From e66c33d579ea566d10e8c8695a7168aae3e02992 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Fri, 12 Jul 2013 16:50:28 -0400 Subject: rcu: Add const annotation to char * for RCU tracepoints and functions All the RCU tracepoints and functions that reference char pointers do so with just 'char *' even though they do not modify the contents of the string itself. This will cause warnings if a const char * is used in one of these functions. The RCU tracepoints store the pointer to the string to refer back to them when the trace output is displayed. As this can be minutes, hours or even days later, those strings had better be constant. This change also opens the door to allow the RCU tracepoint strings and their addresses to be exported so that userspace tracing tools can translate the contents of the pointers of the RCU tracepoints. Signed-off-by: Steven Rostedt --- kernel/rcupdate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/rcupdate.c') diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index cce6ba8bbac..14994d4e1a5 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -377,7 +377,7 @@ EXPORT_SYMBOL_GPL(rcuhead_debug_descr); #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ #if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU) || defined(CONFIG_RCU_TRACE) -void do_trace_rcu_torture_read(char *rcutorturename, struct rcu_head *rhp, +void do_trace_rcu_torture_read(const char *rcutorturename, struct rcu_head *rhp, unsigned long secs, unsigned long c_old, unsigned long c) { -- cgit v1.2.3-70-g09d2 From 15100df81fcc3109862f7c03266c0abff4262564 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Tue, 23 Apr 2013 11:31:50 -0700 Subject: rcu: Simplify debug-objects fixups The current debug-objects fixups are complex and heavyweight, and the fixups are not complete: Even with the fixups, RCU's callback lists can still be corrupted. This commit therefore strips the fixups down to their minimal form, eliminating two of the three. It would be even better if (for example) call_rcu() simply leaked any problematic callbacks, but for that to happen, the debug-objects system would need to inform its caller of suspicious situations. This is the subject of a later commit in this series. Signed-off-by: Paul E. McKenney Cc: Mathieu Desnoyers Cc: Sedat Dilek Cc: Davidlohr Bueso Cc: Rik van Riel Cc: Thomas Gleixner Cc: Linus Torvalds Tested-by: Sedat Dilek Reviewed-by: Josh Triplett --- kernel/rcupdate.c | 100 ------------------------------------------------------ 1 file changed, 100 deletions(-) (limited to 'kernel/rcupdate.c') diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 14994d4e1a5..33eb4620aa1 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -211,43 +211,6 @@ static inline void debug_rcu_head_free(struct rcu_head *head) debug_object_free(head, &rcuhead_debug_descr); } -/* - * fixup_init is called when: - * - an active object is initialized - */ -static int rcuhead_fixup_init(void *addr, enum debug_obj_state state) -{ - struct rcu_head *head = addr; - - switch (state) { - case ODEBUG_STATE_ACTIVE: - /* - * 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_ONCE(1); - return 0; -#endif - if (rcu_preempt_depth() != 0 || preempt_count() != 0 || - irqs_disabled()) { - WARN_ON_ONCE(1); - return 0; - } - rcu_barrier(); - rcu_barrier_sched(); - rcu_barrier_bh(); - debug_object_init(head, &rcuhead_debug_descr); - return 1; - default: - return 0; - } -} - /* * fixup_activate is called when: * - an active object is activated @@ -268,69 +231,8 @@ static int rcuhead_fixup_activate(void *addr, enum debug_obj_state state) debug_object_init(head, &rcuhead_debug_descr); debug_object_activate(head, &rcuhead_debug_descr); return 0; - - case ODEBUG_STATE_ACTIVE: - /* - * 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_ONCE(1); - return 0; -#endif - if (rcu_preempt_depth() != 0 || preempt_count() != 0 || - irqs_disabled()) { - WARN_ON_ONCE(1); - return 0; - } - rcu_barrier(); - rcu_barrier_sched(); - rcu_barrier_bh(); - debug_object_activate(head, &rcuhead_debug_descr); - return 1; default: - return 0; - } -} - -/* - * fixup_free is called when: - * - an active object is freed - */ -static int rcuhead_fixup_free(void *addr, enum debug_obj_state state) -{ - struct rcu_head *head = addr; - - switch (state) { - case ODEBUG_STATE_ACTIVE: - /* - * 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_ONCE(1); - return 0; -#endif - if (rcu_preempt_depth() != 0 || preempt_count() != 0 || - irqs_disabled()) { - WARN_ON_ONCE(1); - return 0; - } - rcu_barrier(); - rcu_barrier_sched(); - rcu_barrier_bh(); - debug_object_free(head, &rcuhead_debug_descr); return 1; - default: - return 0; } } @@ -369,9 +271,7 @@ EXPORT_SYMBOL_GPL(destroy_rcu_head_on_stack); struct debug_obj_descr rcuhead_debug_descr = { .name = "rcu_head", - .fixup_init = rcuhead_fixup_init, .fixup_activate = rcuhead_fixup_activate, - .fixup_free = rcuhead_fixup_free, }; EXPORT_SYMBOL_GPL(rcuhead_debug_descr); #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */ -- cgit v1.2.3-70-g09d2