Commit 2760f5a4 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Hans de Goede
Browse files

stop_machine: Add stop_core_cpuslocked() for per-core operations 



Hardware core level testing features require near simultaneous execution
of WRMSR instructions on all threads of a core to initiate a test.

Provide a customized cut down version of stop_machine_cpuslocked() that
just operates on the threads of a single core.

Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220506225410.1652287-4-tony.luck@intel.com


Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
parent db1af129

include/linux/stop_machine.h

+16 −0
Original line number Diff line number Diff line
@@ -124,6 +124,22 @@ int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus); 
 */

int stop_machine_cpuslocked(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus);



/**

 * stop_core_cpuslocked: - stop all threads on just one core

 * @cpu: any cpu in the targeted core

 * @fn: the function to run

 * @data: the data ptr for @fn()

 *

 * Same as above, but instead of every CPU, only the logical CPUs of a

 * single core are affected.

 *

 * Context: Must be called from within a cpus_read_lock() protected region.

 *

 * Return: 0 if all executions of @fn returned 0, any non zero return

 * value if any returned non zero.

 */

int stop_core_cpuslocked(unsigned int cpu, cpu_stop_fn_t fn, void *data);



int stop_machine_from_inactive_cpu(cpu_stop_fn_t fn, void *data,

				   const struct cpumask *cpus);

#else	/* CONFIG_SMP || CONFIG_HOTPLUG_CPU */

kernel/stop_machine.c

+21 −0
Original line number Diff line number Diff line
@@ -633,6 +633,27 @@ int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus) 
}

EXPORT_SYMBOL_GPL(stop_machine);



#ifdef CONFIG_SCHED_SMT

int stop_core_cpuslocked(unsigned int cpu, cpu_stop_fn_t fn, void *data)

{

	const struct cpumask *smt_mask = cpu_smt_mask(cpu);



	struct multi_stop_data msdata = {

		.fn = fn,

		.data = data,

		.num_threads = cpumask_weight(smt_mask),

		.active_cpus = smt_mask,

	};



	lockdep_assert_cpus_held();



	/* Set the initial state and stop all online cpus. */

	set_state(&msdata, MULTI_STOP_PREPARE);

	return stop_cpus(smt_mask, multi_cpu_stop, &msdata);

}

EXPORT_SYMBOL_GPL(stop_core_cpuslocked);

#endif



/**

 * stop_machine_from_inactive_cpu - stop_machine() from inactive CPU

 * @fn: the function to run