lib/objpool.c

Source file repositories/reference/linux-study-clean/lib/objpool.c

File Facts

System
Linux kernel
Corpus path
lib/objpool.c
Extension
.c
Size
5099 bytes
Lines
204
Domain
Kernel Services
Bucket
lib
Inferred role
Kernel Services: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Shared kernel service surface used by multiple subsystems, including helpers, cryptography, virtualization support, and async I/O infrastructure.

Dependency Surface

Detected Declarations

Annotated Snippet

if (objinit) {
			int rc = objinit(obj, context);
			if (rc)
				return rc;
		}
		slot->entries[slot->tail & slot->mask] = obj;
		obj = obj + pool->obj_size;
		slot->tail++;
		slot->last = slot->tail;
		pool->nr_objs++;
	}

	return 0;
}

/* allocate and initialize percpu slots */
static int
objpool_init_percpu_slots(struct objpool_head *pool, int nr_objs,
			  void *context, objpool_init_obj_cb objinit)
{
	int i, cpu_count = 0;

	for (i = 0; i < nr_cpu_ids; i++) {

		struct objpool_slot *slot;
		int nodes, size, rc;

		/* skip the cpu node which could never be present */
		if (!cpu_possible(i))
			continue;

		/* compute how many objects to be allocated with this slot */
		nodes = nr_objs / pool->nr_possible_cpus;
		if (cpu_count < (nr_objs % pool->nr_possible_cpus))
			nodes++;
		cpu_count++;

		size = struct_size(slot, entries, pool->capacity) +
			pool->obj_size * nodes;

		/*
		 * here we allocate percpu-slot & objs together in a single
		 * allocation to make it more compact, taking advantage of
		 * warm caches and TLB hits. in default vmalloc is used to
		 * reduce the pressure of kernel slab system. as we know,
		 * mimimal size of vmalloc is one page since vmalloc would
		 * always align the requested size to page size.
		 * but if vmalloc fails or it is not available (e.g. GFP_ATOMIC)
		 * allocate percpu slot with kmalloc.
		 */
		slot = NULL;

		if ((pool->gfp & (GFP_ATOMIC | GFP_KERNEL)) != GFP_ATOMIC)
			slot = __vmalloc_node(size, sizeof(void *), pool->gfp,
				cpu_to_node(i), __builtin_return_address(0));

		if (!slot) {
			slot = kmalloc_node(size, pool->gfp, cpu_to_node(i));
			if (!slot)
				return -ENOMEM;
		}
		memset(slot, 0, size);
		pool->cpu_slots[i] = slot;

		/* initialize the objpool_slot of cpu node i */
		rc = objpool_init_percpu_slot(pool, slot, nodes, context, objinit);
		if (rc)
			return rc;
	}

	return 0;
}

/* cleanup all percpu slots of the object pool */
static void objpool_fini_percpu_slots(struct objpool_head *pool)
{
	int i;

	if (!pool->cpu_slots)
		return;

	for (i = 0; i < nr_cpu_ids; i++)
		kvfree(pool->cpu_slots[i]);
	kfree(pool->cpu_slots);
}

/* initialize object pool and pre-allocate objects */
int objpool_init(struct objpool_head *pool, int nr_objs, int object_size,
		gfp_t gfp, void *context, objpool_init_obj_cb objinit,
		objpool_fini_cb release)

Annotation

Implementation Notes