This commit prints a console message when cpulist_parse() reports a
bad list of CPUs, and sets all CPUs' bits in that case. The reason for
setting all CPUs' bits is that this is the safe(r) choice for real-time
workloads, which would normally be the ones using the rcu_nocbs= kernel
boot parameter. Either way, later RCU console log messages list the
actual set of CPUs whose RCU callbacks will be offloaded.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxx>
---
kernel/rcu/tree_plugin.h | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index ed4a6dabf31d..f0aeb7416dcc 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1772,14 +1772,22 @@ static void zero_cpu_stall_ticks(struct rcu_data *rdp)
*/
-/* Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters. */
+/*
+ * Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters.
+ * The string after the "rcu_nocbs=" is either "all" for all CPUs, or a
+ * comma-separated list of CPUs and/or CPU ranges. If an invalid list is
+ * given, a warning is emitted and all CPUs are offloaded.
+ */
static int __init rcu_nocb_setup(char *str)
{
alloc_bootmem_cpumask_var(&rcu_nocb_mask);
if (!strcasecmp(str, "all"))
cpumask_setall(rcu_nocb_mask);
else
- cpulist_parse(str, rcu_nocb_mask);
+ if (cpulist_parse(str, rcu_nocb_mask)) {
+ pr_warn("rcu_nocbs= bad CPU range, all CPUs set\n");
+ cpumask_setall(rcu_nocb_mask);
+ }
return 1;
}
__setup("rcu_nocbs=", rcu_nocb_setup);
--
2.17.1
