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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: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Jason Gunthorpe 2020-08-18 15:05:18 +03:00
parent 95fe51096b
commit d114c6feed
3 changed files with 35 additions and 7 deletions
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25
drivers/infiniband/core/cma.c
View File

@ -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;

12
drivers/infiniband/core/ucma.c
View File

@ -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);

5
include/rdma/rdma_cm.h
View File

@ -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)