Relatives and parent notifications have already protected by appropriate kin_lock, so we may do not to take tasklist_lock for writing.
Hovewer, we still need it read locked to protect PGRP and PSID. Signed-off-by: Kirill Tkhai <[email protected]> --- kernel/exit.c | 19 +++++++------------ kernel/ptrace.c | 6 +++--- 2 files changed, 10 insertions(+), 15 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index aeded00..99d7aa3 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -460,8 +460,6 @@ static struct task_struct *find_alive_thread(struct task_struct *p) } static void check_pid_ns_reaper_exit(struct task_struct *father) - __releases(&tasklist_lock) - __acquires(&tasklist_lock) { struct pid_namespace *pid_ns = task_active_pid_ns(father); struct task_struct *reaper; @@ -473,7 +471,7 @@ static void check_pid_ns_reaper_exit(struct task_struct *father) if (likely(reaper != father)) return; - write_lock(&pid_ns->cr_lock); + write_lock_irq(&pid_ns->cr_lock); read_real_parent_lock(father); reaper = find_alive_thread(father); @@ -481,18 +479,16 @@ static void check_pid_ns_reaper_exit(struct task_struct *father) pid_ns->child_reaper = reaper; read_real_parent_unlock(father); - write_unlock(&pid_ns->cr_lock); + write_unlock_irq(&pid_ns->cr_lock); if (reaper) return; - write_unlock_irq(&tasklist_lock); if (unlikely(pid_ns == &init_pid_ns)) { panic("Attempted to kill init! exitcode=0x%08x\n", father->signal->group_exit_code ?: father->exit_code); } zap_pid_ns_processes(pid_ns); - write_lock_irq(&tasklist_lock); } /* @@ -598,7 +594,6 @@ static void forget_original_parent(struct task_struct *father, if (unlikely(!list_empty(&father->ptraced))) exit_ptrace(father, dead); - /* Can drop and reacquire tasklist_lock */ check_pid_ns_reaper_exit(father); /* read_lock() guarantees concurrent thread sees our PF_EXITING */ @@ -609,7 +604,7 @@ static void forget_original_parent(struct task_struct *father, } read_unlock(&father->kin_lock); - read_lock(&task_active_pid_ns(father)->cr_lock); + read_lock_irq(&task_active_pid_ns(father)->cr_lock); reaper = find_double_lock_new_reaper(father); list_for_each_entry(p, &father->children, sibling) { @@ -632,7 +627,7 @@ static void forget_original_parent(struct task_struct *father, list_splice_tail_init(&father->children, &reaper->children); double_write_unlock(&reaper->kin_lock, &father->kin_lock); - read_unlock(&task_active_pid_ns(father)->cr_lock); + read_unlock_irq(&task_active_pid_ns(father)->cr_lock); } /* @@ -645,12 +640,13 @@ static void exit_notify(struct task_struct *tsk, int group_dead) struct task_struct *p, *n; LIST_HEAD(dead); - write_lock_irq(&tasklist_lock); forget_original_parent(tsk, &dead); + read_lock_irq(&tasklist_lock); write_parent_and_real_parent_lock(tsk); if (group_dead) kill_orphaned_pgrp(tsk->group_leader, NULL); + read_unlock(&tasklist_lock); if (unlikely(tsk->ptrace)) { int sig = thread_group_leader(tsk) && @@ -672,8 +668,7 @@ static void exit_notify(struct task_struct *tsk, int group_dead) /* mt-exec, de_thread() is waiting for group leader */ if (unlikely(tsk->signal->notify_count < 0)) wake_up_process(tsk->signal->group_exit_task); - write_parent_and_real_parent_unlock(tsk); - write_unlock_irq(&tasklist_lock); + write_parent_and_real_parent_unlock_irq(tsk); list_for_each_entry_safe(p, n, &dead, ptrace_entry) { list_del_init(&p->ptrace_entry); diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 6785f66..d6e2d0b 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -505,9 +505,9 @@ void exit_ptrace(struct task_struct *tracer, struct list_head *dead) if (!p) break; - write_parent_and_real_parent_lock(p); + write_parent_and_real_parent_lock_irq(p); if (p->parent != tracer) { - write_parent_and_real_parent_unlock(p); + write_parent_and_real_parent_unlock_irq(p); continue; } @@ -517,7 +517,7 @@ void exit_ptrace(struct task_struct *tracer, struct list_head *dead) if (__ptrace_detach(tracer, p)) list_add(&p->ptrace_entry, dead); - write_parent_and_real_parent_unlock(p); + write_parent_and_real_parent_unlock_irq(p); } rcu_read_unlock(); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
