From: Andreas Schwab <schwab@suse.de>
To: Atish Patra <atish.patra@wdc.com>
Cc: "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>
Subject: [PATCH v2] riscv: don't stop itself in smp_send_stop
Date: Tue, 11 Dec 2018 11:20:40 +0100 [thread overview]
Message-ID: <mvmd0q89xfr.fsf_-_@suse.de> (raw)
In-Reply-To: <mvmsgz5bqd7.fsf@suse.de> (Andreas Schwab's message of "Mon, 10 Dec 2018 11:58:12 +0100")
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: Andreas Schwab <schwab@suse.de>
---
arch/riscv/kernel/smp.c | 43 ++++++++++++++++++++++++++++++++++-------
1 file changed, 36 insertions(+), 7 deletions(-)
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index 57b1383e5e..b813264416 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -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)
-{
- while (1)
- wait_for_interrupt();
-}
-
void smp_send_stop(void)
{
- on_each_cpu(ipi_stop, NULL, 1);
+ 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);
+ }
+
+ /* 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_warning("SMP: failed to stop secondary CPUs %*pbl\n",
+ cpumask_pr_args(cpu_online_mask));
}
void smp_send_reschedule(int cpu)
--
2.20.0
--
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."
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next prev parent reply other threads:[~2018-12-11 10:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-29 16:32 [PATCH] riscv: don't stop itself in smp_send_stop Andreas Schwab
2018-11-29 18:52 ` Atish Patra
2018-12-10 10:58 ` Andreas Schwab
2018-12-11 0:06 ` Atish Patra
2018-12-11 10:20 ` Andreas Schwab [this message]
2018-12-13 23:27 ` [PATCH v2] " Atish Patra
2019-01-03 19:22 ` Palmer Dabbelt
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