On Tue, Dec 04, 2018 at 10:31:16AM +0100, Peter Zijlstra wrote:

On Mon, Dec 03, 2018 at 11:40:00PM -0800, Alison Schofield wrote:

quoted

 static int mktme_program_system(struct mktme_key_program *key_program,
-				cpumask_var_t mktme_cpumask)
+				cpumask_var_t mktme_cpumask, int hotplug)
 {
 	struct mktme_hw_program_info info = {
 		.key_program = key_program,
 		.status = MKTME_PROG_SUCCESS,
 	};
-	get_online_cpus();
-	on_each_cpu_mask(mktme_cpumask, mktme_program_package, &info, 1);
-	put_online_cpus();
+
+	if (!hotplug) {
+		get_online_cpus();
+		on_each_cpu_mask(mktme_cpumask, mktme_program_package,
+				 &info, 1);
+		put_online_cpus();
+	} else {
+		on_each_cpu_mask(mktme_cpumask, mktme_program_package,
+				 &info, 1);
+	}
 
 	return info.status;
 }

That is pretty horrible; and I think easily avoided.

Agree it's ugly. Not sure we share the same reasoning. I realize that
the hotplug case is on the current cpu and so that whole
one_each_cpu_mask() call is not needed. mktme_program_package() can just
be called on the current cpu.

The ugliness that haunts me is that I wanted to reuse this code path,
and so I passed that 'hotplug' parameter along as a differentiator
between hotplug & 'typical' key programming. 
I'll rework this.