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| author |   Miroslav Benes <mbenes@suse.cz> | 2014-12-22 11:10:12 -0800 |
|---|---|---|
| committer |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-01-15 23:33:16 -0800 |
| commit | ec1fe396ff42e240c9b32111ee53665c5916fe5e (patch) | |
| tree | b9199fa245a072d9428e16d7faf24ae84246271a | |
| parent | rcu: Add GP-kthread-starvation checks to CPU stall warnings (diff) | |
| download | linux-dev-ec1fe396ff42e240c9b32111ee53665c5916fe5e.tar.xz linux-dev-ec1fe396ff42e240c9b32111ee53665c5916fe5e.zip | |
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>
| -rw-r--r-- | kernel/rcu/tiny_plugin.h | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h index 858c56569127..80f908afe348 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) |