Once we have obtained a resource of a certain type from find_next_iomem_res(), it doesn't necessarily mean that the whole resource is usable, and we have cases where a child resource denotes an exclusion in the initial resource.
Provide a new walker that deals with this exact case, and calls a callback on each resource fragment that doesn't have a child. Signed-off-by: Marc Zyngier <[email protected]> --- include/linux/ioport.h | 4 +++ kernel/resource.c | 80 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 84 insertions(+) diff --git a/include/linux/ioport.h b/include/linux/ioport.h index 8359c50f9988..526314a42ad2 100644 --- a/include/linux/ioport.h +++ b/include/linux/ioport.h @@ -323,6 +323,10 @@ extern int walk_iomem_res_desc(unsigned long desc, unsigned long flags, u64 start, u64 end, void *arg, int (*func)(struct resource *, void *)); +extern int +walk_excluding_child_res(struct resource *res, void *arg, + int (*func)(struct resource *, void *)); + struct resource *devm_request_free_mem_region(struct device *dev, struct resource *base, unsigned long size); struct resource *request_free_mem_region(struct resource *base, diff --git a/kernel/resource.c b/kernel/resource.c index 311b8d2c9957..1d9b5f653938 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -318,6 +318,86 @@ int release_resource(struct resource *old) EXPORT_SYMBOL(release_resource); +/** + * walk_excluding_child_res - call a callback function on each fragment of + * a resource that do not have a child resource + * + * @res: the root resource containing the initial range + * @arg: function argument for the callback @func + * @func: callback function that is called for each qualifying resource area + * + * For a given resource, remove all the child resources and feed the + * resulting fragments to kexec_locate_mem_hole_callback(). + */ +int walk_excluding_child_res(struct resource *res, void *arg, + int (*func)(struct resource *, void *)) +{ + struct resource *tmp, cursor; + int ret = 0; + + cursor = *res; + + /* Use .child for the head of the list, .sibling for the tail */ + cursor.child = cursor.sibling = NULL; + + read_lock(&resource_lock); + + for (tmp = res->child; tmp; tmp = tmp->sibling) { + struct resource *new; + + if (cursor.start < tmp->start) { + new = kmalloc(sizeof(*new), GFP_KERNEL); + if (!new) + goto cleanup; + + *new = (struct resource) { + .start = cursor.start, + .end = tmp->start - 1, + .flags = res->flags, + .desc = res->desc, + .parent = res->parent, + }; + + if (!cursor.child) + cursor.child = new; + if (cursor.sibling) + cursor.sibling->sibling = new; + cursor.sibling = new; + } + + /* + * This may result in a resource with a negative size + * at the very end of the loop. + */ + cursor.start = tmp->end + 1; + } + + read_unlock(&resource_lock); + + /* + * At this stage, the list pointed to by cursor.child contains + * every non-reserved blocks, completed by 'cursor' which + * contains the potential last block (may be empty). + */ + for (tmp = cursor.child; tmp; tmp = tmp->sibling) { + ret = func(tmp, arg); + if (ret) + break; + } + + if (!ret && cursor.start <= cursor.end) + ret = func(&cursor, tmp); + +cleanup: + while (cursor.child) { + tmp = cursor.child; + cursor.child = cursor.child->sibling; + kfree(tmp); + } + + return ret; +} + /** * find_next_iomem_res - Finds the lowest iomem resource that covers part of * [@start..@end]. -- 2.30.2 _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
