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authorMiroslav Benes <mbenes@suse.cz>2014-12-22 11:10:12 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-01-15 23:33:16 -0800
commitec1fe396ff42e240c9b32111ee53665c5916fe5e (patch)
treeb9199fa245a072d9428e16d7faf24ae84246271a /kernel/rcu
parentfb81a44b88e6173ed0f6e9d6a1afa5305fb63f6e (diff)
downloadop-kernel-dev-ec1fe396ff42e240c9b32111ee53665c5916fe5e.zip
op-kernel-dev-ec1fe396ff42e240c9b32111ee53665c5916fe5e.tar.gz
rcu: Fix RCU CPU stall detection in tiny implementation
The tiny RCU CPU stall detection depends on *rcp->curtail not being NULL. It is however a tail pointer and thus NULL by definition. Instead we should check rcp->rcucblist for the presence of pending callbacks which need to be processed. With this fix INFO about the stall is printed and jiffies_stall (jiffies at next stall) correctly updated. Note that the check for pending callback is necessary to avoid spurious warnings if there are no pendings callbacks. Signed-off-by: Miroslav Benes <mbenes@suse.cz> [ paulmck: Fused identical "if" statements, ported to -rcu. ] Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tiny_plugin.h7
1 files changed, 3 insertions, 4 deletions
diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h
index 858c565..80f908a 100644
--- a/kernel/rcu/tiny_plugin.h
+++ b/kernel/rcu/tiny_plugin.h
@@ -145,17 +145,16 @@ static void check_cpu_stall(struct rcu_ctrlblk *rcp)
rcp->ticks_this_gp++;
j = jiffies;
js = ACCESS_ONCE(rcp->jiffies_stall);
- if (*rcp->curtail && ULONG_CMP_GE(j, js)) {
+ if (rcp->rcucblist && ULONG_CMP_GE(j, js)) {
pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n",
rcp->name, rcp->ticks_this_gp, rcu_dynticks_nesting,
jiffies - rcp->gp_start, rcp->qlen);
dump_stack();
- }
- if (*rcp->curtail && ULONG_CMP_GE(j, js))
ACCESS_ONCE(rcp->jiffies_stall) = jiffies +
3 * rcu_jiffies_till_stall_check() + 3;
- else if (ULONG_CMP_GE(j, js))
+ } else if (ULONG_CMP_GE(j, js)) {
ACCESS_ONCE(rcp->jiffies_stall) = jiffies + rcu_jiffies_till_stall_check();
+ }
}
static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp)
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