Don't lock a parent device unless it is needed in device_shutdown. This
is in preparation for making device shutdown asynchronous, when it will
be needed to allow children of a common parent to shut down
simultaneously.

Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: David Jeffery <djeffery@redhat.com>
---
 drivers/base/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 2b4c0624b704..03edf7a7ec37 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -4815,7 +4815,7 @@ void device_shutdown(void)
 		spin_unlock(&devices_kset->list_lock);
 
 		/* hold lock to avoid race with probe/release */
-		if (parent)
+		if (parent && dev->bus && dev->bus->need_parent_lock)
 			device_lock(parent);
 		device_lock(dev);
 
@@ -4839,7 +4839,7 @@ void device_shutdown(void)
 		}
 
 		device_unlock(dev);
-		if (parent)
+		if (parent && dev->bus && dev->bus->need_parent_lock)
 			device_unlock(parent);
 
 		put_device(dev);
-- 
2.39.3

On Wed, Jun 26, 2024 at 02:46:47PM -0500, Stuart Hayes wrote:
> Don't lock a parent device unless it is needed in device_shutdown. This
> is in preparation for making device shutdown asynchronous, when it will
> be needed to allow children of a common parent to shut down
> simultaneously.

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

.. but I guess this means async shutdown won't work well for busses
that set this flag (just usb currently)?

On Thu, Jun 27, 2024 at 07:51:21AM +0200, Christoph Hellwig wrote:
> On Wed, Jun 26, 2024 at 02:46:47PM -0500, Stuart Hayes wrote:
> > Don't lock a parent device unless it is needed in device_shutdown. This
> > is in preparation for making device shutdown asynchronous, when it will
> > be needed to allow children of a common parent to shut down
> > simultaneously.
> 
> Looks good:
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> 
> .. but I guess this means async shutdown won't work well for busses
> that set this flag (just usb currently)?

USB can't do async shutdown due to the tree topology requirements here
so hopefully this should be ok.

thanks,

greg k-h