From 578d36f5e160208821e8f51037ac1038e065ecaf Mon Sep 17 00:00:00 2001 From: Yi Li Date: Wed, 2 Dec 2009 07:58:12 +0000 Subject: [PATCH] Blackfin: SMP: don't start up core b until its state has been completely onlined When testing PREEMPT_RT kernel on BF561-EZKit, the kernel blocks while booting. When the kernel initializes the ethernet driver, it sleeps and never wakes up. The issue happens when the kernel waits for a timer for Core B to timeout (the timers are per-cpu based: static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases). However, the ksoftirqd thread for Core B (note, the ksoftirqd thread is also per-cpu based) cannot work properly, and the timers for Core B never times out. When ksoftirqd() for the first time runs on core B, it is possible core A is still initializing core B (see smp_init() -> cpu_up() -> __cpu_up()). So the "cpu_is_offline()" check may return true and ksoftirqd moves to "wait_to_die". So delay the core b start up until the per-cpu timers have been set up fully. Signed-off-by: Yi Li Signed-off-by: Mike Frysinger --- arch/blackfin/mach-bf561/smp.c | 17 +++++++---------- arch/blackfin/mach-common/smp.c | 16 ++++++++-------- 2 files changed, 15 insertions(+), 18 deletions(-) diff --git a/arch/blackfin/mach-bf561/smp.c b/arch/blackfin/mach-bf561/smp.c index 510f57641495..0192532e96a2 100644 --- a/arch/blackfin/mach-bf561/smp.c +++ b/arch/blackfin/mach-bf561/smp.c @@ -52,8 +52,6 @@ int __init setup_profiling_timer(unsigned int multiplier) /* not supported */ void __cpuinit platform_secondary_init(unsigned int cpu) { - local_irq_disable(); - /* Clone setup for peripheral interrupt sources from CoreA. */ bfin_write_SICB_IMASK0(bfin_read_SICA_IMASK0()); bfin_write_SICB_IMASK1(bfin_read_SICA_IMASK1()); @@ -70,11 +68,6 @@ void __cpuinit platform_secondary_init(unsigned int cpu) bfin_write_SICB_IAR7(bfin_read_SICA_IAR7()); SSYNC(); - local_irq_enable(); - - /* Calibrate loops per jiffy value. */ - calibrate_delay(); - /* Store CPU-private information to the cpu_data array. */ bfin_setup_cpudata(cpu); @@ -108,9 +101,13 @@ int __cpuinit platform_boot_secondary(unsigned int cpu, struct task_struct *idle barrier(); } - spin_unlock(&boot_lock); - - return cpu_isset(cpu, cpu_callin_map) ? 0 : -ENOSYS; + if (cpu_isset(cpu, cpu_callin_map)) { + cpu_set(cpu, cpu_online_map); + /* release the lock and let coreb run */ + spin_unlock(&boot_lock); + return 0; + } else + panic("CPU%u: processor failed to boot\n", cpu); } void __init platform_request_ipi(irq_handler_t handler) diff --git a/arch/blackfin/mach-common/smp.c b/arch/blackfin/mach-common/smp.c index d92b168c8328..369e687582b7 100644 --- a/arch/blackfin/mach-common/smp.c +++ b/arch/blackfin/mach-common/smp.c @@ -336,13 +336,6 @@ int __cpuinit __cpu_up(unsigned int cpu) ret = platform_boot_secondary(cpu, idle); - if (ret) { - cpu_clear(cpu, cpu_present_map); - printk(KERN_CRIT "CPU%u: processor failed to boot (%d)\n", cpu, ret); - free_task(idle); - } else - cpu_set(cpu, cpu_online_map); - secondary_stack = NULL; return ret; @@ -418,9 +411,16 @@ void __cpuinit secondary_start_kernel(void) setup_secondary(cpu); + platform_secondary_init(cpu); + local_irq_enable(); - platform_secondary_init(cpu); + /* + * Calibrate loops per jiffy value. + * IRQs need to be enabled here - D-cache can be invalidated + * in timer irq handler, so core B can read correct jiffies. + */ + calibrate_delay(); cpu_idle(); } -- 2.39.5