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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-04-13 15:54:22 -0400
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-05-02 17:48:27 -0400
commit9dd8fb16c36178df2066387d2abd44d8b4dca8c8 (patch)
tree330ac5704044c12bcc94ec6bf96dbb27d1057f5d /include
parent616c310e83b872024271c915c1b9ab505b9efad9 (diff)
rcu: Make exit_rcu() more precise and consolidate
When running preemptible RCU, if a task exits in an RCU read-side critical section having blocked within that same RCU read-side critical section, the task must be removed from the list of tasks blocking a grace period (perhaps the current grace period, perhaps the next grace period, depending on timing). The exit() path invokes exit_rcu() to do this cleanup. However, the current implementation of exit_rcu() needlessly does the cleanup even if the task did not block within the current RCU read-side critical section, which wastes time and needlessly increases the size of the state space. Fix this by only doing the cleanup if the current task is actually on the list of tasks blocking some grace period. While we are at it, consolidate the two identical exit_rcu() functions into a single function. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Linus Torvalds <torvalds@linux-foundation.org> Conflicts: kernel/rcupdate.c
Diffstat (limited to 'include')
-rw-r--r--include/linux/rcupdate.h1
-rw-r--r--include/linux/rcutiny.h5
-rw-r--r--include/linux/rcutree.h12
3 files changed, 1 insertions, 17 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index bbfe7854a6a6..29665a3b3ac5 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -191,6 +191,7 @@ extern void rcu_idle_enter(void);
191extern void rcu_idle_exit(void); 191extern void rcu_idle_exit(void);
192extern void rcu_irq_enter(void); 192extern void rcu_irq_enter(void);
193extern void rcu_irq_exit(void); 193extern void rcu_irq_exit(void);
194extern void exit_rcu(void);
194 195
195/** 196/**
196 * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers 197 * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 080b5bdda28e..adb5e5a38cae 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -87,10 +87,6 @@ static inline void kfree_call_rcu(struct rcu_head *head,
87 87
88#ifdef CONFIG_TINY_RCU 88#ifdef CONFIG_TINY_RCU
89 89
90static inline void exit_rcu(void)
91{
92}
93
94static inline int rcu_needs_cpu(int cpu) 90static inline int rcu_needs_cpu(int cpu)
95{ 91{
96 return 0; 92 return 0;
@@ -98,7 +94,6 @@ static inline int rcu_needs_cpu(int cpu)
98 94
99#else /* #ifdef CONFIG_TINY_RCU */ 95#else /* #ifdef CONFIG_TINY_RCU */
100 96
101extern void exit_rcu(void);
102int rcu_preempt_needs_cpu(void); 97int rcu_preempt_needs_cpu(void);
103 98
104static inline int rcu_needs_cpu(int cpu) 99static inline int rcu_needs_cpu(int cpu)
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index e8ee5dd0854c..782a8ab51bc1 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -45,18 +45,6 @@ static inline void rcu_virt_note_context_switch(int cpu)
45 rcu_note_context_switch(cpu); 45 rcu_note_context_switch(cpu);
46} 46}
47 47
48#ifdef CONFIG_TREE_PREEMPT_RCU
49
50extern void exit_rcu(void);
51
52#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */
53
54static inline void exit_rcu(void)
55{
56}
57
58#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
59
60extern void synchronize_rcu_bh(void); 48extern void synchronize_rcu_bh(void);
61extern void synchronize_sched_expedited(void); 49extern void synchronize_sched_expedited(void);
62extern void synchronize_rcu_expedited(void); 50extern void synchronize_rcu_expedited(void);