a419530abd3e 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -15,6 +15,7 @@
> #include <linux/vmalloc.h>
> #include <linux/set_memory.h>
> #include <linux/swiotlb.h>
> +#include <linux/log2.h>
>
> /*
> * Most architectures use ZONE_DMA for the first 16 Megabytes, but some use it
> @@ -53,7 +54,7 @@ u64 dma_direct_get_required_mask(struct device *dev)
> {
> u64 max_dma = phys_to_dma_direct(dev, (max_pfn - 1) << PAGE_SHIFT);
>
> - return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
> + return rounddown_pow_of_two64(max_dma) * 2 - 1;
> }
>
> static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
> --
> 2.24.0
>
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