Patch "RDMA/rtrs-srv: Do not pass a valid pointer to PTR_ERR()" has been added to the 5.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    RDMA/rtrs-srv: Do not pass a valid pointer to PTR_ERR()

to the 5.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     rdma-rtrs-srv-do-not-pass-a-valid-pointer-to-ptr_err.patch
and it can be found in the queue-5.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 01f8a251dc84468534e8c0db8714c3d3ebd04ee3
Author: Jack Wang <jinpu.wang@xxxxxxxxxxxxxxx>
Date:   Tue Feb 16 15:38:07 2021 +0100

    RDMA/rtrs-srv: Do not pass a valid pointer to PTR_ERR()
    
    [ Upstream commit ed408529679737a9a7ad816c8de5d59ba104bb11 ]
    
    smatch gives the warning:
    
      drivers/infiniband/ulp/rtrs/rtrs-srv.c:1805 rtrs_rdma_connect() warn: passing zero to 'PTR_ERR'
    
    Which is trying to say smatch has shown that srv is not an error pointer
    and thus cannot be passed to PTR_ERR.
    
    The solution is to move the list_add() down after full initilization of
    rtrs_srv. To avoid holding the srv_mutex too long, only hold it during the
    list operation as suggested by Leon.
    
    Fixes: 03e9b33a0fd6 ("RDMA/rtrs: Only allow addition of path to an already established session")
    Link: https://lore.kernel.org/r/20210216143807.65923-1-jinpu.wang@xxxxxxxxxxxxxxx
    Reported-by: kernel test robot <lkp@xxxxxxxxx>
    Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
    Signed-off-by: Jack Wang <jinpu.wang@xxxxxxxxxxxxxxx>
    Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv.c b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
index 77ec87f1a660b..3850d2a938f8e 100644
--- a/drivers/infiniband/ulp/rtrs/rtrs-srv.c
+++ b/drivers/infiniband/ulp/rtrs/rtrs-srv.c
@@ -1348,21 +1348,18 @@ static struct rtrs_srv *get_or_create_srv(struct rtrs_srv_ctx *ctx,
 			return srv;
 		}
 	}
+	mutex_unlock(&ctx->srv_mutex);
 	/*
 	 * If this request is not the first connection request from the
 	 * client for this session then fail and return error.
 	 */
-	if (!first_conn) {
-		mutex_unlock(&ctx->srv_mutex);
+	if (!first_conn)
 		return ERR_PTR(-ENXIO);
-	}
 
 	/* need to allocate a new srv */
 	srv = kzalloc(sizeof(*srv), GFP_KERNEL);
-	if  (!srv) {
-		mutex_unlock(&ctx->srv_mutex);
+	if  (!srv)
 		return ERR_PTR(-ENOMEM);
-	}
 
 	INIT_LIST_HEAD(&srv->paths_list);
 	mutex_init(&srv->paths_mutex);
@@ -1372,8 +1369,6 @@ static struct rtrs_srv *get_or_create_srv(struct rtrs_srv_ctx *ctx,
 	srv->ctx = ctx;
 	device_initialize(&srv->dev);
 	srv->dev.release = rtrs_srv_dev_release;
-	list_add(&srv->ctx_list, &ctx->srv_list);
-	mutex_unlock(&ctx->srv_mutex);
 
 	srv->chunks = kcalloc(srv->queue_depth, sizeof(*srv->chunks),
 			      GFP_KERNEL);
@@ -1386,6 +1381,9 @@ static struct rtrs_srv *get_or_create_srv(struct rtrs_srv_ctx *ctx,
 			goto err_free_chunks;
 	}
 	refcount_set(&srv->refcount, 1);
+	mutex_lock(&ctx->srv_mutex);
+	list_add(&srv->ctx_list, &ctx->srv_list);
+	mutex_unlock(&ctx->srv_mutex);
 
 	return srv;
 
@@ -1800,11 +1798,7 @@ static int rtrs_rdma_connect(struct rdma_cm_id *cm_id,
 	}
 	recon_cnt = le16_to_cpu(msg->recon_cnt);
 	srv = get_or_create_srv(ctx, &msg->paths_uuid, msg->first_conn);
-	/*
-	 * "refcount == 0" happens if a previous thread calls get_or_create_srv
-	 * allocate srv, but chunks of srv are not allocated yet.
-	 */
-	if (IS_ERR(srv) || refcount_read(&srv->refcount) == 0) {
+	if (IS_ERR(srv)) {
 		err = PTR_ERR(srv);
 		goto reject_w_err;
 	}