pid namespaces: introduce struct upid (4c3f2ead) · Commits · 戴 / test

Since task will be visible from different pid namespaces each of them have to be addressed by multiple pids. struct upid is to store the information about which id refers to which namespace. The constuciton looks like this. Each struct pid carried the reference counter and the list of tasks attached to this pid. At its end it has a variable length array of struct upid-s. Each struct upid has a numerical id (pid itself), pointer to the namespace, this ID is valid in and is hashed into a pid_hash for searching the pids. The nr and pid_chain fields are kept in struct pid for a while to make kernel still work (no patch initialize the upids yet), but it will be removed at the end of this series when we switch to upids completely. Signed-off-by:

Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by:

Pavel Emelyanov <xemul@openvz.org> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Paul Menage <menage@google.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/init_task.h

+6 −0

Original line number	Original line	Diff line number	Diff line
	@@ -103,6 +103,12 @@ extern struct group_info init_groups;
	{ .first = &init_task.pids[PIDTYPE_SID].node }, \		{ .first = &init_task.pids[PIDTYPE_SID].node }, \
	}, \		}, \
	.rcu = RCU_HEAD_INIT, \		.rcu = RCU_HEAD_INIT, \
			.level = 0, \
			.numbers = { { \
			.nr = 0, \
			.ns = &init_pid_ns, \
			.pid_chain = { .next = NULL, .pprev = NULL }, \
			}, } \
	}		}

	#define INIT_PID_LINK(type) \		#define INIT_PID_LINK(type) \

include/linux/pid.h

+16 −0

Original line number	Original line	Diff line number	Diff line
	@@ -40,6 +40,20 @@ enum pid_type
	* processes.		* processes.
	*/		*/


			/*
			* struct upid is used to get the id of the struct pid, as it is
			* seen in particular namespace. Later the struct pid is found with
			* find_pid_ns() using the int nr and struct pid_namespace *ns.
			*/

			struct upid {
			/* Try to keep pid_chain in the same cacheline as nr for find_pid */
			int nr;
			struct pid_namespace *ns;
			struct hlist_node pid_chain;
			};

	struct pid		struct pid
	{		{
	atomic_t count;		atomic_t count;
	@@ -49,6 +63,8 @@ struct pid
	/* lists of tasks that use this pid */		/* lists of tasks that use this pid */
	struct hlist_head tasks[PIDTYPE_MAX];		struct hlist_head tasks[PIDTYPE_MAX];
	struct rcu_head rcu;		struct rcu_head rcu;
			int level;
			struct upid numbers[1];
	};		};

	extern struct pid init_struct_pid;		extern struct pid init_struct_pid;

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