From: Pavel Emelyanov With pid namespaces this field is now dangerous to use explicitly, so hide it behind the helpers. Also the pid and pgrp fields o task_struct and signal_struct are to be deprecated. Unfortunately this patch cannot be sent right now as this leads to tons of warnings, so start isolating them, and deprecate later. Actually the p->tgid == pid has to be changed to has_group_leader_pid(), but Oleg pointed out that in case of posix cpu timers this is the same, and thread_group_leader() is more preferable. Signed-off-by: Pavel Emelyanov Acked-by: Oleg Nesterov Cc: Sukadev Bhattiprolu Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton --- fs/exec.c | 4 ++-- fs/proc/base.c | 2 +- include/linux/sched.h | 6 ++++++ kernel/posix-cpu-timers.c | 12 ++++++------ kernel/posix-timers.c | 4 ++-- kernel/ptrace.c | 2 +- kernel/signal.c | 2 +- mm/oom_kill.c | 2 +- 8 files changed, 20 insertions(+), 14 deletions(-) diff -puN fs/exec.c~isolate-some-explicit-usage-of-task-tgid fs/exec.c --- a/fs/exec.c~isolate-some-explicit-usage-of-task-tgid +++ a/fs/exec.c @@ -843,8 +843,8 @@ static int de_thread(struct task_struct */ tsk->start_time = leader->start_time; - BUG_ON(leader->tgid != tsk->tgid); - BUG_ON(tsk->pid == tsk->tgid); + BUG_ON(!same_thread_group(leader, tsk)); + BUG_ON(has_group_leader_pid(tsk)); /* * An exec() starts a new thread group with the * TGID of the previous thread group. Rehash the diff -puN fs/proc/base.c~isolate-some-explicit-usage-of-task-tgid fs/proc/base.c --- a/fs/proc/base.c~isolate-some-explicit-usage-of-task-tgid +++ a/fs/proc/base.c @@ -2474,7 +2474,7 @@ static struct dentry *proc_task_lookup(s rcu_read_unlock(); if (!task) goto out; - if (leader->tgid != task->tgid) + if (!same_thread_group(leader, task)) goto out_drop_task; result = proc_task_instantiate(dir, dentry, task, NULL); diff -puN include/linux/sched.h~isolate-some-explicit-usage-of-task-tgid include/linux/sched.h --- a/include/linux/sched.h~isolate-some-explicit-usage-of-task-tgid +++ a/include/linux/sched.h @@ -1691,6 +1691,12 @@ static inline int has_group_leader_pid(s return p->pid == p->tgid; } +static inline +int same_thread_group(struct task_struct *p1, struct task_struct *p2) +{ + return p1->tgid == p2->tgid; +} + static inline struct task_struct *next_thread(const struct task_struct *p) { return list_entry(rcu_dereference(p->thread_group.next), diff -puN kernel/posix-cpu-timers.c~isolate-some-explicit-usage-of-task-tgid kernel/posix-cpu-timers.c --- a/kernel/posix-cpu-timers.c~isolate-some-explicit-usage-of-task-tgid +++ a/kernel/posix-cpu-timers.c @@ -21,8 +21,8 @@ static int check_clock(const clockid_t w read_lock(&tasklist_lock); p = find_task_by_pid(pid); - if (!p || (CPUCLOCK_PERTHREAD(which_clock) ? - p->tgid != current->tgid : p->tgid != pid)) { + if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ? + same_thread_group(p, current) : thread_group_leader(p))) { error = -EINVAL; } read_unlock(&tasklist_lock); @@ -308,13 +308,13 @@ int posix_cpu_clock_get(const clockid_t p = find_task_by_pid(pid); if (p) { if (CPUCLOCK_PERTHREAD(which_clock)) { - if (p->tgid == current->tgid) { + if (same_thread_group(p, current)) { error = cpu_clock_sample(which_clock, p, &rtn); } } else { read_lock(&tasklist_lock); - if (p->tgid == pid && p->signal) { + if (thread_group_leader(p) && p->signal) { error = cpu_clock_sample_group(which_clock, p, &rtn); @@ -355,7 +355,7 @@ int posix_cpu_timer_create(struct k_itim p = current; } else { p = find_task_by_pid(pid); - if (p && p->tgid != current->tgid) + if (p && !same_thread_group(p, current)) p = NULL; } } else { @@ -363,7 +363,7 @@ int posix_cpu_timer_create(struct k_itim p = current->group_leader; } else { p = find_task_by_pid(pid); - if (p && p->tgid != pid) + if (p && !thread_group_leader(p)) p = NULL; } } diff -puN kernel/posix-timers.c~isolate-some-explicit-usage-of-task-tgid kernel/posix-timers.c --- a/kernel/posix-timers.c~isolate-some-explicit-usage-of-task-tgid +++ a/kernel/posix-timers.c @@ -404,7 +404,7 @@ static struct task_struct * good_sigeven if ((event->sigev_notify & SIGEV_THREAD_ID ) && (!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) || - rtn->tgid != current->tgid || + !same_thread_group(rtn, current) || (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL)) return NULL; @@ -608,7 +608,7 @@ static struct k_itimer * lock_timer(time spin_lock(&timr->it_lock); if ((timr->it_id != timer_id) || !(timr->it_process) || - timr->it_process->tgid != current->tgid) { + !same_thread_group(timr->it_process, current)) { spin_unlock(&timr->it_lock); spin_unlock_irqrestore(&idr_lock, *flags); timr = NULL; diff -puN kernel/ptrace.c~isolate-some-explicit-usage-of-task-tgid kernel/ptrace.c --- a/kernel/ptrace.c~isolate-some-explicit-usage-of-task-tgid +++ a/kernel/ptrace.c @@ -169,7 +169,7 @@ int ptrace_attach(struct task_struct *ta retval = -EPERM; if (task->pid <= 1) goto out; - if (task->tgid == current->tgid) + if (same_thread_group(task, current)) goto out; repeat: diff -puN kernel/signal.c~isolate-some-explicit-usage-of-task-tgid kernel/signal.c --- a/kernel/signal.c~isolate-some-explicit-usage-of-task-tgid +++ a/kernel/signal.c @@ -1152,7 +1152,7 @@ static int kill_something_info(int sig, read_lock(&tasklist_lock); for_each_process(p) { - if (p->pid > 1 && p->tgid != current->tgid) { + if (p->pid > 1 && !same_thread_group(p, current)) { int err = group_send_sig_info(sig, info, p); ++count; if (err != -EPERM) diff -puN mm/oom_kill.c~isolate-some-explicit-usage-of-task-tgid mm/oom_kill.c --- a/mm/oom_kill.c~isolate-some-explicit-usage-of-task-tgid +++ a/mm/oom_kill.c @@ -330,7 +330,7 @@ static int oom_kill_task(struct task_str * to memory reserves though, otherwise we might deplete all memory. */ do_each_thread(g, q) { - if (q->mm == mm && q->tgid != p->tgid) + if (q->mm == mm && !same_thread_group(q, p)) force_sig(SIGKILL, q); } while_each_thread(g, q); _