Messages in this thread Patch in this message | | | Date | Wed, 23 Feb 2011 10:13:19 -0500 | From | Mathieu Desnoyers <> | Subject | [PATCH] debug rcu head support !PREEMPT config |
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Remove DEBUG_RCU_HEAD dependency on PREEMPT config. Handle the unability to detect if within a RCU read-side critical section by never performing any attempt to recover from a failure situation in the fixup handlers. Just print the warnings.
This patch is only compile-tested.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> --- kernel/rcupdate.c | 17 +++++++++++++++++ lib/Kconfig.debug | 2 +- 2 files changed, 18 insertions(+), 1 deletion(-)
Index: linux-2.6-lttng/lib/Kconfig.debug =================================================================== --- linux-2.6-lttng.orig/lib/Kconfig.debug +++ linux-2.6-lttng/lib/Kconfig.debug @@ -313,7 +313,7 @@ config DEBUG_OBJECTS_WORK config DEBUG_OBJECTS_RCU_HEAD bool "Debug RCU callbacks objects" - depends on DEBUG_OBJECTS && PREEMPT + depends on DEBUG_OBJECTS help Enable this to turn on debugging of RCU list heads (call_rcu() usage). Index: linux-2.6-lttng/kernel/rcupdate.c =================================================================== --- linux-2.6-lttng.orig/kernel/rcupdate.c +++ linux-2.6-lttng/kernel/rcupdate.c @@ -142,7 +142,14 @@ static int rcuhead_fixup_init(void *addr * Ensure that queued callbacks are all executed. * If we detect that we are nested in a RCU read-side critical * section, we should simply fail, otherwise we would deadlock. + * In !PREEMPT configurations, there is no way to tell if we are + * in a RCU read-side critical section or not, so we never + * attempt any fixup and just print a warning. */ +#ifndef CONFIG_PREEMPT + WARN_ON(1); + return 0; +#endif if (rcu_preempt_depth() != 0 || preempt_count() != 0 || irqs_disabled()) { WARN_ON(1); @@ -184,7 +191,14 @@ static int rcuhead_fixup_activate(void * * Ensure that queued callbacks are all executed. * If we detect that we are nested in a RCU read-side critical * section, we should simply fail, otherwise we would deadlock. + * In !PREEMPT configurations, there is no way to tell if we are + * in a RCU read-side critical section or not, so we never + * attempt any fixup and just print a warning. */ +#ifndef CONFIG_PREEMPT + WARN_ON(1); + return 0; +#endif if (rcu_preempt_depth() != 0 || preempt_count() != 0 || irqs_disabled()) { WARN_ON(1); @@ -214,6 +228,9 @@ static int rcuhead_fixup_free(void *addr * Ensure that queued callbacks are all executed. * If we detect that we are nested in a RCU read-side critical * section, we should simply fail, otherwise we would deadlock. + * In !PREEMPT configurations, there is no way to tell if we are + * in a RCU read-side critical section or not, so we never + * attempt any fixup and just print a warning. */ #ifndef CONFIG_PREEMPT WARN_ON(1); -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com
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