Messages in this thread | | | Date | Tue, 20 May 2014 09:43:56 +0900 (JST) | From | Thomas Gleixner <> | Subject | Re: [patch 2/2] rtmutex: Avoid pointless requeueing in the deadlock detection chain walk |
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On Thu, 15 May 2014, Steven Rostedt wrote: > On Wed, 14 May 2014 20:03:27 -0000 > Thomas Gleixner <tglx@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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