From: Jason Gunthorpe jgg@mellanox.com
[ Upstream commit e8dc4e885c459343970b25acd9320fe9ee5492e7 ]
xa_alloc_cyclic() is a SMP release to be paired with some later acquire during xa_load() as part of cm_acquire_id().
As such, xa_alloc_cyclic() must be done after the cm_id is fully initialized, in particular, it absolutely must be after the refcount_set(), otherwise the refcount_inc() in cm_acquire_id() may not see the set.
As there are several cases where a reader will be able to use the id.local_id after cm_acquire_id in the IB_CM_IDLE state there needs to be an unfortunate split into a NULL allocate and a finalizing xa_store.
Fixes: a977049dacde ("[PATCH] IB: Add the kernel CM implementation") Link: https://lore.kernel.org/r/20200310092545.251365-2-leon@kernel.org Signed-off-by: Leon Romanovsky leonro@mellanox.com Signed-off-by: Jason Gunthorpe jgg@mellanox.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/infiniband/core/cm.c | 27 +++++++++++---------------- 1 file changed, 11 insertions(+), 16 deletions(-)
diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c index 4decc1d4cc997..1c7984bae7ab2 100644 --- a/drivers/infiniband/core/cm.c +++ b/drivers/infiniband/core/cm.c @@ -571,18 +571,6 @@ static int cm_init_av_by_path(struct sa_path_rec *path, return 0; }
-static int cm_alloc_id(struct cm_id_private *cm_id_priv) -{ - int err; - u32 id; - - err = xa_alloc_cyclic_irq(&cm.local_id_table, &id, cm_id_priv, - xa_limit_32b, &cm.local_id_next, GFP_KERNEL); - - cm_id_priv->id.local_id = (__force __be32)id ^ cm.random_id_operand; - return err; -} - static u32 cm_local_id(__be32 local_id) { return (__force u32) (local_id ^ cm.random_id_operand); @@ -836,6 +824,7 @@ struct ib_cm_id *ib_create_cm_id(struct ib_device *device, void *context) { struct cm_id_private *cm_id_priv; + u32 id; int ret;
cm_id_priv = kzalloc(sizeof *cm_id_priv, GFP_KERNEL); @@ -847,9 +836,6 @@ struct ib_cm_id *ib_create_cm_id(struct ib_device *device, cm_id_priv->id.cm_handler = cm_handler; cm_id_priv->id.context = context; cm_id_priv->id.remote_cm_qpn = 1; - ret = cm_alloc_id(cm_id_priv); - if (ret) - goto error;
spin_lock_init(&cm_id_priv->lock); init_completion(&cm_id_priv->comp); @@ -858,11 +844,20 @@ struct ib_cm_id *ib_create_cm_id(struct ib_device *device, INIT_LIST_HEAD(&cm_id_priv->altr_list); atomic_set(&cm_id_priv->work_count, -1); refcount_set(&cm_id_priv->refcount, 1); + + ret = xa_alloc_cyclic_irq(&cm.local_id_table, &id, NULL, xa_limit_32b, + &cm.local_id_next, GFP_KERNEL); + if (ret) + goto error; + cm_id_priv->id.local_id = (__force __be32)id ^ cm.random_id_operand; + xa_store_irq(&cm.local_id_table, cm_local_id(cm_id_priv->id.local_id), + cm_id_priv, GFP_KERNEL); + return &cm_id_priv->id;
error: kfree(cm_id_priv); - return ERR_PTR(-ENOMEM); + return ERR_PTR(ret); } EXPORT_SYMBOL(ib_create_cm_id);