On Tue, Aug 10, 2010 at 09:20:53AM -0700, Dan Smith wrote:
> Checkpoint/Restart needs to have a pointer to the ipc_namespace that the
> sem_undo_list applies to in order to properly bring up and tear down
> the object hash. This patch adds a pointer to the namespace to the list
> structure, as well as breaks out the allocation of the undo list to a
> separate function (which is needed in a later C/R patch anyway).
>
> Signed-off-by: Dan Smith <danms@xxxxxxxxxx>
> ---
Reviewed-by: Matt Helsley <matthltc@xxxxxxxxxx>
> include/linux/sem.h | 2 ++
> ipc/sem.c | 30 +++++++++++++++++++++---------
> 2 files changed, 23 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/sem.h b/include/linux/sem.h
> index 8a4adbe..8cf9636 100644
> --- a/include/linux/sem.h
> +++ b/include/linux/sem.h
> @@ -127,12 +127,14 @@ struct sem_undo {
> short * semadj; /* array of adjustments, one per semaphore */
> };
>
> +struct ipc_namespace;
> /* sem_undo_list controls shared access to the list of sem_undo structures
> * that may be shared among all a CLONE_SYSVSEM task group.
> */
> struct sem_undo_list {
> atomic_t refcnt;
> spinlock_t lock;
> + struct ipc_namespace *ipc_ns;
> struct list_head list_proc;
> };
>
> diff --git a/ipc/sem.c b/ipc/sem.c
> index 37da85e..e439b73 100644
> --- a/ipc/sem.c
> +++ b/ipc/sem.c
> @@ -983,6 +983,21 @@ asmlinkage long SyS_semctl(int semid, int semnum, int cmd, union semun arg)
> SYSCALL_ALIAS(sys_semctl, SyS_semctl);
> #endif
>
> +static struct sem_undo_list *alloc_undo_list(struct ipc_namespace *ipc_ns)
> +{
> + struct sem_undo_list *undo_list;
> +
> + undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
> + if (undo_list == NULL)
> + return NULL;
> + spin_lock_init(&undo_list->lock);
> + atomic_set(&undo_list->refcnt, 1);
> + INIT_LIST_HEAD(&undo_list->list_proc);
> + undo_list->ipc_ns = ipc_ns;
> +
> + return undo_list;
> +}
> +
> /* If the task doesn't already have a undo_list, then allocate one
> * here. We guarantee there is only one thread using this undo list,
> * and current is THE ONE
> @@ -994,19 +1009,16 @@ SYSCALL_ALIAS(sys_semctl, SyS_semctl);
> *
> * This can block, so callers must hold no locks.
> */
> -static inline int get_undo_list(struct sem_undo_list **undo_listp)
> +static inline int get_undo_list(struct sem_undo_list **undo_listp,
> + struct ipc_namespace *ipc_ns)
> {
> struct sem_undo_list *undo_list;
>
> undo_list = current->sysvsem.undo_list;
> if (!undo_list) {
> - undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL);
> - if (undo_list == NULL)
> + undo_list = alloc_undo_list(ipc_ns);
> + if (!undo_list)
> return -ENOMEM;
> - spin_lock_init(&undo_list->lock);
> - atomic_set(&undo_list->refcnt, 1);
> - INIT_LIST_HEAD(&undo_list->list_proc);
> -
> current->sysvsem.undo_list = undo_list;
> }
> *undo_listp = undo_list;
> @@ -1057,7 +1069,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid)
> int nsems;
> int error;
>
> - error = get_undo_list(&ulp);
> + error = get_undo_list(&ulp, ns);
> if (error)
> return ERR_PTR(error);
>
> @@ -1328,7 +1340,7 @@ int copy_semundo(unsigned long clone_flags, struct task_struct *tsk)
> int error;
>
> if (clone_flags & CLONE_SYSVSEM) {
> - error = get_undo_list(&undo_list);
> + error = get_undo_list(&undo_list, tsk->nsproxy->ipc_ns);
> if (error)
> return error;
> atomic_inc(&undo_list->refcnt);
> --
> 1.7.1.1
>
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