[PATCH 7.1 227/271] dibs: initialise dibs->lock in dibs_dev_alloc()

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hidayath Khan <[email protected]>

commit c27e360545373b7aee9862a5beef3b9fb3df0c25 upstream.

dibs->lock is initialised by dibs_dev_add(), but a dibs device can
already take interrupts before that call: ism_probe() runs
ism_dev_init(), and hence request_irq(), before it calls
dibs_dev_add(). No client can have registered a dmb at that point, so
no dmb interrupt can occur, but a GID event interrupt can, and
ism_handle_irq() takes dibs->lock unconditionally on entry, before it
inspects anything else.

Initialise the lock in dibs_dev_alloc() instead, so that it is valid as
soon as a driver can publish the device to its interrupt handler.

Fixes: cc21191b584c ("dibs: Move data path to dibs layer")
Cc: [email protected]
Reviewed-by: Alexandra Winter <[email protected]>
Signed-off-by: Hidayath Khan <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/dibs/dibs_main.c |    2 +-
 include/linux/dibs.h     |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/dibs/dibs_main.c
+++ b/drivers/dibs/dibs_main.c
@@ -139,6 +139,7 @@ struct dibs_dev *dibs_dev_alloc(void)
 	dibs = kzalloc_obj(*dibs);
 	if (!dibs)
 		return dibs;
+	spin_lock_init(&dibs->lock);
 	dibs->dev.release = dibs_dev_release;
 	dibs->dev.class = &dibs_class;
 	device_initialize(&dibs->dev);
@@ -187,7 +188,6 @@ int dibs_dev_add(struct dibs_dev *dibs)
 	int i, ret;
 
 	max_dmbs = dibs->ops->max_dmbs();
-	spin_lock_init(&dibs->lock);
 	dibs->dmb_clientid_arr = kzalloc(max_dmbs, GFP_KERNEL);
 	if (!dibs->dmb_clientid_arr)
 		return -ENOMEM;
--- a/include/linux/dibs.h
+++ b/include/linux/dibs.h
@@ -439,7 +439,7 @@ static inline void *dibs_get_priv(struct
 /**
  * dibs_dev_alloc() - allocate and reference device structure
  *
- * The following fields will be valid upon successful return: dev
+ * The following fields will be valid upon successful return: dev, lock
  * NOTE: Use put_device(dibs_get_dev(@dibs)) to give up your reference instead
  * of freeing @dibs @dev directly once you have successfully called this
  * function.