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authorEric W. Biederman <ebiederm@xmission.com>2017-06-04 11:32:13 +0200
committerEric W. Biederman <ebiederm@xmission.com>2018-07-21 17:43:12 +0200
commit6883f81aac6f44e7df70a6af189b3689ff52cbfb (patch)
tree184e376d23aa5ea7321e22f23dd78a3c77c74a63 /kernel
parentpids: Move the pgrp and session pid pointers from task_struct to signal_struct (diff)
downloadlinux-6883f81aac6f44e7df70a6af189b3689ff52cbfb.tar.xz
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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: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/core.c2
-rw-r--r--kernel/exit.c1
-rw-r--r--kernel/fork.c3
-rw-r--r--kernel/pid.c2
-rw-r--r--kernel/time/itimer.c5
-rw-r--r--kernel/time/posix-cpu-timers.c2
6 files changed, 8 insertions, 7 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 80cca2b30c4f..9025b1796ca8 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1334,7 +1334,7 @@ static u32 perf_event_pid_type(struct perf_event *event, struct task_struct *p,
static u32 perf_event_pid(struct perf_event *event, struct task_struct *p)
{
- return perf_event_pid_type(event, p, __PIDTYPE_TGID);
+ return perf_event_pid_type(event, p, PIDTYPE_TGID);
}
static u32 perf_event_tid(struct perf_event *event, struct task_struct *p)
diff --git a/kernel/exit.c b/kernel/exit.c
index 16432428fc6c..25582b442955 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -73,6 +73,7 @@ static void __unhash_process(struct task_struct *p, bool group_dead)
nr_threads--;
detach_pid(p, PIDTYPE_PID);
if (group_dead) {
+ detach_pid(p, PIDTYPE_TGID);
detach_pid(p, PIDTYPE_PGID);
detach_pid(p, PIDTYPE_SID);
diff --git a/kernel/fork.c b/kernel/fork.c
index d2952162399b..cc5be0d01ce6 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1946,6 +1946,7 @@ static __latent_entropy struct task_struct *copy_process(
init_task_pid(p, PIDTYPE_PID, pid);
if (thread_group_leader(p)) {
+ init_task_pid(p, PIDTYPE_TGID, pid);
init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
init_task_pid(p, PIDTYPE_SID, task_session(current));
@@ -1954,7 +1955,6 @@ static __latent_entropy struct task_struct *copy_process(
p->signal->flags |= SIGNAL_UNKILLABLE;
}
- p->signal->leader_pid = pid;
p->signal->tty = tty_kref_get(current->signal->tty);
/*
* Inherit has_child_subreaper flag under the same
@@ -1965,6 +1965,7 @@ static __latent_entropy struct task_struct *copy_process(
p->real_parent->signal->is_child_subreaper;
list_add_tail(&p->sibling, &p->real_parent->children);
list_add_tail_rcu(&p->tasks, &init_task.tasks);
+ attach_pid(p, PIDTYPE_TGID);
attach_pid(p, PIDTYPE_PGID);
attach_pid(p, PIDTYPE_SID);
__this_cpu_inc(process_counts);
diff --git a/kernel/pid.c b/kernel/pid.c
index f8486d2e2346..de1cfc4f75a2 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -269,8 +269,6 @@ static struct pid **task_pid_ptr(struct task_struct *task, enum pid_type type)
{
return (type == PIDTYPE_PID) ?
&task->thread_pid :
- (type == __PIDTYPE_TGID) ?
- &task->signal->leader_pid :
&task->signal->pids[type];
}
diff --git a/kernel/time/itimer.c b/kernel/time/itimer.c
index f26acef5d7b4..9a65713c8309 100644
--- a/kernel/time/itimer.c
+++ b/kernel/time/itimer.c
@@ -139,9 +139,10 @@ enum hrtimer_restart it_real_fn(struct hrtimer *timer)
{
struct signal_struct *sig =
container_of(timer, struct signal_struct, real_timer);
+ struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
- trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
- kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
+ trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
+ kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
return HRTIMER_NORESTART;
}
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 5a6251ac6f7a..40e6fae46cec 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -895,7 +895,7 @@ static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
trace_itimer_expire(signo == SIGPROF ?
ITIMER_PROF : ITIMER_VIRTUAL,
- tsk->signal->leader_pid, cur_time);
+ task_tgid(tsk), cur_time);
__group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
}