> The lock ordering can cause potential deadlock. There are instances
> where hmem_resource_lock is taken after (node_chain).rwsem, and vice
> versa. Narrow the scope of hmem_resource_lock in hmem_register_resource()
> to avoid the circular locking dependency. The locking is only needed when
> hmem_active needs to be protected.
>
> Fixes: 7dab174e2e27 ("dax/hmem: Move hmem device registration to dax_hmem.ko")
> Signed-off-by: Dave Jiang <[email protected]>
One trivial thing...
> ---
> drivers/dax/hmem/device.c | 42 +++++++++++++++++++++++----------------
> 1 file changed, 25 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/dax/hmem/device.c b/drivers/dax/hmem/device.c
> index f9e1a76a04a9..ab5977d75d1f 100644
> --- a/drivers/dax/hmem/device.c
> +++ b/drivers/dax/hmem/device.c
> @@ -33,21 +33,37 @@ int walk_hmem_resources(struct device *host, walk_hmem_fn
> fn)
> }
> EXPORT_SYMBOL_GPL(walk_hmem_resources);
>
> -static void __hmem_register_resource(int target_nid, struct resource *res)
> +static struct resource *hmem_request_resource(int target_nid,
> + struct resource *res)
> {
> - struct platform_device *pdev;
> struct resource *new;
> - int rc;
>
> - new = __request_region(&hmem_active, res->start, resource_size(res), "",
> - 0);
> + guard(mutex)(&hmem_resource_lock);
> + new = __request_region(&hmem_active, res->start,
> + resource_size(res), "", 0);
Why the rewrap? Arguably it is slightly prettier but original was 80 chars
(I think) and making this change adds noise to the real code in this patch.
> if (!new) {
> pr_debug("hmem range %pr already active\n", res);
> - return;
> + return ERR_PTR(-ENOMEM);
> }
>
> new->desc = target_nid;
>
> + return new;
> +}
