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Unverified Commit 37a107ff authored by Andreas Schwab's avatar Andreas Schwab Committed by Palmer Dabbelt
Browse files

riscv: don't stop itself in smp_send_stop 



Add IPI_CPU_STOP message and use it in smp_send_stop to stop other cpus,
but not itself.  Mark cpu offline on reception of IPI_CPU_STOP.

Signed-off-by: default avatarAndreas Schwab <schwab@suse.de>
Reviewed-by: default avatarAtish Patra <atish.patra@wdc.com>
Signed-off-by: default avatarPalmer Dabbelt <palmer@sifive.com>
parent 8fd6e05c

arch/riscv/kernel/smp.c

+36 −7
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/smp.h>

#include <linux/sched.h>

#include <linux/seq_file.h>

#include <linux/delay.h>



#include <asm/sbi.h>

#include <asm/tlbflush.h>
@@ -31,6 +32,7 @@ 
enum ipi_message_type {

	IPI_RESCHEDULE,

	IPI_CALL_FUNC,

	IPI_CPU_STOP,

	IPI_MAX

};
@@ -66,6 +68,13 @@ int setup_profiling_timer(unsigned int multiplier) 
	return -EINVAL;

}



static void ipi_stop(void)

{

	set_cpu_online(smp_processor_id(), false);

	while (1)

		wait_for_interrupt();

}



void riscv_software_interrupt(void)

{

	unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
@@ -94,6 +103,11 @@ void riscv_software_interrupt(void) 
			generic_smp_call_function_interrupt();

		}



		if (ops & (1 << IPI_CPU_STOP)) {

			stats[IPI_CPU_STOP]++;

			ipi_stop();

		}



		BUG_ON((ops >> IPI_MAX) != 0);



		/* Order data access and bit testing. */
@@ -121,6 +135,7 @@ send_ipi_message(const struct cpumask *to_whom, enum ipi_message_type operation) 
static const char * const ipi_names[] = {

	[IPI_RESCHEDULE]	= "Rescheduling interrupts",

	[IPI_CALL_FUNC]		= "Function call interrupts",

	[IPI_CPU_STOP]		= "CPU stop interrupts",

};



void show_ipi_stats(struct seq_file *p, int prec)
@@ -146,15 +161,29 @@ void arch_send_call_function_single_ipi(int cpu) 
	send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC);

}



static void ipi_stop(void *unused)

void smp_send_stop(void)

{

	while (1)

		wait_for_interrupt();

	unsigned long timeout;



	if (num_online_cpus() > 1) {

		cpumask_t mask;



		cpumask_copy(&mask, cpu_online_mask);

		cpumask_clear_cpu(smp_processor_id(), &mask);



		if (system_state <= SYSTEM_RUNNING)

			pr_crit("SMP: stopping secondary CPUs\n");

		send_ipi_message(&mask, IPI_CPU_STOP);

	}



void smp_send_stop(void)

{

	on_each_cpu(ipi_stop, NULL, 1);

	/* Wait up to one second for other CPUs to stop */

	timeout = USEC_PER_SEC;

	while (num_online_cpus() > 1 && timeout--)

		udelay(1);



	if (num_online_cpus() > 1)

		pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",

			   cpumask_pr_args(cpu_online_mask));

}



void smp_send_reschedule(int cpu)