From ba96a0c88098697a63e80157718b7440414ed24d Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Wed, 23 May 2007 13:57:25 -0700 Subject: freezer: fix vfork problem Currently try_to_freeze_tasks() has to wait until all of the vforked processes exit and for this reason every user can make it fail. To fix this problem we can introduce the additional process flag PF_FREEZER_SKIP to be used by tasks that do not want to be counted as freezable by the freezer and want to have TIF_FREEZE set nevertheless. Then, this flag can be set by tasks using sys_vfork() before they call wait_for_completion(&vfork) and cleared after they have woken up. After clearing it, the tasks should call try_to_freeze() as soon as possible. Signed-off-by: Rafael J. Wysocki Cc: Gautham R Shenoy Cc: Oleg Nesterov Cc: Pavel Machek Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/power/process.c | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-) (limited to 'kernel/power') diff --git a/kernel/power/process.c b/kernel/power/process.c index 02e490e311eb..eefca8581fa0 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -120,22 +120,12 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space) cancel_freezing(p); continue; } - if (is_user_space(p)) { - if (!freeze_user_space) - continue; - - /* Freeze the task unless there is a vfork - * completion pending - */ - if (!p->vfork_done) - freeze_process(p); - } else { - if (freeze_user_space) - continue; - - freeze_process(p); - } - todo++; + if (is_user_space(p) == !freeze_user_space) + continue; + + freeze_process(p); + if (!freezer_should_skip(p)) + todo++; } while_each_thread(g, p); read_unlock(&tasklist_lock); yield(); /* Yield is okay here */ @@ -161,7 +151,8 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space) continue; task_lock(p); - if (freezeable(p) && !frozen(p)) + if (freezeable(p) && !frozen(p) && + !freezer_should_skip(p)) printk(KERN_ERR " %s\n", p->comm); cancel_freezing(p); @@ -210,9 +201,7 @@ static void thaw_tasks(int thaw_user_space) if (is_user_space(p) == !thaw_user_space) continue; - if (!thaw_process(p)) - printk(KERN_WARNING " Strange, %s not stopped\n", - p->comm ); + thaw_process(p); } while_each_thread(g, p); read_unlock(&tasklist_lock); } -- cgit v1.2.3-59-g8ed1b