Messages in this thread Patch in this message | | | From | Sergey Senozhatsky <> | Subject | [RFC][PATCHv6 07/12] printk: register syscore notifier | Date | Mon, 4 Dec 2017 22:48:20 +0900 |
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We need to switch to emergency printk mode in kernel_kexec(). One kernel_kexec() branch calls kernel_restart_prepare(), which updates `system_state', however, the other one, when user requested to ->preserve_context, does not and we are lacking the information in printk about kexec being executed. Register a syscore notifier so printk will be notified by syscore_suspend().
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> --- kernel/printk/printk.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index a427cee2aa00..372c71f69e8e 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -49,6 +49,7 @@ #include <linux/sched/debug.h> #include <linux/sched/task_stack.h> #include <linux/kthread.h> +#include <linux/syscore_ops.h> #include <linux/uaccess.h> #include <asm/sections.h> @@ -2914,6 +2915,22 @@ static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { .flags = IRQ_WORK_LAZY, }; +static int printk_syscore_suspend(void) +{ + printk_emergency_begin(); + return 0; +} + +static void printk_syscore_resume(void) +{ + printk_emergency_end(); +} + +static struct syscore_ops printk_syscore_ops = { + .suspend = printk_syscore_suspend, + .resume = printk_syscore_resume, +}; + static int printk_kthread_func(void *data) { while (1) { @@ -2961,6 +2978,8 @@ static int __init init_printk_kthread(void) if (!alloc_cpumask_var(&printk_offload_cpus, GFP_KERNEL)) return -ENOMEM; + register_syscore_ops(&printk_syscore_ops); + thread = kthread_run(printk_kthread_func, NULL, "printk"); if (IS_ERR(thread)) { pr_err("printk: unable to create printing thread\n"); -- 2.15.1
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