Re: [PATCH v2 2/2] nvmet-loop: Flush nvme_delete_wq when removing the port

From: Max Gurtovoy
Date: Fri Jul 05 2019 - 08:20:41 EST

On 7/4/2019 2:03 AM, Logan Gunthorpe wrote:
After calling nvme_loop_delete_ctrl(), the controllers will not
yet be deleted because nvme_delete_ctrl() only schedules work
to do the delete.

This means a race can occur if a port is removed but there
are still active controllers trying to access that memory.

To fix this, flush the nvme_delete_wq before returning from
nvme_loop_remove_port() so that any controllers that might
be in the process of being deleted won't access a freed port.

Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
drivers/nvme/target/loop.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/nvme/target/loop.c b/drivers/nvme/target/loop.c
index 9e211ad6bdd3..da9cd07461fb 100644
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c
@@ -654,6 +654,14 @@ static void nvme_loop_remove_port(struct nvmet_port *port)
+ /*
+ * Ensure any ctrls that are in the process of being
+ * deleted are in fact deleted before we return
+ * and free the port. This is to prevent active
+ * ctrls from using a port after it's freed.
+ */
+ flush_workqueue(nvme_delete_wq);
static const struct nvmet_fabrics_ops nvme_loop_ops = {

Looks good:

Reviewed-by: Max Gurtovoy <maxg@xxxxxxxxxxxx>