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    Subject[PATCH 27/38] C/R: checkpoint/restore struct uts_namespace
    Date
    The simplest thing.

    Note, no locking is done, because we know:
    a) tasks are frozen and thus can't change it
    b) number of collected references is correct, so nobody else
    is using uts_namespace and thus can't change it under dump

    If live checkpointing will be done, code will be changed
    to something like:

    if (ctx->dump_live)
    down_read(&uts_sem);
    ...
    if (ctx->dump_live)
    up_read(&uts_sem);

    Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
    ---
    include/linux/kstate-image.h | 14 +++++
    include/linux/kstate.h | 5 ++
    kernel/kstate/cpt-sys.c | 6 ++
    kernel/kstate/kstate-context.c | 6 ++
    kernel/kstate/kstate-object.c | 4 ++
    kernel/nsproxy.c | 33 +++++++++++--
    kernel/utsname.c | 106 ++++++++++++++++++++++++++++++++++++++++
    7 files changed, 170 insertions(+), 4 deletions(-)
    delete mode 100644 kernel/kstate/kstate-nsproxy.c
    create mode 100644 kernel/kstate/kstate-uts_ns.c

    diff --git a/include/linux/kstate-image.h b/include/linux/kstate-image.h
    index b8263c8..2eef50b 100644
    --- a/include/linux/kstate-image.h
    +++ b/include/linux/kstate-image.h
    @@ -44,6 +44,7 @@ struct kstate_image_header {
    #define KSTATE_OBJ_VMA 4
    #define KSTATE_OBJ_PAGE 5
    #define KSTATE_OBJ_NSPROXY 6
    +#define KSTATE_OBJ_UTS_NS 7

    struct kstate_object_header {
    __u32 obj_type;
    @@ -208,5 +209,18 @@ struct kstate_image_file {

    struct kstate_image_nsproxy {
    struct kstate_object_header hdr;
    +
    + kstate_ref_t ref_uts_ns;
    +} __packed;
    +
    +struct kstate_image_uts_ns {
    + struct kstate_object_header hdr;
    +
    + __u8 sysname[64];
    + __u8 nodename[64];
    + __u8 release[64];
    + __u8 version[64];
    + __u8 machine[64];
    + __u8 domainname[64];
    } __packed;
    #endif
    diff --git a/include/linux/kstate.h b/include/linux/kstate.h
    index bd5c9f1..dba4803 100644
    --- a/include/linux/kstate.h
    +++ b/include/linux/kstate.h
    @@ -25,6 +25,7 @@ enum kstate_context_obj_type {
    KSTATE_CTX_MM_STRUCT,
    KSTATE_CTX_NSPROXY,
    KSTATE_CTX_TASK_STRUCT,
    + KSTATE_CTX_UTS_NS,
    NR_KSTATE_CTX_TYPES
    };

    @@ -72,6 +73,10 @@ int kstate_collect_all_nsproxy(struct kstate_context *ctx);
    int kstate_dump_all_nsproxy(struct kstate_context *ctx);
    int kstate_restore_nsproxy(struct kstate_context *ctx, kstate_ref_t *ref);

    +int kstate_collect_all_uts_ns(struct kstate_context *ctx);
    +int kstate_dump_all_uts_ns(struct kstate_context *ctx);
    +int kstate_restore_uts_ns(struct kstate_context *ctx, kstate_ref_t *ref);
    +
    #if defined(CONFIG_X86_32) || defined(CONFIG_X86_64)
    extern const __u32 kstate_kernel_arch;
    int kstate_arch_check_image_header(struct kstate_image_header *i);
    diff --git a/kernel/kstate/cpt-sys.c b/kernel/kstate/cpt-sys.c
    index 1d5e79d..7d4681a 100644
    --- a/kernel/kstate/cpt-sys.c
    +++ b/kernel/kstate/cpt-sys.c
    @@ -68,6 +68,9 @@ static int kstate_collect(struct kstate_context *ctx)
    rv = kstate_collect_all_nsproxy(ctx);
    if (rv < 0)
    return rv;
    + rv = kstate_collect_all_uts_ns(ctx);
    + if (rv < 0)
    + return rv;
    rv = kstate_collect_all_mm_struct(ctx);
    if (rv < 0)
    return rv;
    @@ -130,6 +133,9 @@ static int kstate_dump(struct kstate_context *ctx)
    rv = kstate_dump_all_mm_struct(ctx);
    if (rv < 0)
    return rv;
    + rv = kstate_dump_all_uts_ns(ctx);
    + if (rv < 0)
    + return rv;
    rv = kstate_dump_all_nsproxy(ctx);
    if (rv < 0)
    return rv;
    diff --git a/kernel/kstate/kstate-context.c b/kernel/kstate/kstate-context.c
    index 8c728f5..98dc0c0 100644
    --- a/kernel/kstate/kstate-context.c
    +++ b/kernel/kstate/kstate-context.c
    @@ -4,6 +4,7 @@
    #include <linux/nsproxy.h>
    #include <linux/sched.h>
    #include <linux/slab.h>
    +#include <linux/utsname.h>

    #include <linux/kstate.h>

    @@ -51,5 +52,10 @@ void kstate_context_destroy(struct kstate_context *ctx)
    list_del(&obj->o_list);
    kfree(obj);
    }
    + for_each_kstate_object_safe(ctx, obj, tmp, KSTATE_CTX_UTS_NS) {
    + put_uts_ns((struct uts_namespace *)obj->o_obj);
    + list_del(&obj->o_list);
    + kfree(obj);
    + }
    kfree(ctx);
    }
    diff --git a/kernel/kstate/kstate-nsproxy.c b/kernel/kstate/kstate-nsproxy.c
    deleted file mode 100644
    index e69de29..0000000
    diff --git a/kernel/kstate/kstate-object.c b/kernel/kstate/kstate-object.c
    index 078bd36..aeadd95 100644
    --- a/kernel/kstate/kstate-object.c
    +++ b/kernel/kstate/kstate-object.c
    @@ -4,6 +4,7 @@
    #include <linux/nsproxy.h>
    #include <linux/sched.h>
    #include <linux/slab.h>
    +#include <linux/utsname.h>

    #include <linux/kstate.h>
    #include <linux/kstate-image.h>
    @@ -42,6 +43,9 @@ int kstate_collect_object(struct kstate_context *ctx, void *p, enum kstate_conte
    case KSTATE_CTX_TASK_STRUCT:
    get_task_struct((struct task_struct *)obj->o_obj);
    break;
    + case KSTATE_CTX_UTS_NS:
    + get_uts_ns((struct uts_namespace *)obj->o_obj);
    + break;
    default:
    BUG();
    }
    diff --git a/kernel/kstate/kstate-uts_ns.c b/kernel/kstate/kstate-uts_ns.c
    new file mode 100644
    index 0000000..e69de29
    diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
    index b7ccd68..b2a7ed3 100644
    --- a/kernel/nsproxy.c
    +++ b/kernel/nsproxy.c
    @@ -271,12 +271,16 @@ static int dump_nsproxy(struct kstate_context *ctx, struct kstate_object *obj)
    {
    struct nsproxy *nsproxy = obj->o_obj;
    struct kstate_image_nsproxy *i;
    + struct kstate_object *tmp;
    int rv;

    i = kstate_prepare_image(KSTATE_OBJ_NSPROXY, sizeof(*i));
    if (!i)
    return -ENOMEM;

    + tmp = find_kstate_obj_by_ptr(ctx, nsproxy->uts_ns, KSTATE_CTX_UTS_NS);
    + i->ref_uts_ns = tmp->o_ref;
    +
    rv = kstate_write_image(ctx, i, sizeof(*i), obj);
    kfree(i);
    pr_debug("dump nsproxy %p: ref {%llu, %u}, rv %d\n", nsproxy, (unsigned long long)obj->o_ref.pos, obj->o_ref.id, rv);
    @@ -296,11 +300,30 @@ int kstate_dump_all_nsproxy(struct kstate_context *ctx)
    return 0;
    }

    +static int restore_uts_ns(struct kstate_context *ctx, kstate_ref_t *ref, struct nsproxy *nsproxy)
    +{
    + struct uts_namespace *uts_ns;
    + struct kstate_object *tmp;
    + int rv;
    +
    + tmp = find_kstate_obj_by_ref(ctx, ref, KSTATE_CTX_UTS_NS);
    + if (!tmp) {
    + rv = kstate_restore_uts_ns(ctx, ref);
    + if (rv < 0)
    + return rv;
    + tmp = find_kstate_obj_by_ref(ctx, ref, KSTATE_CTX_UTS_NS);
    + }
    + uts_ns = tmp->o_obj;
    +
    + get_uts_ns(uts_ns);
    + nsproxy->uts_ns = uts_ns;
    + return 0;
    +}
    +
    int kstate_restore_nsproxy(struct kstate_context *ctx, kstate_ref_t *ref)
    {
    struct kstate_image_nsproxy *i;
    struct nsproxy *nsproxy;
    - struct uts_namespace *uts_ns;
    #ifdef CONFIG_IPC_NS
    struct ipc_namespace *ipc_ns;
    #endif
    @@ -321,9 +344,9 @@ int kstate_restore_nsproxy(struct kstate_context *ctx, kstate_ref_t *ref)
    goto out_free_image;
    }

    - uts_ns = ctx->init_tsk->nsproxy->uts_ns;
    - get_uts_ns(uts_ns);
    - nsproxy->uts_ns = uts_ns;
    + rv = restore_uts_ns(ctx, &i->ref_uts_ns, nsproxy);
    + if (rv < 0)
    + goto out_uts_ns;

    #ifdef CONFIG_IPC_NS
    ipc_ns = ctx->init_tsk->nsproxy->ipc_ns;
    @@ -349,6 +372,8 @@ int kstate_restore_nsproxy(struct kstate_context *ctx, kstate_ref_t *ref)
    pr_debug("restore nsproxy %p, ref {%llu, %u}, rv %d\n", nsproxy, (unsigned long long)ref->pos, ref->id, rv);
    return rv;

    +out_uts_ns:
    + kmem_cache_free(nsproxy_cachep, nsproxy);
    out_free_image:
    kfree(i);
    pr_debug("%s: return %d, ref {%llu, %u}\n", __func__, rv, (unsigned long long)ref->pos, ref->id);
    diff --git a/kernel/utsname.c b/kernel/utsname.c
    index 8a82b4b..5b25e8d 100644
    --- a/kernel/utsname.c
    +++ b/kernel/utsname.c
    @@ -1,5 +1,6 @@
    /*
    * Copyright (C) 2004 IBM Corporation
    + * Copyright (C) 2009 Parallels Holdings, Ltd.
    *
    * Author: Serge Hallyn <serue@us.ibm.com>
    *
    @@ -73,3 +74,108 @@ void free_uts_ns(struct kref *kref)
    ns = container_of(kref, struct uts_namespace, kref);
    kfree(ns);
    }
    +
    +#ifdef CONFIG_CHECKPOINT
    +#include <linux/kstate.h>
    +#include <linux/kstate-image.h>
    +
    +static int collect_uts_ns(struct kstate_context *ctx, struct uts_namespace *uts_ns)
    +{
    + int rv;
    +
    + rv = kstate_collect_object(ctx, uts_ns, KSTATE_CTX_UTS_NS);
    + pr_debug("collect uts_ns %p: rv %d\n", uts_ns, rv);
    + return rv;
    +}
    +
    +int kstate_collect_all_uts_ns(struct kstate_context *ctx)
    +{
    + struct kstate_object *obj;
    + int rv;
    +
    + for_each_kstate_object(ctx, obj, KSTATE_CTX_NSPROXY) {
    + struct nsproxy *nsproxy = obj->o_obj;
    +
    + rv = collect_uts_ns(ctx, nsproxy->uts_ns);
    + if (rv < 0)
    + return rv;
    + }
    + for_each_kstate_object(ctx, obj, KSTATE_CTX_UTS_NS) {
    + struct uts_namespace *uts_ns = obj->o_obj;
    + unsigned int cnt = atomic_read(&uts_ns->kref.refcount);
    +
    + if (obj->o_count + 1 != cnt) {
    + pr_err("uts_ns %p has external references %lu:%u\n", uts_ns, obj->o_count, cnt);
    + return -EINVAL;
    + }
    + }
    + return 0;
    +}
    +
    +static int dump_uts_ns(struct kstate_context *ctx, struct kstate_object *obj)
    +{
    + struct uts_namespace *uts_ns = obj->o_obj;
    + struct kstate_image_uts_ns *i;
    + int rv;
    +
    + i = kstate_prepare_image(KSTATE_OBJ_UTS_NS, sizeof(*i));
    + if (!i)
    + return -ENOMEM;
    +
    + strncpy(i->sysname, (const char *)uts_ns->name.sysname, 64);
    + strncpy(i->nodename, (const char *)uts_ns->name.nodename, 64);
    + strncpy(i->release, (const char *)uts_ns->name.release, 64);
    + strncpy(i->version, (const char *)uts_ns->name.version, 64);
    + strncpy(i->machine, (const char *)uts_ns->name.machine, 64);
    + strncpy(i->domainname, (const char *)uts_ns->name.domainname, 64);
    +
    + rv = kstate_write_image(ctx, i, sizeof(*i), obj);
    + kfree(i);
    + pr_debug("dump uts_ns %p: ref {%llu, %u}, rv %d\n", uts_ns, (unsigned long long)obj->o_ref.pos, obj->o_ref.id, rv);
    + return rv;
    +}
    +
    +int kstate_dump_all_uts_ns(struct kstate_context *ctx)
    +{
    + struct kstate_object *obj;
    + int rv;
    +
    + for_each_kstate_object(ctx, obj, KSTATE_CTX_UTS_NS) {
    + rv = dump_uts_ns(ctx, obj);
    + if (rv < 0)
    + return rv;
    + }
    + return 0;
    +}
    +
    +int kstate_restore_uts_ns(struct kstate_context *ctx, kstate_ref_t *ref)
    +{
    + struct kstate_image_uts_ns *i;
    + struct uts_namespace *uts_ns;
    + int rv;
    +
    + i = kstate_read_image(ctx, ref, KSTATE_OBJ_UTS_NS, sizeof(*i));
    + if (IS_ERR(i))
    + return PTR_ERR(i);
    +
    + uts_ns = create_uts_ns();
    + if (!uts_ns) {
    + kfree(i);
    + return -ENOMEM;
    + }
    +
    + strlcpy(uts_ns->name.sysname, i->sysname, sizeof(uts_ns->name.sysname));
    + strlcpy(uts_ns->name.nodename, i->nodename, sizeof(uts_ns->name.nodename));
    + strlcpy(uts_ns->name.release, i->release, sizeof(uts_ns->name.release));
    + strlcpy(uts_ns->name.version, i->version, sizeof(uts_ns->name.version));
    + strlcpy(uts_ns->name.machine, i->machine, sizeof(uts_ns->name.machine));
    + strlcpy(uts_ns->name.domainname, i->domainname, sizeof(uts_ns->name.domainname));
    + kfree(i);
    +
    + rv = kstate_restore_object(ctx, uts_ns, KSTATE_CTX_UTS_NS, ref);
    + if (rv < 0)
    + put_uts_ns(uts_ns);
    + pr_debug("restore uts_ns %p: ref {%llu, %u}, rv %d\n", uts_ns, (unsigned long long)ref->pos, ref->id, rv);
    + return rv;
    +}
    +#endif
    --
    1.5.6.5


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