From a00eeede507c975087b7b8df8cf2c9f88ba285de Mon Sep 17 00:00:00 2001 From: Matt Redfearn Date: Fri, 4 Nov 2016 09:28:56 +0000 Subject: [PATCH] MIPS: SMP: Use a completion event to signal CPU up If a secondary CPU failed to start, for any reason, the CPU requesting the secondary to start would get stuck in the loop waiting for the secondary to be present in the cpu_callin_map. Rather than that, use a completion event to signal that the secondary CPU has started and is waiting to synchronise counters. Since the CPU presence will no longer be marked in cpu_callin_map, remove the redundant test from arch_cpu_idle_dead(). Signed-off-by: Matt Redfearn Cc: Maciej W. Rozycki Cc: Jiri Slaby Cc: Paul Gortmaker Cc: Chris Metcalf Cc: Thomas Gleixner Cc: Qais Yousef Cc: James Hogan Cc: Paul Burton Cc: Marcin Nowakowski Cc: Andrew Morton Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/14502/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/process.c | 4 +--- arch/mips/kernel/smp.c | 15 +++++++++------ 2 files changed, 10 insertions(+), 9 deletions(-) diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c index efa1df52c616..3da0161bdf84 100644 --- a/arch/mips/kernel/process.c +++ b/arch/mips/kernel/process.c @@ -50,9 +50,7 @@ #ifdef CONFIG_HOTPLUG_CPU void arch_cpu_idle_dead(void) { - /* What the heck is this check doing ? */ - if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map)) - play_dead(); + play_dead(); } #endif diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c index 7ebb1918e2ac..03daf9008124 100644 --- a/arch/mips/kernel/smp.c +++ b/arch/mips/kernel/smp.c @@ -68,6 +68,8 @@ EXPORT_SYMBOL(cpu_sibling_map); cpumask_t cpu_core_map[NR_CPUS] __read_mostly; EXPORT_SYMBOL(cpu_core_map); +static DECLARE_COMPLETION(cpu_running); + /* * A logcal cpu mask containing only one VPE per core to * reduce the number of IPIs on large MT systems. @@ -369,7 +371,7 @@ asmlinkage void start_secondary(void) cpumask_set_cpu(cpu, &cpu_coherent_mask); notify_cpu_starting(cpu); - cpumask_set_cpu(cpu, &cpu_callin_map); + complete(&cpu_running); synchronise_count_slave(cpu); set_cpu_online(cpu, true); @@ -430,7 +432,6 @@ void smp_prepare_boot_cpu(void) { set_cpu_possible(0, true); set_cpu_online(0, true); - cpumask_set_cpu(0, &cpu_callin_map); } int __cpu_up(unsigned int cpu, struct task_struct *tidle) @@ -438,11 +439,13 @@ int __cpu_up(unsigned int cpu, struct task_struct *tidle) mp_ops->boot_secondary(cpu, tidle); /* - * Trust is futile. We should really have timeouts ... + * We must check for timeout here, as the CPU will not be marked + * online until the counters are synchronised. */ - while (!cpumask_test_cpu(cpu, &cpu_callin_map)) { - udelay(100); - schedule(); + if (!wait_for_completion_timeout(&cpu_running, + msecs_to_jiffies(1000))) { + pr_crit("CPU%u: failed to start\n", cpu); + return -EIO; } synchronise_count_master(cpu); -- 2.30.2