Messages in this thread | | | Date | Mon, 14 Mar 2016 17:17:13 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [RFC][PATCH v3 1/2] printk: Make printk() completely async |
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On (03/14/16 08:11), Jan Kara wrote: [..] > > + if (!sync_print) { > > + if (printk_thread && !in_panic) { > > + /* > > + * Wakeup the printing kthread and offload printing > > + * to a schedulable context. > > + */ > > + wake_up(&printing_wait); > > + } else if (in_sched) { > > + /* > > + * @in_sched messages may come too early, when we don't > > + * yet have @printk_thread. We can't print deferred > > + * messages directly, because this may deadlock, route > > + * them via IRQ context. > > + */ > > + __this_cpu_or(printk_pending, > > + PRINTK_PENDING_OUTPUT); > > + irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); > > You cannot call wake_up() from a scheduler context - i.e., if in_sched is > true, you have to use irq work unconditionally. You can wake up kthread > from irq work or just directly print the message there. Otherwise the patch > looks fine.
oh, thanks for catching this! you are right.
-ss
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