On Thu, Sep 04, 2008 at 04:05:22AM -0400, Oren Laadan wrote: > > Infrastructure to handle objects that may be shared and referenced by > multiple tasks or other objects, e..g open files, memory address space > etc. > > The state of shared objects is saved once. On the first encounter, the > state is dumped and the object is assigned a unique identifier and also > stored in a hash table (indexed by its physical kenrel address). From > then on the object will be found in the hash and only its identifier is > saved. > > On restart the identifier is looked up in the hash table; if not found > then the state is read, the object is created, and added to the hash > table (this time indexed by its identifier). Otherwise, the object in > the hash table is used. >
[...]
> diff --git a/checkpoint/objhash.c b/checkpoint/objhash.c
> new file mode 100644
> index 0000000..442b08c
> --- /dev/null
> +++ b/checkpoint/objhash.c
> @@ -0,0 +1,205 @@
> +/*
> + * Checkpoint-restart - object hash infrastructure to manage shared objects
> + *
> + * Copyright (C) 2008 Oren Laadan
> + *
> + * This file is subject to the terms and conditions of the GNU General
> Public
> + * License. See the file COPYING in the main directory of the Linux
> + * distribution for more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/file.h>
> +#include <linux/hash.h>
> +#include <linux/ckpt.h>
> +
> +struct cr_objref {
> + int objref;
> + void *ptr;
> + unsigned short type;
> + unsigned short flags;
> + struct hlist_node hash;
> +};
> +
> +struct cr_objhash {
> + struct hlist_head *head;
> + int objref_index;
> +};
> +
> +#define CR_OBJHASH_NBITS 10
> +#define CR_OBJHASH_TOTAL (1UL << CR_OBJHASH_NBITS - 1)
Why -1? This makes a total number of 512 entries, which will break below with
hashes in range 0..1023.
> +
> +static void cr_obj_ref_drop(struct cr_objref *obj)
> +{
> + switch (obj->type) {
> + case CR_OBJ_FILE:
> + fput((struct file *) obj->ptr);
> + break;
> + default:
> + BUG();
> + }
> +}
> +
> +static void cr_obj_ref_grab(struct cr_objref *obj)
> +{
> + switch (obj->type) {
> + case CR_OBJ_FILE:
> + get_file((struct file *) obj->ptr);
> + break;
> + default:
> + BUG();
> + }
> +}
> +
> +static void cr_objhash_clear(struct cr_objhash *objhash)
> +{
> + struct hlist_head *h = objhash->head;
> + struct hlist_node *n, *t;
> + struct cr_objref *obj;
> + int i;
> +
> + for (i = 0; i < CR_OBJHASH_TOTAL; i++) {
> + hlist_for_each_entry_safe(obj, n, t, &h[i], hash) {
> + cr_obj_ref_drop(obj);
> + kfree(obj);
> + }
> + }
> +}
> +
> +void cr_objhash_free(struct cr_ctx *ctx)
> +{
> + struct cr_objhash *objhash = ctx->objhash;
> +
> + if (objhash) {
> + cr_objhash_clear(objhash);
> + kfree(objhash->head);
> + kfree(ctx->objhash);
> + ctx->objhash = NULL;
> + }
> +}
> +
> +int cr_objhash_alloc(struct cr_ctx *ctx)
> +{
> + struct cr_objhash *objhash;
> + struct hlist_head *head;
> +
> + objhash = kzalloc(sizeof(*objhash), GFP_KERNEL);
> + if (!objhash)
> + return -ENOMEM;
> + head = kzalloc(CR_OBJHASH_TOTAL * sizeof(*head), GFP_KERNEL);
512 entries allocated
> + if (!head) {
> + kfree(objhash);
> + return -ENOMEM;
> + }
> +
> + objhash->head = head;
> + objhash->objref_index = 1;
> +
> + ctx->objhash = objhash;
> + return 0;
> +}
> +
> +static struct cr_objref *cr_obj_find_by_ptr(struct cr_ctx *ctx, void *ptr)
> +{
> + struct hlist_head *h;
> + struct hlist_node *n;
> + struct cr_objref *obj;
> +
> + h = &ctx->objhash->head[hash_ptr(ptr, CR_OBJHASH_NBITS)];
access to entries 0..1023
Louis
--
Dr Louis Rilling Kerlabs
Skype: louis.rilling Batiment Germanium
Phone: (+33|0) 6 80 89 08 23 80 avenue des Buttes de Coesmes
http://www.kerlabs.com/ 35700 Rennes
signature.asc
Description: Digital signature
_______________________________________________ Containers mailing list [EMAIL PROTECTED] https://lists.linux-foundation.org/mailman/listinfo/containers
_______________________________________________ Devel mailing list Devel@openvz.org https://openvz.org/mailman/listinfo/devel
