[EMAIL PROTECTED] wrote:
> This patch adds the main containers framework - the container
> filesystem, and the basic structures for tracking membership and
> associating subsystem state objects to tasks.
[snip]
> +*** notify_on_release is disabled in the current patch set. It may be
> +*** reactivated in a future patch in a less-intrusive manner
> +
Won't this break user space tools for cpusets?
[snip]
> +See kernel/container.c for more details.
> +
> +Subsystems can take/release the container_mutex via the functions
> +container_lock()/container_unlock(), and can
> +take/release the callback_mutex via the functions
> +container_lock()/container_unlock().
> +
Hmm.. looks like a documentation error. Both mutex's are obtained through
container_lock/container_unlock ?
> +Accessing a task's container pointer may be done in the following ways:
> +- while holding container_mutex
> +- while holding the task's alloc_lock (via task_lock())
> +- inside an rcu_read_lock() section via rcu_dereference()
> +
container_mutex() and task_lock() can be used for changing the pointer?
Could you please explain this a bit further.
[snip]
> +int populate(struct container_subsys *ss, struct container *cont)
> +LL=none
> +
> +Called after creation of a container to allow a subsystem to populate
> +the container directory with file entries. The subsystem should make
> +calls to container_add_file() with objects of type cftype (see
> +include/linux/container.h for details). Note that although this
> +method can return an error code, the error code is currently not
> +always handled well.
We needed the equivalent of container_remove_file() to be called
if container_add_file() failed.
[snip]
> +struct container {
> + unsigned long flags; /* "unsigned long" so bitops work */
> +
> + /* count users of this container. >0 means busy, but doesn't
> + * necessarily indicate the number of tasks in the
> + * container */
> + atomic_t count;
> +
> + /*
> + * We link our 'sibling' struct into our parent's 'children'.
> + * Our children link their 'sibling' into our 'children'.
> + */
> + struct list_head sibling; /* my parent's children */
> + struct list_head children; /* my children */
> +
> + struct container *parent; /* my parent */
> + struct dentry *dentry; /* container fs entry */
> +
> + /* Private pointers for each registered subsystem */
> + struct container_subsys_state *subsys[CONTAINER_SUBSYS_COUNT];
> +
> + struct containerfs_root *root;
> + struct container *top_container;
> +};
Can't we derive the top_container from containerfs_root?
> +
> +/* struct cftype:
> + *
> + * The files in the container filesystem mostly have a very simple read/write
> + * handling, some common function will take care of it. Nevertheless some
> cases
> + * (read tasks) are special and therefore I define this structure for every
> + * kind of file.
> + *
> + *
> + * When reading/writing to a file:
> + * - the container to use in file->f_dentry->d_parent->d_fsdata
> + * - the 'cftype' of the file is file->f_dentry->d_fsdata
> + */
> +
> +struct inode;
> +#define MAX_CFTYPE_NAME 64
> +struct cftype {
> + /* By convention, the name should begin with the name of the
> + * subsystem, followed by a period */
> + char name[MAX_CFTYPE_NAME];
> + int private;
> + int (*open) (struct inode *inode, struct file *file);
> + ssize_t (*read) (struct container *cont, struct cftype *cft,
> + struct file *file,
> + char __user *buf, size_t nbytes, loff_t *ppos);
> + u64 (*read_uint) (struct container *cont, struct cftype *cft);
Is this a new callback, a specialization of the read() callback?
> + ssize_t (*write) (struct container *cont, struct cftype *cft,
> + struct file *file,
> + const char __user *buf, size_t nbytes, loff_t *ppos);
> + int (*release) (struct inode *inode, struct file *file);
> +};
> +
[snip]
--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
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