From 3dca0f42c7baaa4e01699629da13d6556f001ebe Mon Sep 17 00:00:00 2001 From: Matan Barak Date: Thu, 11 Dec 2014 10:57:53 +0200 Subject: [PATCH] net/mlx4_core: Use tasklet for user-space CQ completion events Previously, we've fired all our completion callbacks straight from our ISR. Some of those callbacks were lightweight (for example, mlx4_en's and IPoIB napi callbacks), but some of them did more work (for example, the user-space RDMA stack uverbs' completion handler). Besides that, doing more than the minimal work in ISR is generally considered wrong, it could even lead to a hard lockup of the system. Since when a lot of completion events are generated by the hardware, the loop over those events could be so long, that we'll get into a hard lockup by the system watchdog. In order to avoid that, add a new way of invoking completion events callbacks. In the interrupt itself, we add the CQs which receive completion event to a per-EQ list and schedule a tasklet. In the tasklet context we loop over all the CQs in the list and invoke the user callback. Signed-off-by: Matan Barak Signed-off-by: Or Gerlitz Signed-off-by: David S. Miller --- drivers/infiniband/hw/mlx4/cq.c | 5 ++- drivers/net/ethernet/mellanox/mlx4/cq.c | 50 +++++++++++++++++++++++ drivers/net/ethernet/mellanox/mlx4/eq.c | 16 +++++++- drivers/net/ethernet/mellanox/mlx4/mlx4.h | 12 ++++++ include/linux/mlx4/device.h | 5 +++ 5 files changed, 86 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/hw/mlx4/cq.c b/drivers/infiniband/hw/mlx4/cq.c index 1066eec854a..a3b70f6c403 100644 --- a/drivers/infiniband/hw/mlx4/cq.c +++ b/drivers/infiniband/hw/mlx4/cq.c @@ -233,7 +233,10 @@ struct ib_cq *mlx4_ib_create_cq(struct ib_device *ibdev, int entries, int vector if (err) goto err_dbmap; - cq->mcq.comp = mlx4_ib_cq_comp; + if (context) + cq->mcq.tasklet_ctx.comp = mlx4_ib_cq_comp; + else + cq->mcq.comp = mlx4_ib_cq_comp; cq->mcq.event = mlx4_ib_cq_event; if (context) diff --git a/drivers/net/ethernet/mellanox/mlx4/cq.c b/drivers/net/ethernet/mellanox/mlx4/cq.c index 56022d64783..e71f31387ac 100644 --- a/drivers/net/ethernet/mellanox/mlx4/cq.c +++ b/drivers/net/ethernet/mellanox/mlx4/cq.c @@ -52,6 +52,51 @@ #define MLX4_CQ_STATE_ARMED_SOL ( 6 << 8) #define MLX4_EQ_STATE_FIRED (10 << 8) +#define TASKLET_MAX_TIME 2 +#define TASKLET_MAX_TIME_JIFFIES msecs_to_jiffies(TASKLET_MAX_TIME) + +void mlx4_cq_tasklet_cb(unsigned long data) +{ + unsigned long flags; + unsigned long end = jiffies + TASKLET_MAX_TIME_JIFFIES; + struct mlx4_eq_tasklet *ctx = (struct mlx4_eq_tasklet *)data; + struct mlx4_cq *mcq, *temp; + + spin_lock_irqsave(&ctx->lock, flags); + list_splice_tail_init(&ctx->list, &ctx->process_list); + spin_unlock_irqrestore(&ctx->lock, flags); + + list_for_each_entry_safe(mcq, temp, &ctx->process_list, tasklet_ctx.list) { + list_del_init(&mcq->tasklet_ctx.list); + mcq->tasklet_ctx.comp(mcq); + if (atomic_dec_and_test(&mcq->refcount)) + complete(&mcq->free); + if (time_after(jiffies, end)) + break; + } + + if (!list_empty(&ctx->process_list)) + tasklet_schedule(&ctx->task); +} + +static void mlx4_add_cq_to_tasklet(struct mlx4_cq *cq) +{ + unsigned long flags; + struct mlx4_eq_tasklet *tasklet_ctx = cq->tasklet_ctx.priv; + + spin_lock_irqsave(&tasklet_ctx->lock, flags); + /* When migrating CQs between EQs will be implemented, please note + * that you need to sync this point. It is possible that + * while migrating a CQ, completions on the old EQs could + * still arrive. + */ + if (list_empty_careful(&cq->tasklet_ctx.list)) { + atomic_inc(&cq->refcount); + list_add_tail(&cq->tasklet_ctx.list, &tasklet_ctx->list); + } + spin_unlock_irqrestore(&tasklet_ctx->lock, flags); +} + void mlx4_cq_completion(struct mlx4_dev *dev, u32 cqn) { struct mlx4_cq *cq; @@ -292,6 +337,11 @@ int mlx4_cq_alloc(struct mlx4_dev *dev, int nent, cq->uar = uar; atomic_set(&cq->refcount, 1); init_completion(&cq->free); + cq->comp = mlx4_add_cq_to_tasklet; + cq->tasklet_ctx.priv = + &priv->eq_table.eq[cq->vector].tasklet_ctx; + INIT_LIST_HEAD(&cq->tasklet_ctx.list); + cq->irq = priv->eq_table.eq[cq->vector].irq; return 0; diff --git a/drivers/net/ethernet/mellanox/mlx4/eq.c b/drivers/net/ethernet/mellanox/mlx4/eq.c index d68b264cee4..3d275fbaf0e 100644 --- a/drivers/net/ethernet/mellanox/mlx4/eq.c +++ b/drivers/net/ethernet/mellanox/mlx4/eq.c @@ -450,7 +450,7 @@ static int mlx4_eq_int(struct mlx4_dev *dev, struct mlx4_eq *eq) { struct mlx4_priv *priv = mlx4_priv(dev); struct mlx4_eqe *eqe; - int cqn; + int cqn = -1; int eqes_found = 0; int set_ci = 0; int port; @@ -758,6 +758,13 @@ static int mlx4_eq_int(struct mlx4_dev *dev, struct mlx4_eq *eq) eq_set_ci(eq, 1); + /* cqn is 24bit wide but is initialized such that its higher bits + * are ones too. Thus, if we got any event, cqn's high bits should be off + * and we need to schedule the tasklet. + */ + if (!(cqn & ~0xffffff)) + tasklet_schedule(&eq->tasklet_ctx.task); + return eqes_found; } @@ -971,6 +978,12 @@ static int mlx4_create_eq(struct mlx4_dev *dev, int nent, eq->cons_index = 0; + INIT_LIST_HEAD(&eq->tasklet_ctx.list); + INIT_LIST_HEAD(&eq->tasklet_ctx.process_list); + spin_lock_init(&eq->tasklet_ctx.lock); + tasklet_init(&eq->tasklet_ctx.task, mlx4_cq_tasklet_cb, + (unsigned long)&eq->tasklet_ctx); + return err; err_out_free_mtt: @@ -1027,6 +1040,7 @@ static void mlx4_free_eq(struct mlx4_dev *dev, } } synchronize_irq(eq->irq); + tasklet_disable(&eq->tasklet_ctx.task); mlx4_mtt_cleanup(dev, &eq->mtt); for (i = 0; i < npages; ++i) diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4.h b/drivers/net/ethernet/mellanox/mlx4/mlx4.h index f48e7c3eecf..b67ef488c30 100644 --- a/drivers/net/ethernet/mellanox/mlx4/mlx4.h +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4.h @@ -43,6 +43,8 @@ #include #include #include +#include +#include #include #include @@ -373,6 +375,14 @@ struct mlx4_srq_context { __be64 db_rec_addr; }; +struct mlx4_eq_tasklet { + struct list_head list; + struct list_head process_list; + struct tasklet_struct task; + /* lock on completion tasklet list */ + spinlock_t lock; +}; + struct mlx4_eq { struct mlx4_dev *dev; void __iomem *doorbell; @@ -383,6 +393,7 @@ struct mlx4_eq { int nent; struct mlx4_buf_list *page_list; struct mlx4_mtt mtt; + struct mlx4_eq_tasklet tasklet_ctx; }; struct mlx4_slave_eqe { @@ -1146,6 +1157,7 @@ void mlx4_cmd_use_polling(struct mlx4_dev *dev); int mlx4_comm_cmd(struct mlx4_dev *dev, u8 cmd, u16 param, unsigned long timeout); +void mlx4_cq_tasklet_cb(unsigned long data); void mlx4_cq_completion(struct mlx4_dev *dev, u32 cqn); void mlx4_cq_event(struct mlx4_dev *dev, u32 cqn, int event_type); diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h index cf09e65c290..3951b5368d7 100644 --- a/include/linux/mlx4/device.h +++ b/include/linux/mlx4/device.h @@ -621,6 +621,11 @@ struct mlx4_cq { atomic_t refcount; struct completion free; + struct { + struct list_head list; + void (*comp)(struct mlx4_cq *); + void *priv; + } tasklet_ctx; }; struct mlx4_qp { -- 2.41.0