| Message ID | 20201217234337.1983732-5-djrscally@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add functionality to ipu3-cio2 driver allowing software_node connections to sensors on platforms designed for Windows | expand |
Hi Daniel, Thank you for the patch. On Thu, Dec 17, 2020 at 11:43:29PM +0000, Daniel Scally wrote: > Registering software_nodes with the .parent member set to point to a > currently unregistered software_node has the potential for problems, > so enforce parent -> child ordering in arrays passed in to > software_node_register_nodes(). > > Software nodes that are children of another software node should be > unregistered before their parent. To allow easy unregistering of an array > of software_nodes ordered parent to child, reverse the order in which > software_node_unregister_nodes() unregisters software_nodes. > > Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Signed-off-by: Daniel Scally <djrscally@gmail.com> > --- > Changes in v2: > > - Squashed the patches that originally touched these separately > - Updated documentation > > drivers/base/swnode.c | 43 ++++++++++++++++++++++++++++++------------- > 1 file changed, 30 insertions(+), 13 deletions(-) > > diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c > index 615a0c93e116..cfd1faea48a7 100644 > --- a/drivers/base/swnode.c > +++ b/drivers/base/swnode.c > @@ -692,7 +692,10 @@ swnode_register(const struct software_node *node, struct swnode *parent, > * software_node_register_nodes - Register an array of software nodes > * @nodes: Zero terminated array of software nodes to be registered > * > - * Register multiple software nodes at once. > + * Register multiple software nodes at once. If any node in the array > + * has it's .parent pointer set, then it's parent **must** have been > + * registered before it is; either outside of this function or by > + * ordering the array such that parent comes before child. > */ > int software_node_register_nodes(const struct software_node *nodes) > { > @@ -700,33 +703,47 @@ int software_node_register_nodes(const struct software_node *nodes) > int i; > > for (i = 0; nodes[i].name; i++) { > - ret = software_node_register(&nodes[i]); > - if (ret) { > - software_node_unregister_nodes(nodes); > - return ret; > + const struct software_node *parent = nodes[i].parent; > + > + if (parent && !software_node_to_swnode(parent)) { > + ret = -EINVAL; > + goto err_unregister_nodes; > } > + > + ret = software_node_register(&nodes[i]); > + if (ret) > + goto err_unregister_nodes; > } > > return 0; > + > +err_unregister_nodes: > + software_node_unregister_nodes(nodes); > + return ret; > } > EXPORT_SYMBOL_GPL(software_node_register_nodes); > > /** > * software_node_unregister_nodes - Unregister an array of software nodes > - * @nodes: Zero terminated array of software nodes to be unregistered > + * @nodes: Zero terminated array of software nodes to be unregistered. Not sure if this is needed. > * > - * Unregister multiple software nodes at once. > + * Unregister multiple software nodes at once. If parent pointers are set up > + * in any of the software nodes then the array MUST be ordered such that I'd either replace **must** above with MUST, or use **must** here. I'm not sure if kerneldoc handles emphasis with **must**, if it does that seems a bit nicer to me, but it's really up to you. Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > + * parents come before their children. > * > - * NOTE: Be careful using this call if the nodes had parent pointers set up in > - * them before registering. If so, it is wiser to remove the nodes > - * individually, in the correct order (child before parent) instead of relying > - * on the sequential order of the list of nodes in the array. > + * NOTE: If you are uncertain whether the array is ordered such that > + * parents will be unregistered before their children, it is wiser to > + * remove the nodes individually, in the correct order (child before > + * parent). > */ > void software_node_unregister_nodes(const struct software_node *nodes) > { > - int i; > + unsigned int i = 0; > + > + while (nodes[i].name) > + i++; > > - for (i = 0; nodes[i].name; i++) > + while (i--) > software_node_unregister(&nodes[i]); > } > EXPORT_SYMBOL_GPL(software_node_unregister_nodes);
diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c index 615a0c93e116..cfd1faea48a7 100644 --- a/drivers/base/swnode.c +++ b/drivers/base/swnode.c @@ -692,7 +692,10 @@ swnode_register(const struct software_node *node, struct swnode *parent, * software_node_register_nodes - Register an array of software nodes * @nodes: Zero terminated array of software nodes to be registered * - * Register multiple software nodes at once. + * Register multiple software nodes at once. If any node in the array + * has it's .parent pointer set, then it's parent **must** have been + * registered before it is; either outside of this function or by + * ordering the array such that parent comes before child. */ int software_node_register_nodes(const struct software_node *nodes) { @@ -700,33 +703,47 @@ int software_node_register_nodes(const struct software_node *nodes) int i; for (i = 0; nodes[i].name; i++) { - ret = software_node_register(&nodes[i]); - if (ret) { - software_node_unregister_nodes(nodes); - return ret; + const struct software_node *parent = nodes[i].parent; + + if (parent && !software_node_to_swnode(parent)) { + ret = -EINVAL; + goto err_unregister_nodes; } + + ret = software_node_register(&nodes[i]); + if (ret) + goto err_unregister_nodes; } return 0; + +err_unregister_nodes: + software_node_unregister_nodes(nodes); + return ret; } EXPORT_SYMBOL_GPL(software_node_register_nodes); /** * software_node_unregister_nodes - Unregister an array of software nodes - * @nodes: Zero terminated array of software nodes to be unregistered + * @nodes: Zero terminated array of software nodes to be unregistered. * - * Unregister multiple software nodes at once. + * Unregister multiple software nodes at once. If parent pointers are set up + * in any of the software nodes then the array MUST be ordered such that + * parents come before their children. * - * NOTE: Be careful using this call if the nodes had parent pointers set up in - * them before registering. If so, it is wiser to remove the nodes - * individually, in the correct order (child before parent) instead of relying - * on the sequential order of the list of nodes in the array. + * NOTE: If you are uncertain whether the array is ordered such that + * parents will be unregistered before their children, it is wiser to + * remove the nodes individually, in the correct order (child before + * parent). */ void software_node_unregister_nodes(const struct software_node *nodes) { - int i; + unsigned int i = 0; + + while (nodes[i].name) + i++; - for (i = 0; nodes[i].name; i++) + while (i--) software_node_unregister(&nodes[i]); } EXPORT_SYMBOL_GPL(software_node_unregister_nodes);
Registering software_nodes with the .parent member set to point to a currently unregistered software_node has the potential for problems, so enforce parent -> child ordering in arrays passed in to software_node_register_nodes(). Software nodes that are children of another software node should be unregistered before their parent. To allow easy unregistering of an array of software_nodes ordered parent to child, reverse the order in which software_node_unregister_nodes() unregisters software_nodes. Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Daniel Scally <djrscally@gmail.com> --- Changes in v2: - Squashed the patches that originally touched these separately - Updated documentation drivers/base/swnode.c | 43 ++++++++++++++++++++++++++++++------------- 1 file changed, 30 insertions(+), 13 deletions(-)