Messages in this thread Patch in this message | | | From | Sergey Senozhatsky <> | Subject | [RFC][PATCHv2 1/8] printk: move printk_pending out of per-cpu | Date | Wed, 29 Mar 2017 18:25:04 +0900 |
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Do not keep `printk_pending' in per-CPU area. We set the following bits of printk_pending: a) PRINTK_PENDING_WAKEUP when we need to wakeup klogd b) PRINTK_PENDING_OUTPUT when there is a pending output from deferred printk and we need to call console_unlock().
So none of the bits control/represent a state of a particular CPU and, basically, they should be global instead.
Besides we will use `printk_pending' to control printk kthread, so this patch is also a preparation work.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Suggested-by: Petr Mladek <pmladek@suse.com> --- kernel/printk/printk.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 2984fb0f0257..2d07678e9ff9 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -401,6 +401,14 @@ DEFINE_RAW_SPINLOCK(logbuf_lock); printk_safe_exit_irqrestore(flags); \ } while (0) +/* + * Delayed printk version, for scheduler-internal messages: + */ +#define PRINTK_PENDING_WAKEUP 0x01 +#define PRINTK_PENDING_OUTPUT 0x02 + +static unsigned long printk_pending; + #ifdef CONFIG_PRINTK DECLARE_WAIT_QUEUE_HEAD(log_wait); /* the next printk record to read by syslog(READ) or /proc/kmsg */ @@ -2654,25 +2662,15 @@ static int __init printk_late_init(void) late_initcall(printk_late_init); #if defined CONFIG_PRINTK -/* - * Delayed printk version, for scheduler-internal messages: - */ -#define PRINTK_PENDING_WAKEUP 0x01 -#define PRINTK_PENDING_OUTPUT 0x02 - -static DEFINE_PER_CPU(int, printk_pending); - static void wake_up_klogd_work_func(struct irq_work *irq_work) { - int pending = __this_cpu_xchg(printk_pending, 0); - - if (pending & PRINTK_PENDING_OUTPUT) { + if (test_and_clear_bit(PRINTK_PENDING_OUTPUT, &printk_pending)) { /* If trylock fails, someone else is doing the printing */ if (console_trylock()) console_unlock(); } - if (pending & PRINTK_PENDING_WAKEUP) + if (test_and_clear_bit(PRINTK_PENDING_WAKEUP, &printk_pending)) wake_up_interruptible(&log_wait); } @@ -2685,7 +2683,7 @@ void wake_up_klogd(void) { preempt_disable(); if (waitqueue_active(&log_wait)) { - this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); + set_bit(PRINTK_PENDING_WAKEUP, &printk_pending); irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); } preempt_enable(); @@ -2701,7 +2699,7 @@ int printk_deferred(const char *fmt, ...) r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args); va_end(args); - __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); + set_bit(PRINTK_PENDING_OUTPUT, &printk_pending); irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); preempt_enable(); -- 2.12.2
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