Re: [PATCH -rt 1/9] preempt rcu: check for underflow
On Mon, 2007-07-30 at 11:22 +0200, Ingo Molnar wrote: > * Daniel Walker <[EMAIL PROTECTED]> wrote: > > > + /* > > +* If our rcu_read_lock_nesting went negative, likely > > +* something is wrong.. > > +*/ > > + WARN_ON(current->rcu_read_lock_nesting < 0); > > have you actually caught any rcu locking problem this way? Double > unlocks should be caught by lockdep already, at a higher level. > > in any case i've added a slightly different form of this change to the > -rt queue that will also check for counter overflows. But i'm not sure > we want to litter the code with trivial checks like this, so i'm keeping > it separate and if it does not trigger anything real i'll remove it. I haven't caught anything with it, but this code would have made it much easier to catch the single rcu unlock in sys_sched_yield() which was silent in PREEMPT_RT, and hung !PREEMPT_RT .. It's fine with me, if you have another method. Daniel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -rt 1/9] preempt rcu: check for underflow
* Daniel Walker <[EMAIL PROTECTED]> wrote: > + /* > + * If our rcu_read_lock_nesting went negative, likely > + * something is wrong.. > + */ > + WARN_ON(current->rcu_read_lock_nesting < 0); have you actually caught any rcu locking problem this way? Double unlocks should be caught by lockdep already, at a higher level. in any case i've added a slightly different form of this change to the -rt queue that will also check for counter overflows. But i'm not sure we want to litter the code with trivial checks like this, so i'm keeping it separate and if it does not trigger anything real i'll remove it. Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -rt 1/9] preempt rcu: check for underflow
* Daniel Walker [EMAIL PROTECTED] wrote: + /* + * If our rcu_read_lock_nesting went negative, likely + * something is wrong.. + */ + WARN_ON(current-rcu_read_lock_nesting 0); have you actually caught any rcu locking problem this way? Double unlocks should be caught by lockdep already, at a higher level. in any case i've added a slightly different form of this change to the -rt queue that will also check for counter overflows. But i'm not sure we want to litter the code with trivial checks like this, so i'm keeping it separate and if it does not trigger anything real i'll remove it. Ingo - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -rt 1/9] preempt rcu: check for underflow
On Mon, 2007-07-30 at 11:22 +0200, Ingo Molnar wrote: * Daniel Walker [EMAIL PROTECTED] wrote: + /* +* If our rcu_read_lock_nesting went negative, likely +* something is wrong.. +*/ + WARN_ON(current-rcu_read_lock_nesting 0); have you actually caught any rcu locking problem this way? Double unlocks should be caught by lockdep already, at a higher level. in any case i've added a slightly different form of this change to the -rt queue that will also check for counter overflows. But i'm not sure we want to litter the code with trivial checks like this, so i'm keeping it separate and if it does not trigger anything real i'll remove it. I haven't caught anything with it, but this code would have made it much easier to catch the single rcu unlock in sys_sched_yield() which was silent in PREEMPT_RT, and hung !PREEMPT_RT .. It's fine with me, if you have another method. Daniel - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -rt 1/9] preempt rcu: check for underflow
On Sun, Jul 29, 2007 at 07:45:35PM -0700, Daniel Walker wrote: > Simple WARN_ON to catch any underflow in rcu_read_lock_nesting. > > Signed-off-by: Daniel Walker <[EMAIL PROTECTED]> Acked-by: Paul E. McKenney <[EMAIL PROTECTED]> > --- > kernel/rcupreempt.c |6 ++ > 1 file changed, 6 insertions(+) > > Index: linux-2.6.22/kernel/rcupreempt.c > === > --- linux-2.6.22.orig/kernel/rcupreempt.c > +++ linux-2.6.22/kernel/rcupreempt.c > @@ -157,6 +157,12 @@ void __rcu_read_unlock(void) > } > > local_irq_restore(oldirq); > + > + /* > + * If our rcu_read_lock_nesting went negative, likely > + * something is wrong.. > + */ > + WARN_ON(current->rcu_read_lock_nesting < 0); > } > > static void __rcu_advance_callbacks(void) > > -- > - > To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH -rt 1/9] preempt rcu: check for underflow
Simple WARN_ON to catch any underflow in rcu_read_lock_nesting. Signed-off-by: Daniel Walker <[EMAIL PROTECTED]> --- kernel/rcupreempt.c |6 ++ 1 file changed, 6 insertions(+) Index: linux-2.6.22/kernel/rcupreempt.c === --- linux-2.6.22.orig/kernel/rcupreempt.c +++ linux-2.6.22/kernel/rcupreempt.c @@ -157,6 +157,12 @@ void __rcu_read_unlock(void) } local_irq_restore(oldirq); + + /* +* If our rcu_read_lock_nesting went negative, likely +* something is wrong.. +*/ + WARN_ON(current->rcu_read_lock_nesting < 0); } static void __rcu_advance_callbacks(void) -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH -rt 1/9] preempt rcu: check for underflow
Simple WARN_ON to catch any underflow in rcu_read_lock_nesting. Signed-off-by: Daniel Walker [EMAIL PROTECTED] --- kernel/rcupreempt.c |6 ++ 1 file changed, 6 insertions(+) Index: linux-2.6.22/kernel/rcupreempt.c === --- linux-2.6.22.orig/kernel/rcupreempt.c +++ linux-2.6.22/kernel/rcupreempt.c @@ -157,6 +157,12 @@ void __rcu_read_unlock(void) } local_irq_restore(oldirq); + + /* +* If our rcu_read_lock_nesting went negative, likely +* something is wrong.. +*/ + WARN_ON(current-rcu_read_lock_nesting 0); } static void __rcu_advance_callbacks(void) -- - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH -rt 1/9] preempt rcu: check for underflow
On Sun, Jul 29, 2007 at 07:45:35PM -0700, Daniel Walker wrote: Simple WARN_ON to catch any underflow in rcu_read_lock_nesting. Signed-off-by: Daniel Walker [EMAIL PROTECTED] Acked-by: Paul E. McKenney [EMAIL PROTECTED] --- kernel/rcupreempt.c |6 ++ 1 file changed, 6 insertions(+) Index: linux-2.6.22/kernel/rcupreempt.c === --- linux-2.6.22.orig/kernel/rcupreempt.c +++ linux-2.6.22/kernel/rcupreempt.c @@ -157,6 +157,12 @@ void __rcu_read_unlock(void) } local_irq_restore(oldirq); + + /* + * If our rcu_read_lock_nesting went negative, likely + * something is wrong.. + */ + WARN_ON(current-rcu_read_lock_nesting 0); } static void __rcu_advance_callbacks(void) -- - To unsubscribe from this list: send the line unsubscribe linux-rt-users in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
