diff options
Diffstat (limited to 'kernel/resource.c')
| -rw-r--r-- | kernel/resource.c | 198 |
1 files changed, 176 insertions, 22 deletions
diff --git a/kernel/resource.c b/kernel/resource.c index 73f35d4b30b..d7386986e10 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -21,6 +21,7 @@ #include <linux/seq_file.h> #include <linux/device.h> #include <linux/pfn.h> +#include <linux/mm.h> #include <asm/io.h> @@ -50,6 +51,14 @@ struct resource_constraint { static DEFINE_RWLOCK(resource_lock); +/* + * For memory hotplug, there is no way to free resource entries allocated + * by boot mem after the system is up. So for reusing the resource entry + * we need to remember the resource. + */ +static struct resource *bootmem_resource_free; +static DEFINE_SPINLOCK(bootmem_resource_lock); + static void *r_next(struct seq_file *m, void *v, loff_t *pos) { struct resource *p = v; @@ -151,6 +160,40 @@ __initcall(ioresources_init); #endif /* CONFIG_PROC_FS */ +static void free_resource(struct resource *res) +{ + if (!res) + return; + + if (!PageSlab(virt_to_head_page(res))) { + spin_lock(&bootmem_resource_lock); + res->sibling = bootmem_resource_free; + bootmem_resource_free = res; + spin_unlock(&bootmem_resource_lock); + } else { + kfree(res); + } +} + +static struct resource *alloc_resource(gfp_t flags) +{ + struct resource *res = NULL; + + spin_lock(&bootmem_resource_lock); + if (bootmem_resource_free) { + res = bootmem_resource_free; + bootmem_resource_free = res->sibling; + } + spin_unlock(&bootmem_resource_lock); + + if (res) + memset(res, 0, sizeof(struct resource)); + else + res = kzalloc(sizeof(struct resource), flags); + + return res; +} + /* Return the conflict entry if you can't request it */ static struct resource * __request_resource(struct resource *root, struct resource *new) { @@ -706,24 +749,13 @@ void insert_resource_expand_to_fit(struct resource *root, struct resource *new) write_unlock(&resource_lock); } -/** - * adjust_resource - modify a resource's start and size - * @res: resource to modify - * @start: new start value - * @size: new size - * - * Given an existing resource, change its start and size to match the - * arguments. Returns 0 on success, -EBUSY if it can't fit. - * Existing children of the resource are assumed to be immutable. - */ -int adjust_resource(struct resource *res, resource_size_t start, resource_size_t size) +static int __adjust_resource(struct resource *res, resource_size_t start, + resource_size_t size) { struct resource *tmp, *parent = res->parent; resource_size_t end = start + size - 1; int result = -EBUSY; - write_lock(&resource_lock); - if (!parent) goto skip; @@ -751,6 +783,26 @@ skip: result = 0; out: + return result; +} + +/** + * adjust_resource - modify a resource's start and size + * @res: resource to modify + * @start: new start value + * @size: new size + * + * Given an existing resource, change its start and size to match the + * arguments. Returns 0 on success, -EBUSY if it can't fit. + * Existing children of the resource are assumed to be immutable. + */ +int adjust_resource(struct resource *res, resource_size_t start, + resource_size_t size) +{ + int result; + + write_lock(&resource_lock); + result = __adjust_resource(res, start, size); write_unlock(&resource_lock); return result; } @@ -762,7 +814,7 @@ static void __init __reserve_region_with_split(struct resource *root, { struct resource *parent = root; struct resource *conflict; - struct resource *res = kzalloc(sizeof(*res), GFP_ATOMIC); + struct resource *res = alloc_resource(GFP_ATOMIC); struct resource *next_res = NULL; if (!res) @@ -787,7 +839,7 @@ static void __init __reserve_region_with_split(struct resource *root, /* conflict covered whole area */ if (conflict->start <= res->start && conflict->end >= res->end) { - kfree(res); + free_resource(res); WARN_ON(next_res); break; } @@ -797,10 +849,9 @@ static void __init __reserve_region_with_split(struct resource *root, end = res->end; res->end = conflict->start - 1; if (conflict->end < end) { - next_res = kzalloc(sizeof(*next_res), - GFP_ATOMIC); + next_res = alloc_resource(GFP_ATOMIC); if (!next_res) { - kfree(res); + free_resource(res); break; } next_res->name = name; @@ -890,7 +941,7 @@ struct resource * __request_region(struct resource *parent, const char *name, int flags) { DECLARE_WAITQUEUE(wait, current); - struct resource *res = kzalloc(sizeof(*res), GFP_KERNEL); + struct resource *res = alloc_resource(GFP_KERNEL); if (!res) return NULL; @@ -924,7 +975,7 @@ struct resource * __request_region(struct resource *parent, continue; } /* Uhhuh, that didn't work out.. */ - kfree(res); + free_resource(res); res = NULL; break; } @@ -958,7 +1009,7 @@ int __check_region(struct resource *parent, resource_size_t start, return -EBUSY; release_resource(res); - kfree(res); + free_resource(res); return 0; } EXPORT_SYMBOL(__check_region); @@ -998,7 +1049,7 @@ void __release_region(struct resource *parent, resource_size_t start, write_unlock(&resource_lock); if (res->flags & IORESOURCE_MUXED) wake_up(&muxed_resource_wait); - kfree(res); + free_resource(res); return; } p = &res->sibling; @@ -1012,6 +1063,109 @@ void __release_region(struct resource *parent, resource_size_t start, } EXPORT_SYMBOL(__release_region); +#ifdef CONFIG_MEMORY_HOTREMOVE +/** + * release_mem_region_adjustable - release a previously reserved memory region + * @parent: parent resource descriptor + * @start: resource start address + * @size: resource region size + * + * This interface is intended for memory hot-delete. The requested region + * is released from a currently busy memory resource. The requested region + * must either match exactly or fit into a single busy resource entry. In + * the latter case, the remaining resource is adjusted accordingly. + * Existing children of the busy memory resource must be immutable in the + * request. + * + * Note: + * - Additional release conditions, such as overlapping region, can be + * supported after they are confirmed as valid cases. + * - When a busy memory resource gets split into two entries, the code + * assumes that all children remain in the lower address entry for + * simplicity. Enhance this logic when necessary. + */ +int release_mem_region_adjustable(struct resource *parent, + resource_size_t start, resource_size_t size) +{ + struct resource **p; + struct resource *res; + struct resource *new_res; + resource_size_t end; + int ret = -EINVAL; + + end = start + size - 1; + if ((start < parent->start) || (end > parent->end)) + return ret; + + /* The alloc_resource() result gets checked later */ + new_res = alloc_resource(GFP_KERNEL); + + p = &parent->child; + write_lock(&resource_lock); + + while ((res = *p)) { + if (res->start >= end) + break; + + /* look for the next resource if it does not fit into */ + if (res->start > start || res->end < end) { + p = &res->sibling; + continue; + } + + if (!(res->flags & IORESOURCE_MEM)) + break; + + if (!(res->flags & IORESOURCE_BUSY)) { + p = &res->child; + continue; + } + + /* found the target resource; let's adjust accordingly */ + if (res->start == start && res->end == end) { + /* free the whole entry */ + *p = res->sibling; + free_resource(res); + ret = 0; + } else if (res->start == start && res->end != end) { + /* adjust the start */ + ret = __adjust_resource(res, end + 1, + res->end - end); + } else if (res->start != start && res->end == end) { + /* adjust the end */ + ret = __adjust_resource(res, res->start, + start - res->start); + } else { + /* split into two entries */ + if (!new_res) { + ret = -ENOMEM; + break; + } + new_res->name = res->name; + new_res->start = end + 1; + new_res->end = res->end; + new_res->flags = res->flags; + new_res->parent = res->parent; + new_res->sibling = res->sibling; + new_res->child = NULL; + + ret = __adjust_resource(res, res->start, + start - res->start); + if (ret) + break; + res->sibling = new_res; + new_res = NULL; + } + + break; + } + + write_unlock(&resource_lock); + free_resource(new_res); + return ret; +} +#endif /* CONFIG_MEMORY_HOTREMOVE */ + /* * Managed region resource */ |