From 9ced69ca5296567033804950d8d2161f454c5012 Mon Sep 17 00:00:00 2001 From: Sean Hefty Date: Tue, 10 Jan 2012 23:53:41 +0000 Subject: [PATCH] RDMA/ucma: Discard all events for new connections until accepted After reporting a new connection request to user space, the rdma_ucm will discard subsequent events until the user has associated a user space idenfier with the kernel cm_id. This is needed to avoid reporting a reject/disconnect event to the user for a request that they may not have processed. The user space identifier is set once the user tries to accept the connection request. However, the following race exists in ucma_accept(): ctx->uid = cmd.uid; ret = rdma_accept(ctx->cm_id, ...); Once ctx->uid has been set, new events may be reported to the user. While the above mentioned race is avoided, there is an issue that the user _may_ receive a reject/disconnect event if rdma_accept() fails, depending on when the event is processed. To simplify the use of rdma_accept(), discard all events unless rdma_accept() succeeds. This problem was discovered based on questions from Roland Dreier . Signed-off-by: Sean Hefty Signed-off-by: Roland Dreier --- drivers/infiniband/core/ucma.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index b37b0c02a7b9..5034a87cc72d 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -808,9 +808,12 @@ static ssize_t ucma_accept(struct ucma_file *file, const char __user *inbuf, return PTR_ERR(ctx); if (cmd.conn_param.valid) { - ctx->uid = cmd.uid; ucma_copy_conn_param(&conn_param, &cmd.conn_param); + mutex_lock(&file->mut); ret = rdma_accept(ctx->cm_id, &conn_param); + if (!ret) + ctx->uid = cmd.uid; + mutex_unlock(&file->mut); } else ret = rdma_accept(ctx->cm_id, NULL);