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040a0a3710
Wound/wait mutexes are used when other multiple lock acquisitions of a similar type can be done in an arbitrary order. The deadlock handling used here is called wait/wound in the RDBMS literature: The older tasks waits until it can acquire the contended lock. The younger tasks needs to back off and drop all the locks it is currently holding, i.e. the younger task is wounded. For full documentation please read Documentation/ww-mutex-design.txt. References: https://lwn.net/Articles/548909/ Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Rob Clark <robdclark@gmail.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: rostedt@goodmis.org Cc: daniel@ffwll.ch Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/51C8038C.9000106@canonical.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
49 lines
1.2 KiB
C
49 lines
1.2 KiB
C
/*
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* lib/debug_locks.c
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*
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* Generic place for common debugging facilities for various locks:
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* spinlocks, rwlocks, mutexes and rwsems.
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*
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* Started by Ingo Molnar:
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*
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* Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*/
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#include <linux/rwsem.h>
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#include <linux/mutex.h>
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#include <linux/export.h>
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#include <linux/spinlock.h>
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#include <linux/debug_locks.h>
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/*
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* We want to turn all lock-debugging facilities on/off at once,
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* via a global flag. The reason is that once a single bug has been
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* detected and reported, there might be cascade of followup bugs
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* that would just muddy the log. So we report the first one and
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* shut up after that.
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*/
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int debug_locks = 1;
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EXPORT_SYMBOL_GPL(debug_locks);
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/*
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* The locking-testsuite uses <debug_locks_silent> to get a
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* 'silent failure': nothing is printed to the console when
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* a locking bug is detected.
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*/
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int debug_locks_silent;
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EXPORT_SYMBOL_GPL(debug_locks_silent);
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/*
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* Generic 'turn off all lock debugging' function:
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*/
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int debug_locks_off(void)
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{
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if (__debug_locks_off()) {
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if (!debug_locks_silent) {
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console_verbose();
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return 1;
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}
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(debug_locks_off);
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