Messages in this thread | | | Date | Mon, 2 Apr 2007 13:56:32 +0000 | From | Pavel Machek <> | Subject | Re: [PATCH 1/8] Enhance process freezer interface for usage beyond software suspend |
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Hi!
> This patch provides an interface to extend the use of the process > freezer beyond Suspend. > > The tasks can selectively mark themselves to be exempted from specific > freeze events like SUSPEND /KPROBES/CPU_HOTPLUG. > > This patch however, *does not* sort non freezable threads into > different categories based on the freeze events. Thus all > tasks which were previously marked PF_NOFREEZE are now > exempted from freezer using > freezer_exempt(FE_ALL); > which means exempt from all kinds of freezes. > > Signed-off-by: Gautham R Shenoy <ego@in.ibm.com> > Cc: Pavel Machek <pavel@ucw.cz> > Cc: Rafael J. Wysocki <rjw@sisk.pl> > Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Actually no, I was not in cc.
> +/* Per process freezer specific flags */ > +#define PF_FE_SUSPEND 0x00008000 /* This thread should not be frozen > + * for suspend > + */ > + > +#define PF_FE_KPROBES 0x00000010 /* This thread should not be frozen > + * for Kprobes > + */
Just put the comment before the define for long comments?
> -#ifdef CONFIG_PM > +#if defined(CONFIG_PM) || defined(CONFIG_HOTPLUG_CPU) || \ > + defined(CONFIG_KPROBES)
Should we create CONFIG_FREEZER?
> Index: linux-2.6.21-rc5/kernel/softlockup.c > =================================================================== > --- linux-2.6.21-rc5.orig/kernel/softlockup.c > +++ linux-2.6.21-rc5/kernel/softlockup.c > @@ -96,7 +96,7 @@ static int watchdog(void * __bind_cpu) > struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 }; > > sched_setscheduler(current, SCHED_FIFO, ¶m); > - current->flags |= PF_NOFREEZE; > + freezer_exempt(FE_ALL); > > /* > * Run briefly once per second to reset the softlockup timestamp.
Hmmm, I do not really like softlockup watchdog running during suspend. Can we make this freezeable and make watchdog shut itself off while suspending?
> Index: linux-2.6.21-rc5/kernel/rcutorture.c > =================================================================== > --- linux-2.6.21-rc5.orig/kernel/rcutorture.c > +++ linux-2.6.21-rc5/kernel/rcutorture.c > @@ -559,7 +559,7 @@ rcu_torture_fakewriter(void *arg) > > VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started"); > set_user_nice(current, 19); > - current->flags |= PF_NOFREEZE; > + freezer_exempt(FE_ALL);
Fix rcutorture instead. It has no business running while suspending.
> > do { > schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10); > @@ -590,7 +590,7 @@ rcu_torture_reader(void *arg) > > VERBOSE_PRINTK_STRING("rcu_torture_reader task started"); > set_user_nice(current, 19); > - current->flags |= PF_NOFREEZE; > + freezer_exempt(FE_ALL); >
Same here.
Eventually, we should fix apm, too.
> Index: linux-2.6.21-rc5/init/do_mounts_initrd.c > =================================================================== > --- linux-2.6.21-rc5.orig/init/do_mounts_initrd.c > +++ linux-2.6.21-rc5/init/do_mounts_initrd.c > @@ -55,7 +55,7 @@ static void __init handle_initrd(void) > sys_mount(".", "/", NULL, MS_MOVE, NULL); > sys_chroot("."); > > - current->flags |= PF_NOFREEZE; > + freezer_exempt(FE_ALL); > pid = kernel_thread(do_linuxrc, "/linuxrc", SIGCHLD); > if (pid > 0) { > while (pid != sys_wait4(-1, NULL, 0, NULL))
Does this mean we have userland /linuxrc running with PF_NOFREEZE? That would be very bad...
> --- linux-2.6.21-rc5.orig/kernel/kprobes.c > +++ linux-2.6.21-rc5/kernel/kprobes.c > @@ -104,7 +104,7 @@ static int __kprobes check_safety(void) > { > int ret = 0; > #if defined(CONFIG_PREEMPT) && defined(CONFIG_PM)
Eh? Why does kprobes code depend on config_pm?
Pavel
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