]> nv-tegra.nvidia Code Review - linux-2.6.git/commitdiff
RDMA/cma: Fix device removal race
authorKrishna Kumar <krkumar2@in.ibm.com>
Fri, 29 Sep 2006 18:51:49 +0000 (11:51 -0700)
committerRoland Dreier <rolandd@cisco.com>
Mon, 2 Oct 2006 21:52:15 +0000 (14:52 -0700)
The race is as follows:

A process : cma_process_remove() calls cma_remove_id_dev(),
    which sets id state to CMA_DEVICE_REMOVAL and
    calls wait_event(dev_remove).

B process : cma_req_handler() had incremented dev_remove,
    and calls cma_acquire_ib_dev() and on failure
    calls cma_release_remove(), which does a
    wake_up of cma_process_remove(). Then
    cma_req_handler() calls rdma_destroy_id();

A Process : cma_remove_id_dev() gets woken and checks the
    state of id, and since it is still (wrongly)
    CMA_DEVICE_REMOVAL, it calls notify_user(id)
    and if that fails, the caller - cma_process_remove()
    calls rdma_destroy_id(id). Two processes can
    call rdma_destroy_id(), resulting in one
    de-referencing kfreed id_priv.

Fix is for process B to set CMA_DESTROYING in cma_req_handler()
so that process A will return instead of doing a rdma_destroy_id().

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
drivers/infiniband/core/cma.c

index 69bb0892e8876ca1b56521086070908f7c96ef54..f383a4f50ab01289069365f89dfdfcfbbfb56a20 100644 (file)
@@ -932,6 +932,7 @@ static int cma_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *ib_event)
        mutex_unlock(&lock);
        if (ret) {
                ret = -ENODEV;
+               cma_exch(conn_id, CMA_DESTROYING);
                cma_release_remove(conn_id);
                rdma_destroy_id(&conn_id->id);
                goto out;