Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1711793
| From | Sergey Senozhatsky <sergey.senozhatsky@gmail.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [RFC][PATCHv5 05/13] printk: enable printk offloading |
| Date | 2017-08-15 05:10 +0200 |
| Message-ID | <ueAoW-4hM-17@gated-at.bofh.it> (permalink) |
| References | <ueAff-3Y4-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Initialize kernel printing thread and make printk offloading
possible. By default `atomic_print_limit' is set to 0, so no
offloading will take place, unless requested by user.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
kernel/printk/printk.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 59 insertions(+)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 3a0e78812818..05165f008bc8 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2913,6 +2913,65 @@ static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
.flags = IRQ_WORK_LAZY,
};
+static int printk_kthread_func(void *data)
+{
+ while (1) {
+ set_current_state(TASK_INTERRUPTIBLE);
+ /*
+ * We must check `printk_emergency' as well, to let
+ * printk_emergency_begin() stop active `printk_kthread' at
+ * some point. Otherwise we can end up in a loop:
+ * - we bail out of console_unlock() because of
+ * printk_kthread_should_stop()
+ * and
+ * - don't schedule() and attempt to return back
+ * immediately to console_unlock() because we
+ * see PRINTK_PENDING_OUTPUT bit set.
+ */
+ if (!test_bit(PRINTK_PENDING_OUTPUT, &printk_pending) ||
+ atomic_read(&printk_emergency) != 0)
+ schedule();
+
+ __set_current_state(TASK_RUNNING);
+
+ /* We might have been woken for stop */
+ if (kthread_should_park())
+ kthread_parkme();
+
+ console_lock();
+ console_unlock();
+
+ /* We might have been blocked on console_sem */
+ if (kthread_should_park())
+ kthread_parkme();
+ }
+
+ return 0;
+}
+
+/*
+ * Init printk kthread at late_initcall stage, after core/arch/device/etc.
+ * initialization.
+ */
+static int __init init_printk_kthread(void)
+{
+ struct task_struct *thread;
+
+ if (!alloc_cpumask_var(&printk_offload_cpus, GFP_KERNEL))
+ return -ENOMEM;
+
+ thread = kthread_run(printk_kthread_func, NULL, "printk");
+ if (IS_ERR(thread)) {
+ pr_err("printk: unable to create printing thread\n");
+ free_cpumask_var(printk_offload_cpus);
+ return PTR_ERR(thread);
+ }
+
+ printk_kthread = thread;
+ return 0;
+}
+late_initcall(init_printk_kthread);
+
void wake_up_klogd(void)
{
preempt_disable();
--
2.14.1
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[RFC][PATCHv5 00/13] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:00 +0200
[RFC][PATCHv5 12/13] printk: do not cond_resched() when we can offload Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 10/13] printk: force printk_kthread to offload printing Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 04/13] printk: add enforce_emergency parameter Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 07/13] printk: register syscore notifier Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
Re: [RFC][PATCHv5 07/13] printk: register syscore notifier "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-08-15 14:10 +0200
Re: [RFC][PATCHv5 07/13] printk: register syscore notifier Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-08-16 09:00 +0200
Re: [RFC][PATCHv5 07/13] printk: register syscore notifier "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-08-16 15:10 +0200
[RFC][PATCHv5 11/13] printk: always offload printing from user-space processes Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 05/13] printk: enable printk offloading Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 01/13] printk: move printk_pending out of per-cpu Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 02/13] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 08/13] printk: set watchdog_thresh as maximum value for atomic_print_limit Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 03/13] printk: add sync printk_emergency API Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 09/13] printk: add auto-emergency enforcement mechanism Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 13/13] printk: move offloading logic to per-cpu Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
[RFC][PATCHv5 06/13] printk: register PM notifier Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2017-08-15 05:10 +0200
Re: [RFC][PATCHv5 06/13] printk: register PM notifier "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-08-15 14:00 +0200
Re: [RFC][PATCHv5 06/13] printk: register PM notifier Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-08-16 09:40 +0200
Re: [RFC][PATCHv5 06/13] printk: register PM notifier "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-08-16 15:10 +0200
Re: [RFC][PATCHv5 06/13] printk: register PM notifier Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-08-17 08:00 +0200
Re: [RFC][PATCHv5 06/13] printk: register PM notifier "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2017-08-17 18:00 +0200
Re: [RFC][PATCHv5 06/13] printk: register PM notifier Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-08-18 01:20 +0200
Re: [RFC][PATCHv5 00/13] printk: introduce printing kernel thread Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2017-08-23 10:40 +0200
csiph-web