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Commit 6883f81a authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

pid: Implement PIDTYPE_TGID 



Everywhere except in the pid array we distinguish between a tasks pid and
a tasks tgid (thread group id).  Even in the enumeration we want that
distinction sometimes so we have added __PIDTYPE_TGID.  With leader_pid
we almost have an implementation of PIDTYPE_TGID in struct signal_struct.

Add PIDTYPE_TGID as a first class member of the pid_type enumeration and
into the pids array.  Then remove the __PIDTYPE_TGID special case and the
leader_pid in signal_struct.

The net size increase is just an extra pointer added to struct pid and
an extra pair of pointers of an hlist_node added to task_struct.

The effect on code maintenance is the removal of a number of special
cases today and the potential to remove many more special cases as
PIDTYPE_TGID gets used to it's fullest.  The long term potential
is allowing zombie thread group leaders to exit, which will remove
a lot more special cases in the code.

Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
parent 2c470475

arch/ia64/kernel/asm-offsets.c

+1 −1
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ void foo(void) 
	DEFINE(IA64_SIGNAL_GROUP_STOP_COUNT_OFFSET,offsetof (struct signal_struct,

							     group_stop_count));

	DEFINE(IA64_SIGNAL_SHARED_PENDING_OFFSET,offsetof (struct signal_struct, shared_pending));

	DEFINE(IA64_SIGNAL_LEADER_PID_OFFSET, offsetof (struct signal_struct, leader_pid));

	DEFINE(IA64_SIGNAL_PIDS_TGID_OFFSET, offsetof (struct signal_struct, pids[PIDTYPE_TGID]));



	BLANK();

arch/ia64/kernel/fsys.S

+2 −2
Original line number Diff line number Diff line
@@ -68,10 +68,10 @@ ENTRY(fsys_getpid) 
	add r9=TI_FLAGS+IA64_TASK_SIZE,r16

	;;

	ld4 r9=[r9]

	add r17=IA64_SIGNAL_LEADER_PID_OFFSET,r17

	add r17=IA64_SIGNAL_PIDS_TGID_OFFSET,r17

	;;

	and r9=TIF_ALLWORK_MASK,r9

	ld8 r17=[r17]				// r17 = current->signal->leader_pid

	ld8 r17=[r17]				// r17 = current->signal->pids[PIDTYPE_TGID]

	;;

	add r8=IA64_PID_LEVEL_OFFSET,r17

	;;

arch/s390/kernel/perf_cpum_sf.c

+1 −1
Original line number Diff line number Diff line
@@ -665,7 +665,7 @@ static void cpumsf_output_event_pid(struct perf_event *event, 
		goto out;



	/* Update the process ID (see also kernel/events/core.c) */

	data->tid_entry.pid = cpumsf_pid_type(event, pid, __PIDTYPE_TGID);

	data->tid_entry.pid = cpumsf_pid_type(event, pid, PIDTYPE_TGID);

	data->tid_entry.tid = cpumsf_pid_type(event, pid, PIDTYPE_PID);



	perf_output_sample(&handle, &header, data, event);

fs/exec.c

+1 −0
Original line number Diff line number Diff line
@@ -1146,6 +1146,7 @@ static int de_thread(struct task_struct *tsk) 
		 */

		tsk->pid = leader->pid;

		change_pid(tsk, PIDTYPE_PID, task_pid(leader));

		transfer_pid(leader, tsk, PIDTYPE_TGID);

		transfer_pid(leader, tsk, PIDTYPE_PGID);

		transfer_pid(leader, tsk, PIDTYPE_SID);

include/linux/pid.h

+1 −2
Original line number Diff line number Diff line
@@ -7,11 +7,10 @@ 
enum pid_type

{

	PIDTYPE_PID,

	PIDTYPE_TGID,

	PIDTYPE_PGID,

	PIDTYPE_SID,

	PIDTYPE_MAX,

	/* only valid to __task_pid_nr_ns() */

	__PIDTYPE_TGID

};



/*