From ebb12db51f6c13b30752fcf506baad4c617b153c Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Wed, 11 Jun 2008 22:04:29 +0200 Subject: Freezer: Introduce PF_FREEZER_NOSIG The freezer currently attempts to distinguish kernel threads from user space tasks by checking if their mm pointer is unset and it does not send fake signals to kernel threads. However, there are kernel threads, mostly related to networking, that behave like user space tasks and may want to be sent a fake signal to be frozen. Introduce the new process flag PF_FREEZER_NOSIG that will be set by default for all kernel threads and make the freezer only send fake signals to the tasks having PF_FREEZER_NOSIG unset. Provide the set_freezable_with_signal() function to be called by the kernel threads that want to be sent a fake signal for freezing. This patch should not change the freezer's observable behavior. Signed-off-by: Rafael J. Wysocki Signed-off-by: Andi Kleen Acked-by: Pavel Machek Signed-off-by: Len Brown --- include/linux/sched.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index 21349173d148..ba2f859c6e4f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1494,6 +1494,7 @@ static inline void put_task_struct(struct task_struct *t) #define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */ #define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */ #define PF_FREEZER_SKIP 0x40000000 /* Freezer should not count it as freezeable */ +#define PF_FREEZER_NOSIG 0x80000000 /* Freezer won't send signals to it */ /* * Only the _current_ task can read/write to tsk->flags, but other -- cgit v1.2.3 From f470021adb9190819c03d6d8c5c860a17480aa6d Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Mon, 24 Mar 2008 18:36:23 -0700 Subject: ptrace children revamp ptrace no longer fiddles with the children/sibling links, and the old ptrace_children list is gone. Now ptrace, whether of one's own children or another's via PTRACE_ATTACH, just uses the new ptraced list instead. There should be no user-visible difference that matters. The only change is the order in which do_wait() sees multiple stopped children and stopped ptrace attachees. Since wait_task_stopped() was changed earlier so it no longer reorders the children list, we already know this won't cause any new problems. Signed-off-by: Roland McGrath --- include/linux/sched.h | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-) (limited to 'include/linux/sched.h') diff --git a/include/linux/sched.h b/include/linux/sched.h index ba2f859c6e4f..1941d8b5cf11 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1062,12 +1062,6 @@ struct task_struct { #endif struct list_head tasks; - /* - * ptrace_list/ptrace_children forms the list of my children - * that were stolen by a ptracer. - */ - struct list_head ptrace_children; - struct list_head ptrace_list; struct mm_struct *mm, *active_mm; @@ -1089,18 +1083,25 @@ struct task_struct { /* * pointers to (original) parent process, youngest child, younger sibling, * older sibling, respectively. (p->father can be replaced with - * p->parent->pid) + * p->real_parent->pid) */ - struct task_struct *real_parent; /* real parent process (when being debugged) */ - struct task_struct *parent; /* parent process */ + struct task_struct *real_parent; /* real parent process */ + struct task_struct *parent; /* recipient of SIGCHLD, wait4() reports */ /* - * children/sibling forms the list of my children plus the - * tasks I'm ptracing. + * children/sibling forms the list of my natural children */ struct list_head children; /* list of my children */ struct list_head sibling; /* linkage in my parent's children list */ struct task_struct *group_leader; /* threadgroup leader */ + /* + * ptraced is the list of tasks this task is using ptrace on. + * This includes both natural children and PTRACE_ATTACH targets. + * p->ptrace_entry is p's link on the p->parent->ptraced list. + */ + struct list_head ptraced; + struct list_head ptrace_entry; + /* PID/PID hash table linkage. */ struct pid_link pids[PIDTYPE_MAX]; struct list_head thread_group; @@ -1876,9 +1877,6 @@ extern void wait_task_inactive(struct task_struct * p); #define wait_task_inactive(p) do { } while (0) #endif -#define remove_parent(p) list_del_init(&(p)->sibling) -#define add_parent(p) list_add_tail(&(p)->sibling,&(p)->parent->children) - #define next_task(p) list_entry(rcu_dereference((p)->tasks.next), struct task_struct, tasks) #define for_each_process(p) \ -- cgit v1.2.3