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SubjectRe: [PATCH v4 7/8] linux/log2.h: Fix 64bit calculations in roundup/down_pow_two()
From
Date
On 03/12/2019 11:47 am, 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. It turns
> out ilog2() already handles 32/64bit calculations properly, and being
> the building block to the round functions we can rework them as a
> wrapper around it.

Neat! Although all the additional ULL casts this introduces seem
somewhat unwelcome - I suppose the (1ULL << (ilog2(n))) makes it
effectively always return unsigned long long now. Might it make sense to
cast the return value to typeof(n) to avoid this slightly non-obvious
behaviour (and the associated churn)?

Robin.

> Suggested-by: Robin Murphy <robin.murphy@arm.con>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---
> drivers/clk/clk-divider.c | 8 ++--
> drivers/clk/sunxi/clk-sunxi.c | 2 +-
> drivers/infiniband/hw/hfi1/chip.c | 4 +-
> drivers/infiniband/hw/hfi1/init.c | 4 +-
> drivers/infiniband/hw/mlx4/srq.c | 2 +-
> drivers/infiniband/hw/mthca/mthca_srq.c | 2 +-
> drivers/infiniband/sw/rxe/rxe_qp.c | 4 +-
> drivers/iommu/intel-iommu.c | 4 +-
> drivers/iommu/intel-svm.c | 4 +-
> drivers/iommu/intel_irq_remapping.c | 2 +-
> drivers/net/ethernet/amd/xgbe/xgbe-ethtool.c | 4 +-
> drivers/net/ethernet/marvell/sky2.c | 2 +-
> drivers/net/ethernet/rocker/rocker_hw.h | 4 +-
> drivers/net/ethernet/sfc/ef10.c | 2 +-
> drivers/net/ethernet/sfc/efx.h | 2 +-
> drivers/net/ethernet/sfc/falcon/efx.h | 2 +-
> drivers/pci/msi.c | 2 +-
> include/linux/log2.h | 44 +++++---------------
> kernel/kexec_core.c | 3 +-
> lib/rhashtable.c | 2 +-
> net/sunrpc/xprtrdma/verbs.c | 2 +-
> 21 files changed, 41 insertions(+), 64 deletions(-)
>
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index 098b2b01f0af..ba947e4c8193 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -222,7 +222,7 @@ static int _div_round_up(const struct clk_div_table *table,
> int div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
>
> if (flags & CLK_DIVIDER_POWER_OF_TWO)
> - div = __roundup_pow_of_two(div);
> + div = roundup_pow_of_two(div);
> if (table)
> div = _round_up_table(table, div);
>
> @@ -240,8 +240,8 @@ static int _div_round_closest(const struct clk_div_table *table,
> down = parent_rate / rate;
>
> if (flags & CLK_DIVIDER_POWER_OF_TWO) {
> - up = __roundup_pow_of_two(up);
> - down = __rounddown_pow_of_two(down);
> + up = roundup_pow_of_two(up);
> + down = rounddown_pow_of_two(down);
> } else if (table) {
> up = _round_up_table(table, up);
> down = _round_down_table(table, down);
> @@ -278,7 +278,7 @@ static int _next_div(const struct clk_div_table *table, int div,
> div++;
>
> if (flags & CLK_DIVIDER_POWER_OF_TWO)
> - return __roundup_pow_of_two(div);
> + return roundup_pow_of_two(div);
> if (table)
> return _round_up_table(table, div);
>
> diff --git a/drivers/clk/sunxi/clk-sunxi.c b/drivers/clk/sunxi/clk-sunxi.c
> index 27201fd26e44..faec99dc09c0 100644
> --- a/drivers/clk/sunxi/clk-sunxi.c
> +++ b/drivers/clk/sunxi/clk-sunxi.c
> @@ -311,7 +311,7 @@ static void sun6i_get_ahb1_factors(struct factors_request *req)
>
> calcm = DIV_ROUND_UP(div, 1 << calcp);
> } else {
> - calcp = __roundup_pow_of_two(div);
> + calcp = roundup_pow_of_two(div);
> calcp = calcp > 3 ? 3 : calcp;
> }
>
> diff --git a/drivers/infiniband/hw/hfi1/chip.c b/drivers/infiniband/hw/hfi1/chip.c
> index 9b1fb84a3d45..96b1d343c32f 100644
> --- a/drivers/infiniband/hw/hfi1/chip.c
> +++ b/drivers/infiniband/hw/hfi1/chip.c
> @@ -14199,10 +14199,10 @@ static int qos_rmt_entries(struct hfi1_devdata *dd, unsigned int *mp,
> max_by_vl = krcvqs[i];
> if (max_by_vl > 32)
> goto no_qos;
> - m = ilog2(__roundup_pow_of_two(max_by_vl));
> + m = ilog2(roundup_pow_of_two(max_by_vl));
>
> /* determine bits for vl */
> - n = ilog2(__roundup_pow_of_two(num_vls));
> + n = ilog2(roundup_pow_of_two(num_vls));
>
> /* reject if too much is used */
> if ((m + n) > 7)
> diff --git a/drivers/infiniband/hw/hfi1/init.c b/drivers/infiniband/hw/hfi1/init.c
> index 26b792bb1027..838c789c7cce 100644
> --- a/drivers/infiniband/hw/hfi1/init.c
> +++ b/drivers/infiniband/hw/hfi1/init.c
> @@ -467,7 +467,7 @@ int hfi1_create_ctxtdata(struct hfi1_pportdata *ppd, int numa,
> * MTU supported.
> */
> if (rcd->egrbufs.size < hfi1_max_mtu) {
> - rcd->egrbufs.size = __roundup_pow_of_two(hfi1_max_mtu);
> + rcd->egrbufs.size = roundup_pow_of_two(hfi1_max_mtu);
> hfi1_cdbg(PROC,
> "ctxt%u: eager bufs size too small. Adjusting to %u\n",
> rcd->ctxt, rcd->egrbufs.size);
> @@ -1959,7 +1959,7 @@ int hfi1_setup_eagerbufs(struct hfi1_ctxtdata *rcd)
> * to satisfy the "multiple of 8 RcvArray entries" requirement.
> */
> if (rcd->egrbufs.size <= (1 << 20))
> - rcd->egrbufs.rcvtid_size = max((unsigned long)round_mtu,
> + rcd->egrbufs.rcvtid_size = max((unsigned long long)round_mtu,
> rounddown_pow_of_two(rcd->egrbufs.size / 8));
>
> while (alloced_bytes < rcd->egrbufs.size &&
> diff --git a/drivers/infiniband/hw/mlx4/srq.c b/drivers/infiniband/hw/mlx4/srq.c
> index 8dcf6e3d9ae2..7e685600a7b3 100644
> --- a/drivers/infiniband/hw/mlx4/srq.c
> +++ b/drivers/infiniband/hw/mlx4/srq.c
> @@ -96,7 +96,7 @@ int mlx4_ib_create_srq(struct ib_srq *ib_srq,
> srq->msrq.max = roundup_pow_of_two(init_attr->attr.max_wr + 1);
> srq->msrq.max_gs = init_attr->attr.max_sge;
>
> - desc_size = max(32UL,
> + desc_size = max(32ULL,
> roundup_pow_of_two(sizeof (struct mlx4_wqe_srq_next_seg) +
> srq->msrq.max_gs *
> sizeof (struct mlx4_wqe_data_seg)));
> diff --git a/drivers/infiniband/hw/mthca/mthca_srq.c b/drivers/infiniband/hw/mthca/mthca_srq.c
> index a85935ccce88..0c2e14b4142a 100644
> --- a/drivers/infiniband/hw/mthca/mthca_srq.c
> +++ b/drivers/infiniband/hw/mthca/mthca_srq.c
> @@ -225,7 +225,7 @@ int mthca_alloc_srq(struct mthca_dev *dev, struct mthca_pd *pd,
> else
> srq->max = srq->max + 1;
>
> - ds = max(64UL,
> + ds = max(64ULL,
> roundup_pow_of_two(sizeof (struct mthca_next_seg) +
> srq->max_gs * sizeof (struct mthca_data_seg)));
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c
> index e2c6d1cedf41..040b707b0877 100644
> --- a/drivers/infiniband/sw/rxe/rxe_qp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_qp.c
> @@ -592,7 +592,7 @@ int rxe_qp_from_attr(struct rxe_qp *qp, struct ib_qp_attr *attr, int mask,
> int err;
>
> if (mask & IB_QP_MAX_QP_RD_ATOMIC) {
> - int max_rd_atomic = __roundup_pow_of_two(attr->max_rd_atomic);
> + int max_rd_atomic = roundup_pow_of_two(attr->max_rd_atomic);
>
> qp->attr.max_rd_atomic = max_rd_atomic;
> atomic_set(&qp->req.rd_atomic, max_rd_atomic);
> @@ -600,7 +600,7 @@ int rxe_qp_from_attr(struct rxe_qp *qp, struct ib_qp_attr *attr, int mask,
>
> if (mask & IB_QP_MAX_DEST_RD_ATOMIC) {
> int max_dest_rd_atomic =
> - __roundup_pow_of_two(attr->max_dest_rd_atomic);
> + roundup_pow_of_two(attr->max_dest_rd_atomic);
>
> qp->attr.max_dest_rd_atomic = max_dest_rd_atomic;
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 0c8d81f56a30..ce7c900bd666 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -1488,7 +1488,7 @@ static void iommu_flush_iotlb_psi(struct intel_iommu *iommu,
> unsigned long pfn, unsigned int pages,
> int ih, int map)
> {
> - unsigned int mask = ilog2(__roundup_pow_of_two(pages));
> + unsigned int mask = ilog2(roundup_pow_of_two(pages));
> uint64_t addr = (uint64_t)pfn << VTD_PAGE_SHIFT;
> u16 did = domain->iommu_did[iommu->seq_id];
>
> @@ -3390,7 +3390,7 @@ static unsigned long intel_alloc_iova(struct device *dev,
> /* Restrict dma_mask to the width that the iommu can handle */
> dma_mask = min_t(uint64_t, DOMAIN_MAX_ADDR(domain->gaw), dma_mask);
> /* Ensure we reserve the whole size-aligned region */
> - nrpages = __roundup_pow_of_two(nrpages);
> + nrpages = roundup_pow_of_two(nrpages);
>
> if (!dmar_forcedac && dma_mask > DMA_BIT_MASK(32)) {
> /*
> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> index 9b159132405d..602caca3cd1a 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -115,7 +115,7 @@ static void intel_flush_svm_range_dev (struct intel_svm *svm, struct intel_svm_d
> QI_EIOTLB_TYPE;
> desc.qw1 = 0;
> } else {
> - int mask = ilog2(__roundup_pow_of_two(pages));
> + int mask = ilog2(roundup_pow_of_two(pages));
>
> desc.qw0 = QI_EIOTLB_PASID(svm->pasid) |
> QI_EIOTLB_DID(sdev->did) |
> @@ -142,7 +142,7 @@ static void intel_flush_svm_range_dev (struct intel_svm *svm, struct intel_svm_d
> * for example, an "address" value of 0x12345f000 will
> * flush from 0x123440000 to 0x12347ffff (256KiB). */
> unsigned long last = address + ((unsigned long)(pages - 1) << VTD_PAGE_SHIFT);
> - unsigned long mask = __rounddown_pow_of_two(address ^ last);
> + unsigned long mask = rounddown_pow_of_two(address ^ last);
>
> desc.qw1 = QI_DEV_EIOTLB_ADDR((address & ~mask) |
> (mask - 1)) | QI_DEV_EIOTLB_SIZE;
> diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
> index 81e43c1df7ec..935657b2c661 100644
> --- a/drivers/iommu/intel_irq_remapping.c
> +++ b/drivers/iommu/intel_irq_remapping.c
> @@ -113,7 +113,7 @@ static int alloc_irte(struct intel_iommu *iommu,
> return -1;
>
> if (count > 1) {
> - count = __roundup_pow_of_two(count);
> + count = roundup_pow_of_two(count);
> mask = ilog2(count);
> }
>
> diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-ethtool.c b/drivers/net/ethernet/amd/xgbe/xgbe-ethtool.c
> index 6a757dadb5f1..fd5b12c23eaa 100644
> --- a/drivers/net/ethernet/amd/xgbe/xgbe-ethtool.c
> +++ b/drivers/net/ethernet/amd/xgbe/xgbe-ethtool.c
> @@ -680,13 +680,13 @@ static int xgbe_set_ringparam(struct net_device *netdev,
> return -EINVAL;
> }
>
> - rx = __rounddown_pow_of_two(ringparam->rx_pending);
> + rx = rounddown_pow_of_two(ringparam->rx_pending);
> if (rx != ringparam->rx_pending)
> netdev_notice(netdev,
> "rx ring parameter rounded to power of two: %u\n",
> rx);
>
> - tx = __rounddown_pow_of_two(ringparam->tx_pending);
> + tx = rounddown_pow_of_two(ringparam->tx_pending);
> if (tx != ringparam->tx_pending)
> netdev_notice(netdev,
> "tx ring parameter rounded to power of two: %u\n",
> diff --git a/drivers/net/ethernet/marvell/sky2.c b/drivers/net/ethernet/marvell/sky2.c
> index 5f56ee83e3b1..cc3a03b4a611 100644
> --- a/drivers/net/ethernet/marvell/sky2.c
> +++ b/drivers/net/ethernet/marvell/sky2.c
> @@ -4139,7 +4139,7 @@ static int sky2_set_coalesce(struct net_device *dev,
> */
> static unsigned long roundup_ring_size(unsigned long pending)
> {
> - return max(128ul, roundup_pow_of_two(pending+1));
> + return max(128ull, roundup_pow_of_two(pending+1));
> }
>
> static void sky2_get_ringparam(struct net_device *dev,
> diff --git a/drivers/net/ethernet/rocker/rocker_hw.h b/drivers/net/ethernet/rocker/rocker_hw.h
> index 59f1f8b690d2..d8de15509e2c 100644
> --- a/drivers/net/ethernet/rocker/rocker_hw.h
> +++ b/drivers/net/ethernet/rocker/rocker_hw.h
> @@ -88,8 +88,8 @@ enum rocker_dma_type {
> };
>
> /* Rocker DMA ring size limits and default sizes */
> -#define ROCKER_DMA_SIZE_MIN 2ul
> -#define ROCKER_DMA_SIZE_MAX 65536ul
> +#define ROCKER_DMA_SIZE_MIN 2ull
> +#define ROCKER_DMA_SIZE_MAX 65536ull
> #define ROCKER_DMA_CMD_DEFAULT_SIZE 32ul
> #define ROCKER_DMA_EVENT_DEFAULT_SIZE 32ul
> #define ROCKER_DMA_TX_DEFAULT_SIZE 64ul
> diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
> index 4d9bbccc6f89..4f4d9a5b3b75 100644
> --- a/drivers/net/ethernet/sfc/ef10.c
> +++ b/drivers/net/ethernet/sfc/ef10.c
> @@ -27,7 +27,7 @@ enum {
> };
> /* The maximum size of a shared RSS context */
> /* TODO: this should really be from the mcdi protocol export */
> -#define EFX_EF10_MAX_SHARED_RSS_CONTEXT_SIZE 64UL
> +#define EFX_EF10_MAX_SHARED_RSS_CONTEXT_SIZE 64ULL
>
> /* The filter table(s) are managed by firmware and we have write-only
> * access. When removing filters we must identify them to the
> diff --git a/drivers/net/ethernet/sfc/efx.h b/drivers/net/ethernet/sfc/efx.h
> index 2dd8d5002315..fea2add5860e 100644
> --- a/drivers/net/ethernet/sfc/efx.h
> +++ b/drivers/net/ethernet/sfc/efx.h
> @@ -52,7 +52,7 @@ void efx_schedule_slow_fill(struct efx_rx_queue *rx_queue);
>
> #define EFX_MAX_DMAQ_SIZE 4096UL
> #define EFX_DEFAULT_DMAQ_SIZE 1024UL
> -#define EFX_MIN_DMAQ_SIZE 512UL
> +#define EFX_MIN_DMAQ_SIZE 512ULL
>
> #define EFX_MAX_EVQ_SIZE 16384UL
> #define EFX_MIN_EVQ_SIZE 512UL
> diff --git a/drivers/net/ethernet/sfc/falcon/efx.h b/drivers/net/ethernet/sfc/falcon/efx.h
> index d3b4646545fa..0d16257156d6 100644
> --- a/drivers/net/ethernet/sfc/falcon/efx.h
> +++ b/drivers/net/ethernet/sfc/falcon/efx.h
> @@ -55,7 +55,7 @@ void ef4_schedule_slow_fill(struct ef4_rx_queue *rx_queue);
>
> #define EF4_MAX_DMAQ_SIZE 4096UL
> #define EF4_DEFAULT_DMAQ_SIZE 1024UL
> -#define EF4_MIN_DMAQ_SIZE 512UL
> +#define EF4_MIN_DMAQ_SIZE 512ULL
>
> #define EF4_MAX_EVQ_SIZE 16384UL
> #define EF4_MIN_EVQ_SIZE 512UL
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index c7709e49f0e4..f0391e88bc42 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -578,7 +578,7 @@ msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity *affd)
> entry->msi_attrib.maskbit = !!(control & PCI_MSI_FLAGS_MASKBIT);
> entry->msi_attrib.default_irq = dev->irq; /* Save IOAPIC IRQ */
> entry->msi_attrib.multi_cap = (control & PCI_MSI_FLAGS_QMASK) >> 1;
> - entry->msi_attrib.multiple = ilog2(__roundup_pow_of_two(nvec));
> + entry->msi_attrib.multiple = ilog2(roundup_pow_of_two(nvec));
>
> if (control & PCI_MSI_FLAGS_64BIT)
> entry->mask_pos = dev->msi_cap + PCI_MSI_MASK_64;
> diff --git a/include/linux/log2.h b/include/linux/log2.h
> index 83a4a3ca3e8a..53a727303dac 100644
> --- a/include/linux/log2.h
> +++ b/include/linux/log2.h
> @@ -47,26 +47,6 @@ bool is_power_of_2(unsigned long n)
> return (n != 0 && ((n & (n - 1)) == 0));
> }
>
> -/**
> - * __roundup_pow_of_two() - round up to nearest power of two
> - * @n: value to round up
> - */
> -static inline __attribute__((const))
> -unsigned long __roundup_pow_of_two(unsigned long n)
> -{
> - return 1UL << fls_long(n - 1);
> -}
> -
> -/**
> - * __rounddown_pow_of_two() - round down to nearest power of two
> - * @n: value to round down
> - */
> -static inline __attribute__((const))
> -unsigned long __rounddown_pow_of_two(unsigned long n)
> -{
> - return 1UL << (fls_long(n) - 1);
> -}
> -
> /**
> * const_ilog2 - log base 2 of 32-bit or a 64-bit constant unsigned value
> * @n: parameter
> @@ -170,14 +150,11 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
> * - the result is undefined when n == 0
> * - this can be used to initialise global variables from constant data
> */
> -#define roundup_pow_of_two(n) \
> -( \
> - __builtin_constant_p(n) ? ( \
> - (n == 1) ? 1 : \
> - (1UL << (ilog2((n) - 1) + 1)) \
> - ) : \
> - __roundup_pow_of_two(n) \
> - )
> +#define roundup_pow_of_two(n) \
> +( \
> + (__builtin_constant_p(n) && ((n) == 1)) ? \
> + 1 : (1ULL << (ilog2((n) - 1) + 1)) \
> +)
>
> /**
> * rounddown_pow_of_two - round the given value down to nearest power of two
> @@ -187,12 +164,11 @@ unsigned long __rounddown_pow_of_two(unsigned long n)
> * - the result is undefined when n == 0
> * - this can be used to initialise global variables from constant data
> */
> -#define rounddown_pow_of_two(n) \
> -( \
> - __builtin_constant_p(n) ? ( \
> - (1UL << ilog2(n))) : \
> - __rounddown_pow_of_two(n) \
> - )
> +#define rounddown_pow_of_two(n) \
> +( \
> + (__builtin_constant_p(n) && ((n) == 1)) ? \
> + 1 : (1ULL << (ilog2(n))) \
> +)
>
> static inline __attribute_const__
> int __order_base_2(unsigned long n)
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 15d70a90b50d..bb9efc6944a4 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -1094,7 +1094,8 @@ static int __init crash_notes_memory_init(void)
> * crash_notes is allocated inside one physical page.
> */
> size = sizeof(note_buf_t);
> - align = min(roundup_pow_of_two(sizeof(note_buf_t)), PAGE_SIZE);
> + align = min(roundup_pow_of_two(sizeof(note_buf_t)),
> + (unsigned long long)PAGE_SIZE);
>
> /*
> * Break compile if size is bigger than PAGE_SIZE since crash_notes
> diff --git a/lib/rhashtable.c b/lib/rhashtable.c
> index bdb7e4cadf05..70908678c7a8 100644
> --- a/lib/rhashtable.c
> +++ b/lib/rhashtable.c
> @@ -950,7 +950,7 @@ static size_t rounded_hashtable_size(const struct rhashtable_params *params)
>
> if (params->nelem_hint)
> retsize = max(roundup_pow_of_two(params->nelem_hint * 4 / 3),
> - (unsigned long)params->min_size);
> + (unsigned long long)params->min_size);
> else
> retsize = max(HASH_DEFAULT_SIZE,
> (unsigned long)params->min_size);
> diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
> index 77c7dd7f05e8..78fb8ccabddd 100644
> --- a/net/sunrpc/xprtrdma/verbs.c
> +++ b/net/sunrpc/xprtrdma/verbs.c
> @@ -1015,7 +1015,7 @@ struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt, size_t size,
> maxhdrsize = rpcrdma_fixed_maxsz + 3 +
> r_xprt->rx_ia.ri_max_segs * rpcrdma_readchunk_maxsz;
> maxhdrsize *= sizeof(__be32);
> - rb = rpcrdma_regbuf_alloc(__roundup_pow_of_two(maxhdrsize),
> + rb = rpcrdma_regbuf_alloc(roundup_pow_of_two(maxhdrsize),
> DMA_TO_DEVICE, flags);
> if (!rb)
> goto out2;
>

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