From 1da11f822042eb6ef4b6064dc048f157a7852529 Mon Sep 17 00:00:00 2001 From: Marco Pagani Date: Fri, 22 Mar 2024 18:18:37 +0100 Subject: fpga: bridge: add owner module and take its refcount The current implementation of the fpga bridge assumes that the low-level module registers a driver for the parent device and uses its owner pointer to take the module's refcount. This approach is problematic since it can lead to a null pointer dereference while attempting to get the bridge if the parent device does not have a driver. To address this problem, add a module owner pointer to the fpga_bridge struct and use it to take the module's refcount. Modify the function for registering a bridge to take an additional owner module parameter and rename it to avoid conflicts. Use the old function name for a helper macro that automatically sets the module that registers the bridge as the owner. This ensures compatibility with existing low-level control modules and reduces the chances of registering a bridge without setting the owner. Also, update the documentation to keep it consistent with the new interface for registering an fpga bridge. Other changes: opportunistically move put_device() from __fpga_bridge_get() to fpga_bridge_get() and of_fpga_bridge_get() to improve code clarity since the bridge device is taken in these functions. Fixes: 21aeda950c5f ("fpga: add fpga bridge framework") Suggested-by: Greg Kroah-Hartman Suggested-by: Xu Yilun Reviewed-by: Russ Weight Signed-off-by: Marco Pagani Acked-by: Xu Yilun Link: https://lore.kernel.org/r/20240322171839.233864-1-marpagan@redhat.com Signed-off-by: Xu Yilun --- include/linux/fpga/fpga-bridge.h | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'include/linux/fpga') diff --git a/include/linux/fpga/fpga-bridge.h b/include/linux/fpga/fpga-bridge.h index 223da48a6d18..94c4edd047e5 100644 --- a/include/linux/fpga/fpga-bridge.h +++ b/include/linux/fpga/fpga-bridge.h @@ -45,6 +45,7 @@ struct fpga_bridge_info { * @dev: FPGA bridge device * @mutex: enforces exclusive reference to bridge * @br_ops: pointer to struct of FPGA bridge ops + * @br_ops_owner: module containing the br_ops * @info: fpga image specific information * @node: FPGA bridge list node * @priv: low level driver private date @@ -54,6 +55,7 @@ struct fpga_bridge { struct device dev; struct mutex mutex; /* for exclusive reference to bridge */ const struct fpga_bridge_ops *br_ops; + struct module *br_ops_owner; struct fpga_image_info *info; struct list_head node; void *priv; @@ -79,10 +81,12 @@ int of_fpga_bridge_get_to_list(struct device_node *np, struct fpga_image_info *info, struct list_head *bridge_list); +#define fpga_bridge_register(parent, name, br_ops, priv) \ + __fpga_bridge_register(parent, name, br_ops, priv, THIS_MODULE) struct fpga_bridge * -fpga_bridge_register(struct device *parent, const char *name, - const struct fpga_bridge_ops *br_ops, - void *priv); +__fpga_bridge_register(struct device *parent, const char *name, + const struct fpga_bridge_ops *br_ops, void *priv, + struct module *owner); void fpga_bridge_unregister(struct fpga_bridge *br); #endif /* _LINUX_FPGA_BRIDGE_H */ -- cgit v1.2.3-73-gaa49b