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 <[email protected]> --- 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
