From 6d29b940714eb1ded8053d0f2db457e6a4cd85c4 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sat, 20 Aug 2011 11:31:40 +0200 Subject: [PATCH] freezer: clean up freeze_processes() failure path freeze_processes() failure path is rather messy. Freezing is canceled for workqueues and tasks which aren't frozen yet but frozen tasks are left alone and should be thawed by the caller and of course some callers (xen and kexec) didn't do it. This patch updates __thaw_task() to handle cancelation correctly and makes thaw_processes() call thaw_processes() on failure instead so that the system is fully thawed on failure. Unnecessary thaw_processes() calls are removed from kernel/power/hibernate.c and user.c. Signed-off-by: Tejun Heo --- include/linux/freezer.h | 1 - kernel/freezer.c | 25 +++++++++---------------- kernel/power/hibernate.c | 15 ++------------- kernel/power/process.c | 10 ++-------- kernel/power/user.c | 4 +--- 5 files changed, 14 insertions(+), 41 deletions(-) diff --git a/include/linux/freezer.h b/include/linux/freezer.h index 59a6e972b836..13559a808098 100644 --- a/include/linux/freezer.h +++ b/include/linux/freezer.h @@ -60,7 +60,6 @@ static inline bool try_to_freeze(void) } extern bool freeze_task(struct task_struct *p, bool sig_only); -extern void cancel_freezing(struct task_struct *p); extern bool __set_freezable(bool with_signal); #ifdef CONFIG_CGROUP_FREEZER diff --git a/kernel/freezer.c b/kernel/freezer.c index 82332bb28666..7506ef39150f 100644 --- a/kernel/freezer.c +++ b/kernel/freezer.c @@ -126,21 +126,6 @@ out_unlock: return ret; } -void cancel_freezing(struct task_struct *p) -{ - unsigned long flags; - - spin_lock_irqsave(&freezer_lock, flags); - if (freezing(p)) { - pr_debug(" clean up: %s\n", p->comm); - clear_freeze_flag(p); - spin_lock(&p->sighand->siglock); - recalc_sigpending_and_wake(p); - spin_unlock(&p->sighand->siglock); - } - spin_unlock_irqrestore(&freezer_lock, flags); -} - void __thaw_task(struct task_struct *p) { unsigned long flags; @@ -150,11 +135,19 @@ void __thaw_task(struct task_struct *p) * be visible to @p as waking up implies wmb. Waking up inside * freezer_lock also prevents wakeups from leaking outside * refrigerator. + * + * If !FROZEN, @p hasn't reached refrigerator, recalc sigpending to + * avoid leaving dangling TIF_SIGPENDING behind. */ spin_lock_irqsave(&freezer_lock, flags); clear_freeze_flag(p); - if (frozen(p)) + if (frozen(p)) { wake_up_process(p); + } else { + spin_lock(&p->sighand->siglock); + recalc_sigpending_and_wake(p); + spin_unlock(&p->sighand->siglock); + } spin_unlock_irqrestore(&freezer_lock, flags); } diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index 8f7b1db1ece1..5fed34d7ccec 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -586,17 +586,6 @@ static void power_down(void) while(1); } -static int prepare_processes(void) -{ - int error = 0; - - if (freeze_processes()) { - error = -EBUSY; - thaw_processes(); - } - return error; -} - /** * hibernate - Carry out system hibernation, including saving the image. */ @@ -629,7 +618,7 @@ int hibernate(void) sys_sync(); printk("done.\n"); - error = prepare_processes(); + error = freeze_processes(); if (error) goto Finish; @@ -776,7 +765,7 @@ static int software_resume(void) goto close_finish; pr_debug("PM: Preparing processes for restore.\n"); - error = prepare_processes(); + error = freeze_processes(); if (error) { swsusp_close(FMODE_READ); goto Done; diff --git a/kernel/power/process.c b/kernel/power/process.c index 7618909ba868..f8012f2f5cdf 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -91,11 +91,6 @@ static int try_to_freeze_tasks(bool sig_only) elapsed_csecs = elapsed_csecs64; if (todo) { - /* This does not unfreeze processes that are already frozen - * (we have slightly ugly calling convention in that respect, - * and caller must call thaw_processes() if something fails), - * but it cleans up leftover PF_FREEZE requests. - */ printk("\n"); printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds " "(%d tasks refusing to freeze, wq_busy=%d):\n", @@ -103,14 +98,11 @@ static int try_to_freeze_tasks(bool sig_only) elapsed_csecs / 100, elapsed_csecs % 100, todo - wq_busy, wq_busy); - thaw_workqueues(); - read_lock(&tasklist_lock); do_each_thread(g, p) { if (!wakeup && !freezer_should_skip(p) && freezing(p) && !frozen(p)) sched_show_task(p); - cancel_freezing(p); } while_each_thread(g, p); read_unlock(&tasklist_lock); } else { @@ -142,6 +134,8 @@ int freeze_processes(void) oom_killer_disable(); Exit: + if (error) + thaw_processes(); BUG_ON(in_atomic()); printk("\n"); diff --git a/kernel/power/user.c b/kernel/power/user.c index 42ddbc6f0de6..afe7737a0eda 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -256,10 +256,8 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd, break; error = freeze_processes(); - if (error) { - thaw_processes(); + if (error) usermodehelper_enable(); - } if (!error) data->frozen = 1; break; -- 2.39.5