rcu: Report error for bad rcu_nocbs= parameter values (497e4260) · Commits · 戴 / test

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@linux.ibm.com>

kernel/rcu/tree_plugin.h

+10 −2

Original line number	Diff line number	Diff line
		@@ -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);

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