Commit d114c6fe authored by Jason Gunthorpe's avatar Jason Gunthorpe
Browse files

RDMA/cma: Add missing locking to rdma_accept() 

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.

Link: https://lore.kernel.org/r/20200818120526.702120-7-leon@kernel.org


Signed-off-by: default avatarLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 95fe5109

drivers/infiniband/core/cma.c

+22 −3
Original line number Diff line number Diff line
@@ -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;

drivers/infiniband/core/ucma.c

+8 −4
Original line number Diff line number Diff line
@@ -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);

include/rdma/rdma_cm.h

+5 −0
Original line number Diff line number Diff line
@@ -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)

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