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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-01-13 10:52:35 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2016-03-31 13:34:03 -0700
commit251c617c75f48e03523c43c4ce1dff44bc3ae2bd (patch)
tree62be528b88376633dbb9c6d85aacf59948678aa5 /kernel/rcu
parent28728dd310d48834cd486dac3cac9ae96b9deb96 (diff)
downloadlinux-sh-251c617c75f48e03523c43c4ce1dff44bc3ae2bd.tar.gz
rcu: Make expedited RCU-preempt stall warnings count accurately
Currently, synchronize_sched_expedited_wait() simply sets the ndetected variable to the rcu_print_task_exp_stall() return value. This means that if the last rcu_node structure has no stalled tasks, record of any stalled tasks in previous rcu_node structures is lost, which can in turn result in failure to dump out the blocking rcu_node structures. Or could, had the test been correct. This commit therefore adds the return value of rcu_print_task_exp_stall() to ndetected and corrects the later test for ndetected. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 5f4336fadc28..687d8a5f35c7 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3778,7 +3778,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
rsp->name);
ndetected = 0;
rcu_for_each_leaf_node(rsp, rnp) {
- ndetected = rcu_print_task_exp_stall(rnp);
+ ndetected += rcu_print_task_exp_stall(rnp);
mask = 1;
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
struct rcu_data *rdp;
@@ -3797,7 +3797,7 @@ static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
pr_cont(" } %lu jiffies s: %lu root: %#lx/%c\n",
jiffies - jiffies_start, rsp->expedited_sequence,
rnp_root->expmask, ".T"[!!rnp_root->exp_tasks]);
- if (!ndetected) {
+ if (ndetected) {
pr_err("blocking rcu_node structures:");
rcu_for_each_node_breadth_first(rsp, rnp) {
if (rnp == rnp_root)