Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: [RFC][PATCH -mm 3/3] freezer: Fix problem with kthread_stop | Date | Mon, 23 Apr 2007 21:50:30 +0200 |
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Hi,
On Monday, 23 April 2007 12:40, Pavel Machek wrote: > Hi! > > > Fix the problem with kthread_stop() that causes the freezer to fail if a > > freezable thread is attempting to stop a frozen one and that may cause the > > freezer to fail if the thread being stopped is freezable and > > try_to_freeze_tasks() is running concurrently with kthread_stop(). > > Parse error.
OK, will fix.
> > Index: linux-2.6.21-rc6-mm1/kernel/kthread.c > > =================================================================== > > --- linux-2.6.21-rc6-mm1.orig/kernel/kthread.c 2007-04-09 15:23:48.000000000 +0200 > > +++ linux-2.6.21-rc6-mm1/kernel/kthread.c 2007-04-22 19:05:29.000000000 +0200 > > @@ -232,6 +233,14 @@ int kthread_stop(struct task_struct *k) > > > > /* Now set kthread_should_stop() to true, and wake it up. */ > > kthread_stop_info.k = k; > > + if (!freezer_should_exempt(current)) { > > + /* We are freezable, so we must make sure that the thread being > > + * stopped is not frozen and will not be frozen until it dies > > + */ > > + freezer_exempt(k); > > + if (frozen(k)) > > + clear_frozen_flag(k); > > + } > > wake_up_process(k); > > put_task_struct(k); > > > > Do we need to take some locks to access other process' flags? Or do > frozen_exempt() etc take enough locks, already?
After the previous patch we only use set_bit(), clear_bit() and test_bit() to access freezer_falgs, so no special locking is needed to protect them.
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