diff options
Diffstat (limited to 'drivers/base/memory.c')
| -rw-r--r-- | drivers/base/memory.c | 44 |
1 files changed, 32 insertions, 12 deletions
diff --git a/drivers/base/memory.c b/drivers/base/memory.c index dbec3a05590a..2b09b68b9f78 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -21,6 +21,7 @@ #include <linux/mm.h> #include <linux/stat.h> #include <linux/slab.h> +#include <linux/xarray.h> #include <linux/atomic.h> #include <linux/uaccess.h> @@ -74,6 +75,13 @@ static struct bus_type memory_subsys = { .offline = memory_subsys_offline, }; +/* + * Memory blocks are cached in a local radix tree to avoid + * a costly linear search for the corresponding device on + * the subsystem bus. + */ +static DEFINE_XARRAY(memory_blocks); + static BLOCKING_NOTIFIER_HEAD(memory_chain); int register_memory_notifier(struct notifier_block *nb) @@ -489,22 +497,23 @@ int __weak arch_get_memory_phys_device(unsigned long start_pfn) return 0; } -/* A reference for the returned memory block device is acquired. */ +/* + * A reference for the returned memory block device is acquired. + * + * Called under device_hotplug_lock. + */ static struct memory_block *find_memory_block_by_id(unsigned long block_id) { - struct device *dev; + struct memory_block *mem; - dev = subsys_find_device_by_id(&memory_subsys, block_id, NULL); - return dev ? to_memory_block(dev) : NULL; + mem = xa_load(&memory_blocks, block_id); + if (mem) + get_device(&mem->dev); + return mem; } /* - * For now, we have a linear search to go find the appropriate - * memory_block corresponding to a particular phys_index. If - * this gets to be a real problem, we can always use a radix - * tree or something here. - * - * This could be made generic for all device subsystems. + * Called under device_hotplug_lock. */ struct memory_block *find_memory_block(struct mem_section *section) { @@ -548,9 +557,16 @@ int register_memory(struct memory_block *memory) memory->dev.offline = memory->state == MEM_OFFLINE; ret = device_register(&memory->dev); - if (ret) + if (ret) { put_device(&memory->dev); - + return ret; + } + ret = xa_err(xa_store(&memory_blocks, memory->dev.id, memory, + GFP_KERNEL)); + if (ret) { + put_device(&memory->dev); + device_unregister(&memory->dev); + } return ret; } @@ -604,6 +620,8 @@ static void unregister_memory(struct memory_block *memory) if (WARN_ON_ONCE(memory->dev.bus != &memory_subsys)) return; + WARN_ON(xa_erase(&memory_blocks, memory->dev.id) == NULL); + /* drop the ref. we got via find_memory_block() */ put_device(&memory->dev); device_unregister(&memory->dev); @@ -750,6 +768,8 @@ void __init memory_dev_init(void) * * In case func() returns an error, walking is aborted and the error is * returned. + * + * Called under device_hotplug_lock. */ int walk_memory_blocks(unsigned long start, unsigned long size, void *arg, walk_memory_blocks_func_t func) |