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 <[email protected]>
---
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)
mutex_lock(&nvme_loop_ports_mutex);
list_del_init(&port->entry);
mutex_unlock(&nvme_loop_ports_mutex);
+
+ /*
+ * 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 = {
--
2.20.1
Reviewed-by: Sagi Grimberg <[email protected]>
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 <[email protected]>
> ---
> 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)
> mutex_lock(&nvme_loop_ports_mutex);
> list_del_init(&port->entry);
> mutex_unlock(&nvme_loop_ports_mutex);
> +
> + /*
> + * 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 <[email protected]>