The mlx4_ib_cq_comp dispatching was racy and this is fixed by using rcu locking. However, that introduced regression in ib port failure tests, so changing to rwlock. rcu_XXX api are used to synchronize threads and use preempt_disable/enable to make sure that no thread cross other thread but is not safe for interrupts routines. In this case we are in inteerupt context: mlx4_msi_x_interrupt -> mlx4_eq_int -> mlx4_cq_completion, so can't use rcu_XXX to protect this code.
The stack is below: crash> bt PID: 32068 TASK: ffff880ed14405c0 CPU: 20 COMMAND: "kworker/u:1" #0 [ffff880ec7c01a00] __schedule at ffffffff81506664 #1 [ffff880ec7c01b18] schedule at ffffffff81506d45 #2 [ffff880ec7c01b28] schedule_timeout at ffffffff8150719c #3 [ffff880ec7c01bd8] wait_for_common at ffffffff81506bcd #4 [ffff880ec7c01c68] wait_for_completion at ffffffff81506cfd #5 [ffff880ec7c01c78] synchronize_sched at ffffffff810dda48 #6 [ffff880ec7c01cc8] mlx4_cq_free at ffffffffa027e67e [mlx4_core] #7 [ffff880ec7c01cf8] mlx4_ib_destroy_cq at ffffffffa03238a3 [mlx4_ib] #8 [ffff880ec7c01d18] ib_destroy_cq at ffffffffa0301c9e [ib_core] #9 [ffff880ec7c01d28] rds_ib_conn_shutdown at ffffffffa041cf5d [rds_rdma] #10 [ffff880ec7c01dd8] rds_conn_shutdown at ffffffffa02b7f18 [rds] #11 [ffff880ec7c01e38] rds_shutdown_worker at ffffffffa02bd14a [rds] #12 [ffff880ec7c01e58] process_one_work at ffffffff8108c3b9 #13 [ffff880ec7c01ea8] worker_thread at ffffffff8108ccfa #14 [ffff880ec7c01ee8] kthread at ffffffff810912d7 #15 [ffff880ec7c01f48] kernel_thread_helper at ffffffff815123c4 Signed-off-by: Zheng Li <zheng.x...@oracle.com> Signed-off-by: Joe Jin <joe....@oracle.com> Signed-off-by: Guru <guru.anbalag...@oracle.com> Signed-off-by: John Sobecki <john.sobe...@oracle.com> --- drivers/net/ethernet/mellanox/mlx4/cq.c | 26 +++++++++++++++----------- drivers/net/ethernet/mellanox/mlx4/mlx4.h | 2 +- 2 files changed, 16 insertions(+), 12 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/cq.c b/drivers/net/ethernet/mellanox/mlx4/cq.c index 56022d6..8b3b849 100644 --- a/drivers/net/ethernet/mellanox/mlx4/cq.c +++ b/drivers/net/ethernet/mellanox/mlx4/cq.c @@ -54,15 +54,19 @@ void mlx4_cq_completion(struct mlx4_dev *dev, u32 cqn) { + struct mlx4_cq_table *cq_table = &mlx4_priv(dev)->cq_table; struct mlx4_cq *cq; - cq = radix_tree_lookup(&mlx4_priv(dev)->cq_table.tree, - cqn & (dev->caps.num_cqs - 1)); + read_lock(&cq_table->lock); + + cq = radix_tree_lookup(&cq_table->tree, cqn & (dev->caps.num_cqs - 1)); if (!cq) { mlx4_dbg(dev, "Completion event for bogus CQ %08x\n", cqn); return; } + read_unlock(&cq_table->lock); + ++cq->arm_sn; cq->comp(cq); @@ -73,13 +77,13 @@ void mlx4_cq_event(struct mlx4_dev *dev, u32 cqn, int event_type) struct mlx4_cq_table *cq_table = &mlx4_priv(dev)->cq_table; struct mlx4_cq *cq; - spin_lock(&cq_table->lock); + read_lock(&cq_table->lock); cq = radix_tree_lookup(&cq_table->tree, cqn & (dev->caps.num_cqs - 1)); if (cq) atomic_inc(&cq->refcount); - spin_unlock(&cq_table->lock); + read_unlock(&cq_table->lock); if (!cq) { mlx4_warn(dev, "Async event for bogus CQ %08x\n", cqn); @@ -256,9 +260,9 @@ int mlx4_cq_alloc(struct mlx4_dev *dev, int nent, if (err) return err; - spin_lock_irq(&cq_table->lock); + write_lock_irq(&cq_table->lock); err = radix_tree_insert(&cq_table->tree, cq->cqn, cq); - spin_unlock_irq(&cq_table->lock); + write_unlock_irq(&cq_table->lock); if (err) goto err_icm; @@ -297,9 +301,9 @@ int mlx4_cq_alloc(struct mlx4_dev *dev, int nent, return 0; err_radix: - spin_lock_irq(&cq_table->lock); + write_lock_irq(&cq_table->lock); radix_tree_delete(&cq_table->tree, cq->cqn); - spin_unlock_irq(&cq_table->lock); + write_unlock_irq(&cq_table->lock); err_icm: mlx4_cq_free_icm(dev, cq->cqn); @@ -320,9 +324,9 @@ void mlx4_cq_free(struct mlx4_dev *dev, struct mlx4_cq *cq) synchronize_irq(priv->eq_table.eq[cq->vector].irq); - spin_lock_irq(&cq_table->lock); + write_lock_irq(&cq_table->lock); radix_tree_delete(&cq_table->tree, cq->cqn); - spin_unlock_irq(&cq_table->lock); + write_unlock_irq(&cq_table->lock); if (atomic_dec_and_test(&cq->refcount)) complete(&cq->free); @@ -337,7 +341,7 @@ int mlx4_init_cq_table(struct mlx4_dev *dev) struct mlx4_cq_table *cq_table = &mlx4_priv(dev)->cq_table; int err; - spin_lock_init(&cq_table->lock); + rwlock_init(&cq_table->lock); INIT_RADIX_TREE(&cq_table->tree, GFP_ATOMIC); if (mlx4_is_slave(dev)) return 0; diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4.h b/drivers/net/ethernet/mellanox/mlx4/mlx4.h index de10dbb..42e2348 100644 --- a/drivers/net/ethernet/mellanox/mlx4/mlx4.h +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4.h @@ -642,7 +642,7 @@ struct mlx4_mr_table { struct mlx4_cq_table { struct mlx4_bitmap bitmap; - spinlock_t lock; + rwlock_t lock; struct radix_tree_root tree; struct mlx4_icm_table table; struct mlx4_icm_table cmpt_table; -- 1.7.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html