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    Subject[PATCH 5.4 326/344] nvmet: Pass lockdep expression to RCU lists
    Date
    From: Amol Grover <frextrite@gmail.com>

    [ Upstream commit 4ac76436a6d07dec1c3c766f234aa787a16e8f65 ]

    ctrl->subsys->namespaces and subsys->namespaces are traversed with
    list_for_each_entry_rcu outside an RCU read-side critical section but
    under the protection of ctrl->subsys->lock and subsys->lock respectively.

    Hence, add the corresponding lockdep expression to the list traversal
    primitive to silence false-positive lockdep warnings, and harden RCU
    lists.

    Reported-by: kbuild test robot <lkp@intel.com>
    Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
    Signed-off-by: Amol Grover <frextrite@gmail.com>
    Signed-off-by: Keith Busch <kbusch@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/nvme/target/core.c | 6 ++++--
    1 file changed, 4 insertions(+), 2 deletions(-)

    diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
    index 3a67e244e5685..57a4062cbb59e 100644
    --- a/drivers/nvme/target/core.c
    +++ b/drivers/nvme/target/core.c
    @@ -555,7 +555,8 @@ int nvmet_ns_enable(struct nvmet_ns *ns)
    } else {
    struct nvmet_ns *old;

    - list_for_each_entry_rcu(old, &subsys->namespaces, dev_link) {
    + list_for_each_entry_rcu(old, &subsys->namespaces, dev_link,
    + lockdep_is_held(&subsys->lock)) {
    BUG_ON(ns->nsid == old->nsid);
    if (ns->nsid < old->nsid)
    break;
    @@ -1174,7 +1175,8 @@ static void nvmet_setup_p2p_ns_map(struct nvmet_ctrl *ctrl,

    ctrl->p2p_client = get_device(req->p2p_client);

    - list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link)
    + list_for_each_entry_rcu(ns, &ctrl->subsys->namespaces, dev_link,
    + lockdep_is_held(&ctrl->subsys->lock))
    nvmet_p2pmem_ns_add_p2p(ctrl, ns);
    }

    --
    2.20.1


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