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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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220506225410.1652287-4-tony.luck@intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
This commit is contained in:
Peter Zijlstra 2022-05-06 15:54:01 -07:00 committed by Hans de Goede
parent db1af12929
commit 2760f5a415
2 changed files with 37 additions and 0 deletions
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16
include/linux/stop_machine.h
View File

@ -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 */

21
kernel/stop_machine.c
View File

@ -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