On Tue, 2019-08-20 at 15:32 -0700, Matthew Wilcox wrote:
> From: "Matthew Wilcox (Oracle)" <wi...@infradead.org>
>
> This XArray appears to be modifiable from interrupt context, so we
> have
> to be a little more careful with the locking. However, the lookup
> can
> be done without the spinlock held. I cannot determine whether
> mlx4_qp_alloc() is allowed to sleep, so I've retained the GFP_ATOMIC
> there, but it could be turned into GFP_KERNEL if the callers can
> tolerate it sleeping.
>
> Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org>
> ---
> drivers/net/ethernet/mellanox/mlx4/mlx4.h | 3 +-
> drivers/net/ethernet/mellanox/mlx4/qp.c | 37 ++++++---------------
> --
> include/linux/mlx4/device.h | 4 +--
> include/linux/mlx4/qp.h | 2 +-
> 4 files changed, 14 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4.h
> b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
> index b6fe22bee9f4..aaece8480da7 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/mlx4.h
> +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4.h
> @@ -38,7 +38,7 @@
> #define MLX4_H
>
> #include <linux/mutex.h>
> -#include <linux/radix-tree.h>
> +#include <linux/xarray.h>
> #include <linux/rbtree.h>
> #include <linux/timer.h>
> #include <linux/semaphore.h>
> @@ -716,7 +716,6 @@ struct mlx4_qp_table {
> u32 zones_uids[MLX4_QP_TABLE_ZONE_NUM];
> u32 rdmarc_base;
> int rdmarc_shift;
> - spinlock_t lock;
> struct mlx4_icm_table qp_table;
> struct mlx4_icm_table auxc_table;
> struct mlx4_icm_table altc_table;
> diff --git a/drivers/net/ethernet/mellanox/mlx4/qp.c
> b/drivers/net/ethernet/mellanox/mlx4/qp.c
> index 427e7a31862c..4659ecec12c1 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/qp.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/qp.c
> @@ -48,16 +48,13 @@
>
> void mlx4_qp_event(struct mlx4_dev *dev, u32 qpn, int event_type)
> {
> - struct mlx4_qp_table *qp_table = &mlx4_priv(dev)->qp_table;
> struct mlx4_qp *qp;
>
> - spin_lock(&qp_table->lock);
> -
> + xa_lock(&dev->qp_table);
> qp = __mlx4_qp_lookup(dev, qpn);
> if (qp)
> refcount_inc(&qp->refcount);
> -
> - spin_unlock(&qp_table->lock);
> + xa_unlock(&dev->qp_table);
>
> if (!qp) {
> mlx4_dbg(dev, "Async event for none existent QP
> %08x\n", qpn);
> @@ -390,21 +387,11 @@ static void mlx4_qp_free_icm(struct mlx4_dev
> *dev, int qpn)
>
> struct mlx4_qp *mlx4_qp_lookup(struct mlx4_dev *dev, u32 qpn)
> {
> - struct mlx4_qp_table *qp_table = &mlx4_priv(dev)->qp_table;
> - struct mlx4_qp *qp;
> -
> - spin_lock_irq(&qp_table->lock);
> -
> - qp = __mlx4_qp_lookup(dev, qpn);
> -
> - spin_unlock_irq(&qp_table->lock);
> - return qp;
> + return __mlx4_qp_lookup(dev, qpn);
> }
>
> int mlx4_qp_alloc(struct mlx4_dev *dev, int qpn, struct mlx4_qp *qp)
> {
> - struct mlx4_priv *priv = mlx4_priv(dev);
> - struct mlx4_qp_table *qp_table = &priv->qp_table;
> int err;
>
> if (!qpn)
> @@ -416,10 +403,9 @@ int mlx4_qp_alloc(struct mlx4_dev *dev, int qpn,
> struct mlx4_qp *qp)
> if (err)
> return err;
>
> - spin_lock_irq(&qp_table->lock);
> - err = radix_tree_insert(&dev->qp_table_tree, qp->qpn &
> - (dev->caps.num_qps - 1), qp);
> - spin_unlock_irq(&qp_table->lock);
> + err = xa_err(xa_store_irq(&dev->qp_table,
> + qp->qpn & (dev->caps.num_qps - 1),
> + qp, GFP_ATOMIC));
mlx4_qp_alloc might sleep, so GFP_KERNEL here.
> if (err)
> goto err_icm;
>
> @@ -512,12 +498,11 @@ EXPORT_SYMBOL_GPL(mlx4_update_qp);
>
> void mlx4_qp_remove(struct mlx4_dev *dev, struct mlx4_qp *qp)
> {
> - struct mlx4_qp_table *qp_table = &mlx4_priv(dev)->qp_table;
> unsigned long flags;
>
> - spin_lock_irqsave(&qp_table->lock, flags);
> - radix_tree_delete(&dev->qp_table_tree, qp->qpn & (dev-
> >caps.num_qps - 1));
> - spin_unlock_irqrestore(&qp_table->lock, flags);
> + xa_lock_irqsave(&dev->qp_table, flags);
> + __xa_erase(&dev->qp_table, qp->qpn & (dev->caps.num_qps - 1));
> + xa_unlock_irqrestore(&dev->qp_table, flags);
> }
> EXPORT_SYMBOL_GPL(mlx4_qp_remove);
>
> @@ -760,7 +745,6 @@ static void mlx4_cleanup_qp_zones(struct mlx4_dev
> *dev)
>
> int mlx4_init_qp_table(struct mlx4_dev *dev)
> {
> - struct mlx4_qp_table *qp_table = &mlx4_priv(dev)->qp_table;
> int err;
> int reserved_from_top = 0;
> int reserved_from_bot;
> @@ -770,8 +754,7 @@ int mlx4_init_qp_table(struct mlx4_dev *dev)
> u32 max_table_offset = dev->caps.dmfs_high_rate_qpn_base +
> dev->caps.dmfs_high_rate_qpn_range;
>
> - spin_lock_init(&qp_table->lock);
> - INIT_RADIX_TREE(&dev->qp_table_tree, GFP_ATOMIC);
> + xa_init_flags(&dev->qp_table, XA_FLAGS_LOCK_IRQ);
> if (mlx4_is_slave(dev))
> return 0;
>
> diff --git a/include/linux/mlx4/device.h
> b/include/linux/mlx4/device.h
> index 36e412c3d657..acffca7d9f00 100644
> --- a/include/linux/mlx4/device.h
> +++ b/include/linux/mlx4/device.h
> @@ -36,7 +36,7 @@
> #include <linux/if_ether.h>
> #include <linux/pci.h>
> #include <linux/completion.h>
> -#include <linux/radix-tree.h>
> +#include <linux/xarray.h>
> #include <linux/cpu_rmap.h>
> #include <linux/crash_dump.h>
>
> @@ -889,7 +889,7 @@ struct mlx4_dev {
> struct mlx4_caps caps;
> struct mlx4_phys_caps phys_caps;
> struct mlx4_quotas quotas;
> - struct radix_tree_root qp_table_tree;
> + struct xarray qp_table;
> u8 rev_id;
> u8 port_random_macs;
> char board_id[MLX4_BOARD_ID_LEN];
> diff --git a/include/linux/mlx4/qp.h b/include/linux/mlx4/qp.h
> index 8e2828d48d7f..6c3ec3197a10 100644
> --- a/include/linux/mlx4/qp.h
> +++ b/include/linux/mlx4/qp.h
> @@ -488,7 +488,7 @@ int mlx4_qp_to_ready(struct mlx4_dev *dev, struct
> mlx4_mtt *mtt,
>
> static inline struct mlx4_qp *__mlx4_qp_lookup(struct mlx4_dev *dev,
> u32 qpn)
> {
> - return radix_tree_lookup(&dev->qp_table_tree, qpn & (dev-
> >caps.num_qps - 1));
> + return xa_load(&dev->qp_table, qpn & (dev->caps.num_qps - 1));
> }
>
> void mlx4_qp_remove(struct mlx4_dev *dev, struct mlx4_qp *qp);
