On Thu, 15 May 2014, Steven Rostedt wrote:
> On Wed, 14 May 2014 20:03:27 -0000
> Thomas Gleixner <t...@linutronix.de> wrote:
>
> > In case the dead lock detector is enabled we follow the lock chain to
> > the end in rt_mutex_adjust_prio_chain, even if we could stop earlier
> > due to the priority/waiter constellation.
>
> I'm assuming that we want to detect deadlocks for all futex calls
> even when CONFIG_DEBUG_RT_MUTEXES is set?
>
> In kernel/locking/rtmutex_common.h:
>
> #ifdef CONFIG_DEBUG_RT_MUTEXES
> # include "rtmutex-debug.h"
> #else
> # include "rtmutex.h"
> #endif
>
> In kernel/locking/rtmutex.h:
>
> #define debug_rt_mutex_detect_deadlock(w,d) (d)
>
> In kernel/locking/rtmutex.h:
>
> static inline int debug_rt_mutex_detect_deadlock(struct rt_mutex_waiter
> *waiter,
> int detect)
> {
> return (waiter != NULL);
> }
>
> Shouldn't that be: return detect || waiter != NULL;
>
No. We do not care about whether the caller handed in detect or not.
>
> I know this a separate issue from this patch series, but it's
> something that I just noticed.
It's not really intuitive. We might make the call sites hand in
constants. RTMUTEX_DETECT_DEADLOCK, RTMUTEX_IGNORE_DEADLOCK or
something like that and switch it depending on
CONFIG_DEBUG_RT_MUTEXES.
Thanks,
tglx
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