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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2009-12-02 12:10:15 -0800
committerIngo Molnar <mingo@elte.hu>2009-12-03 11:35:25 +0100
commitd9a3da0699b24a589b27a61e1a5b5bd30d9db669 (patch)
treef7440e396a6c818f3cef514ccc31ab55d88025ef /kernel/rcutree.h
parentcf244dc01bf68e1ad338b82447f8686d24ea4435 (diff)
rcu: Add expedited grace-period support for preemptible RCU
Implement an synchronize_rcu_expedited() for preemptible RCU that actually is expedited. This uses synchronize_sched_expedited() to force all threads currently running in a preemptible-RCU read-side critical section onto the appropriate ->blocked_tasks[] list, then takes a snapshot of all of these lists and waits for them to drain. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1259784616158-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcutree.h')
-rw-r--r--kernel/rcutree.h35
1 files changed, 32 insertions, 3 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index df2e0b694744..d2a0046f63b2 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -104,8 +104,12 @@ struct rcu_node {
/* an rcu_data structure, otherwise, each */
/* bit corresponds to a child rcu_node */
/* structure. */
+ unsigned long expmask; /* Groups that have ->blocked_tasks[] */
+ /* elements that need to drain to allow the */
+ /* current expedited grace period to */
+ /* complete (only for TREE_PREEMPT_RCU). */
unsigned long qsmaskinit;
- /* Per-GP initialization for qsmask. */
+ /* Per-GP initial value for qsmask & expmask. */
unsigned long grpmask; /* Mask to apply to parent qsmask. */
/* Only one bit will be set in this mask. */
int grplo; /* lowest-numbered CPU or group here. */
@@ -113,7 +117,7 @@ struct rcu_node {
u8 grpnum; /* CPU/group number for next level up. */
u8 level; /* root is at level 0. */
struct rcu_node *parent;
- struct list_head blocked_tasks[2];
+ struct list_head blocked_tasks[4];
/* Tasks blocked in RCU read-side critsect. */
/* Grace period number (->gpnum) x blocked */
/* by tasks on the (x & 0x1) element of the */
@@ -128,6 +132,21 @@ struct rcu_node {
for ((rnp) = &(rsp)->node[0]; \
(rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++)
+/*
+ * Do a breadth-first scan of the non-leaf rcu_node structures for the
+ * specified rcu_state structure. Note that if there is a singleton
+ * rcu_node tree with but one rcu_node structure, this loop is a no-op.
+ */
+#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
+ for ((rnp) = &(rsp)->node[0]; \
+ (rnp) < (rsp)->level[NUM_RCU_LVLS - 1]; (rnp)++)
+
+/*
+ * Scan the leaves of the rcu_node hierarchy for the specified rcu_state
+ * structure. Note that if there is a singleton rcu_node tree with but
+ * one rcu_node structure, this loop -will- visit the rcu_node structure.
+ * It is still a leaf node, even if it is also the root node.
+ */
#define rcu_for_each_leaf_node(rsp, rnp) \
for ((rnp) = (rsp)->level[NUM_RCU_LVLS - 1]; \
(rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++)
@@ -261,7 +280,7 @@ struct rcu_state {
long gpnum; /* Current gp number. */
long completed; /* # of last completed gp. */
- /* End of fields guarded by root rcu_node's lock. */
+ /* End of fields guarded by root rcu_node's lock. */
spinlock_t onofflock; /* exclude on/offline and */
/* starting new GP. Also */
@@ -293,6 +312,13 @@ struct rcu_state {
#endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */
};
+/* Return values for rcu_preempt_offline_tasks(). */
+
+#define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */
+ /* GP were moved to root. */
+#define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */
+ /* GP were moved to root. */
+
#ifdef RCU_TREE_NONCORE
/*
@@ -333,6 +359,9 @@ static void rcu_preempt_offline_cpu(int cpu);
static void rcu_preempt_check_callbacks(int cpu);
static void rcu_preempt_process_callbacks(void);
void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
+#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)
+static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp);
+#endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */
static int rcu_preempt_pending(int cpu);
static int rcu_preempt_needs_cpu(int cpu);
static void __cpuinit rcu_preempt_init_percpu_data(int cpu);

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