diff options
| -rw-r--r-- | include/linux/freezer.h | 9 | ||||
| -rw-r--r-- | kernel/exit.c | 3 | ||||
| -rw-r--r-- | kernel/power/process.c | 64 |
3 files changed, 41 insertions, 35 deletions
diff --git a/include/linux/freezer.h b/include/linux/freezer.h index 2d38b1a74662..c8e02de737f6 100644 --- a/include/linux/freezer.h +++ b/include/linux/freezer.h @@ -25,7 +25,7 @@ static inline int freezing(struct task_struct *p) /* * Request that a process be frozen */ -static inline void freeze(struct task_struct *p) +static inline void set_freeze_flag(struct task_struct *p) { set_tsk_thread_flag(p, TIF_FREEZE); } @@ -33,7 +33,7 @@ static inline void freeze(struct task_struct *p) /* * Sometimes we may need to cancel the previous 'freeze' request */ -static inline void do_not_freeze(struct task_struct *p) +static inline void clear_freeze_flag(struct task_struct *p) { clear_tsk_thread_flag(p, TIF_FREEZE); } @@ -56,7 +56,7 @@ static inline int thaw_process(struct task_struct *p) wake_up_process(p); return 1; } - clear_tsk_thread_flag(p, TIF_FREEZE); + clear_freeze_flag(p); task_unlock(p); return 0; } @@ -129,7 +129,8 @@ static inline void set_freezable(void) #else static inline int frozen(struct task_struct *p) { return 0; } static inline int freezing(struct task_struct *p) { return 0; } -static inline void freeze(struct task_struct *p) { BUG(); } +static inline void set_freeze_flag(struct task_struct *p) {} +static inline void clear_freeze_flag(struct task_struct *p) {} static inline int thaw_process(struct task_struct *p) { return 1; } static inline void refrigerator(void) {} diff --git a/kernel/exit.c b/kernel/exit.c index e8af8d0c2483..464c2b172f07 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -45,6 +45,7 @@ #include <linux/resource.h> #include <linux/blkdev.h> #include <linux/task_io_accounting_ops.h> +#include <linux/freezer.h> #include <asm/uaccess.h> #include <asm/unistd.h> @@ -594,6 +595,8 @@ static void exit_mm(struct task_struct * tsk) tsk->mm = NULL; up_read(&mm->mmap_sem); enter_lazy_tlb(mm, current); + /* We don't want this task to be frozen prematurely */ + clear_freeze_flag(tsk); task_unlock(tsk); mmput(mm); } diff --git a/kernel/power/process.c b/kernel/power/process.c index b850173e7561..e1bcdedd1464 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -40,7 +40,7 @@ static inline void frozen_process(void) current->flags |= PF_FROZEN; wmb(); } - clear_tsk_thread_flag(current, TIF_FREEZE); + clear_freeze_flag(current); } /* Refrigerator is place where frozen processes are stored :-). */ @@ -75,17 +75,16 @@ void refrigerator(void) current->state = save; } -static inline void freeze_process(struct task_struct *p) +static void freeze_task(struct task_struct *p) { unsigned long flags; if (!freezing(p)) { rmb(); if (!frozen(p)) { + set_freeze_flag(p); if (p->state == TASK_STOPPED) force_sig_specific(SIGSTOP, p); - - freeze(p); spin_lock_irqsave(&p->sighand->siglock, flags); signal_wake_up(p, p->state == TASK_STOPPED); spin_unlock_irqrestore(&p->sighand->siglock, flags); @@ -99,18 +98,13 @@ static void cancel_freezing(struct task_struct *p) if (freezing(p)) { pr_debug(" clean up: %s\n", p->comm); - do_not_freeze(p); + clear_freeze_flag(p); spin_lock_irqsave(&p->sighand->siglock, flags); recalc_sigpending_and_wake(p); spin_unlock_irqrestore(&p->sighand->siglock, flags); } } -static inline int is_user_space(struct task_struct *p) -{ - return p->mm && !(p->flags & PF_BORROWED_MM); -} - static unsigned int try_to_freeze_tasks(int freeze_user_space) { struct task_struct *g, *p; @@ -122,20 +116,34 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space) todo = 0; read_lock(&tasklist_lock); do_each_thread(g, p) { - if (!freezeable(p)) - continue; - - if (frozen(p)) + if (frozen(p) || !freezeable(p)) continue; - if (p->state == TASK_TRACED && frozen(p->parent)) { - cancel_freezing(p); - continue; + if (freeze_user_space) { + if (p->state == TASK_TRACED && + frozen(p->parent)) { + cancel_freezing(p); + continue; + } + /* + * Kernel threads should not have TIF_FREEZE set + * at this point, so we must ensure that either + * p->mm is not NULL *and* PF_BORROWED_MM is + * unset, or TIF_FRREZE is left unset. + * The task_lock() is necessary to prevent races + * with exit_mm() or use_mm()/unuse_mm() from + * occuring. + */ + task_lock(p); + if (!p->mm || (p->flags & PF_BORROWED_MM)) { + task_unlock(p); + continue; + } + freeze_task(p); + task_unlock(p); + } else { + freeze_task(p); } - if (freeze_user_space && !is_user_space(p)) - continue; - - freeze_process(p); if (!freezer_should_skip(p)) todo++; } while_each_thread(g, p); @@ -152,22 +160,16 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space) * but it cleans up leftover PF_FREEZE requests. */ printk("\n"); - printk(KERN_ERR "Stopping %s timed out after %d seconds " + printk(KERN_ERR "Freezing of %s timed out after %d seconds " "(%d tasks refusing to freeze):\n", - freeze_user_space ? "user space processes" : - "kernel threads", + freeze_user_space ? "user space " : "tasks ", TIMEOUT / HZ, todo); show_state(); read_lock(&tasklist_lock); do_each_thread(g, p) { - if (freeze_user_space && !is_user_space(p)) - continue; - task_lock(p); - if (freezeable(p) && !frozen(p) && - !freezer_should_skip(p)) + if (freezing(p) && !freezer_should_skip(p)) printk(KERN_ERR " %s\n", p->comm); - cancel_freezing(p); task_unlock(p); } while_each_thread(g, p); @@ -211,7 +213,7 @@ static void thaw_tasks(int thaw_user_space) if (!freezeable(p)) continue; - if (is_user_space(p) == !thaw_user_space) + if (!p->mm == thaw_user_space) continue; thaw_process(p); |