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authorPaul E. McKenney <paul.mckenney@linaro.org>2010-11-29 21:56:39 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-05-05 23:16:54 -0700
commit12f5f524cafef3ab689929b118f2dfb8bf2be321 (patch)
tree639473556b6edf9b79e0a18d5ba58f80eea76519 /kernel/rcutree.h
parente59fb3120becfb36b22ddb8bd27d065d3cdca499 (diff)
rcu: merge TREE_PREEPT_RCU blocked_tasks[] lists
Combine the current TREE_PREEMPT_RCU ->blocked_tasks[] lists in the rcu_node structure into a single ->blkd_tasks list with ->gp_tasks and ->exp_tasks tail pointers. This is in preparation for RCU priority boosting, which will add a third dimension to the combinatorial explosion in the ->blocked_tasks[] case, but simply a third pointer in the new ->blkd_tasks case. Also update documentation to reflect blocked_tasks[] merge Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcutree.h')
-rw-r--r--kernel/rcutree.h21
1 files changed, 15 insertions, 6 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index bd891def3303..5a439c180e69 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -107,7 +107,7 @@ 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[] */
+ unsigned long expmask; /* Groups that have ->blkd_tasks */
/* elements that need to drain to allow the */
/* current expedited grace period to */
/* complete (only for TREE_PREEMPT_RCU). */
@@ -120,11 +120,20 @@ 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[4];
- /* Tasks blocked in RCU read-side critsect. */
- /* Grace period number (->gpnum) x blocked */
- /* by tasks on the (x & 0x1) element of the */
- /* blocked_tasks[] array. */
+ struct list_head blkd_tasks;
+ /* Tasks blocked in RCU read-side critical */
+ /* section. Tasks are placed at the head */
+ /* of this list and age towards the tail. */
+ struct list_head *gp_tasks;
+ /* Pointer to the first task blocking the */
+ /* current grace period, or NULL if there */
+ /* is no such task. */
+ struct list_head *exp_tasks;
+ /* Pointer to the first task blocking the */
+ /* current expedited grace period, or NULL */
+ /* if there is no such task. If there */
+ /* is no current expedited grace period, */
+ /* then there can cannot be any such task. */
} ____cacheline_internodealigned_in_smp;
/*

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