From d2cf0854d728c42524efc169edb3505de8c1a9dc Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Tue, 23 Nov 2021 01:37:07 +0100 Subject: rcu/nocb: Allow empty "rcu_nocbs" kernel parameter Allow the rcu_nocbs kernel parameter to be specified just by itself, without specifying any CPUs. This allows systems administrators to use "rcu_nocbs" to specify that none of the CPUs are to be offloaded at boot time, but than any of them may be offloaded at runtime via cpusets. In contrast, if the "rcu_nocbs" or "nohz_full" kernel parameters are not specified at all, then not only are none of the CPUs offloaded at boot, none of them can be offloaded at runtime, either. While in the area, modernize the description of the "rcuo" kthreads' naming scheme. Reviewed-by: Neeraj Upadhyay Signed-off-by: Frederic Weisbecker Cc: Boqun Feng Cc: Uladzislau Rezki Cc: Josh Triplett Cc: Joel Fernandes Tested-by: Juri Lelli Signed-off-by: Paul E. McKenney --- kernel/rcu/tree_nocb.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'kernel/rcu') diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index f580a6b2e74e..0c1802ce4764 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -66,14 +66,16 @@ static bool rcu_nocb_is_setup; static int __init rcu_nocb_setup(char *str) { alloc_bootmem_cpumask_var(&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); + if (*str == '=') { + if (cpulist_parse(++str, rcu_nocb_mask)) { + pr_warn("rcu_nocbs= bad CPU range, all CPUs set\n"); + cpumask_setall(rcu_nocb_mask); + } } rcu_nocb_is_setup = true; return 1; } -__setup("rcu_nocbs=", rcu_nocb_setup); +__setup("rcu_nocbs", rcu_nocb_setup); static int __init parse_rcu_nocb_poll(char *arg) { -- cgit v1.2.3