From: Jason Gunthorpe <jgg@xxxxxxxxxx>
In almost all cases rdma_accept() is called under the handler_mutex by
ULPs from their handler callbacks. The one exception was ucma which did
not get the handler_mutex.
To improve the understand-ability of the locking scheme obtain the mutex
for ucma as well.
This improves how ucma works by allowing it to directly use handler_mutex
for some of its internal locking against the handler callbacks intead of
the global file->mut lock.
There does not seem to be a serious bug here, other than a DISCONNECT event
can be delivered concurrently with accept succeeding.
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
---
drivers/infiniband/core/cma.c | 25 ++++++++++++++++++++++---
drivers/infiniband/core/ucma.c | 12 ++++++++----
include/rdma/rdma_cm.h | 5 +++++
3 files changed, 35 insertions(+), 7 deletions(-)
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 26de0dab60bb..78641858abe2 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -4154,14 +4154,15 @@ static int cma_send_sidr_rep(struct rdma_id_private *id_priv,
int __rdma_accept(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
const char *caller)
{
- struct rdma_id_private *id_priv;
+ struct rdma_id_private *id_priv =
+ container_of(id, struct rdma_id_private, id);
int ret;
- id_priv = container_of(id, struct rdma_id_private, id);
+ lockdep_assert_held(&id_priv->handler_mutex);
rdma_restrack_set_task(&id_priv->res, caller);
- if (!cma_comp(id_priv, RDMA_CM_CONNECT))
+ if (READ_ONCE(id_priv->state) != RDMA_CM_CONNECT)
return -EINVAL;
if (!id->qp && conn_param) {
@@ -4214,6 +4215,24 @@ int __rdma_accept_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
}
EXPORT_SYMBOL(__rdma_accept_ece);
+void rdma_lock_handler(struct rdma_cm_id *id)
+{
+ struct rdma_id_private *id_priv =
+ container_of(id, struct rdma_id_private, id);
+
+ mutex_lock(&id_priv->handler_mutex);
+}
+EXPORT_SYMBOL(rdma_lock_handler);
+
+void rdma_unlock_handler(struct rdma_cm_id *id)
+{
+ struct rdma_id_private *id_priv =
+ container_of(id, struct rdma_id_private, id);
+
+ mutex_unlock(&id_priv->handler_mutex);
+}
+EXPORT_SYMBOL(rdma_unlock_handler);
+
int rdma_notify(struct rdma_cm_id *id, enum ib_event_type event)
{
struct rdma_id_private *id_priv;
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index dd12931f3038..add1ece38739 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -1162,16 +1162,20 @@ static ssize_t ucma_accept(struct ucma_file *file, const char __user *inbuf,
if (cmd.conn_param.valid) {
ucma_copy_conn_param(ctx->cm_id, &conn_param, &cmd.conn_param);
- mutex_lock(&file->mut);
mutex_lock(&ctx->mutex);
+ rdma_lock_handler(ctx->cm_id);
ret = __rdma_accept_ece(ctx->cm_id, &conn_param, NULL, &ece);
- mutex_unlock(&ctx->mutex);
- if (!ret)
+ if (!ret) {
+ /* The uid must be set atomically with the handler */
ctx->uid = cmd.uid;
- mutex_unlock(&file->mut);
+ }
+ rdma_unlock_handler(ctx->cm_id);
+ mutex_unlock(&ctx->mutex);
} else {
mutex_lock(&ctx->mutex);
+ rdma_lock_handler(ctx->cm_id);
ret = __rdma_accept_ece(ctx->cm_id, NULL, NULL, &ece);
+ rdma_unlock_handler(ctx->cm_id);
mutex_unlock(&ctx->mutex);
}
ucma_put_ctx(ctx);
diff --git a/include/rdma/rdma_cm.h b/include/rdma/rdma_cm.h
index cf5da2ae49bf..c1334c9a7aa8 100644
--- a/include/rdma/rdma_cm.h
+++ b/include/rdma/rdma_cm.h
@@ -253,6 +253,8 @@ int rdma_listen(struct rdma_cm_id *id, int backlog);
int __rdma_accept(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
const char *caller);
+void rdma_lock_handler(struct rdma_cm_id *id);
+void rdma_unlock_handler(struct rdma_cm_id *id);
int __rdma_accept_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
const char *caller, struct rdma_ucm_ece *ece);
@@ -270,6 +272,9 @@ int __rdma_accept_ece(struct rdma_cm_id *id, struct rdma_conn_param *conn_param,
* In the case of error, a reject message is sent to the remote side and the
* state of the qp associated with the id is modified to error, such that any
* previously posted receive buffers would be flushed.
+ *
+ * This function is for use by kernel ULPs and must be called from under the
+ * handler callback.
*/
#define rdma_accept(id, conn_param) \
__rdma_accept((id), (conn_param), KBUILD_MODNAME)
--
2.26.2
