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Message-ID: <20140306174531.GA30634@midget.suse.cz> Date: Thu, 6 Mar 2014 18:45:31 +0100 From: Jiri Bohac <jbohac@...e.cz> To: John Stultz <john.stultz@...aro.org>, linux-kernel@...r.kernel.org Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl> Subject: is printk() safe within a timekeeper_seq write section? Hi, I'm looking at the printk call in __timekeeping_inject_sleeptime(), introduced in cb5de2f8 (time: Catch invalid timespec sleep values in __timekeeping_inject_sleeptime) Is it safe to call printk() while timekeeper_seq is held for writing? What about this call chain? printk vprintk_emit console_unlock up(&console_sem) __up wake_up_process try_to_wake_up ttwu_do_activate ttwu_activate activate_task enqueue_task enqueue_task_fair hrtick_update hrtick_start_fair hrtick_start_fair get_time ktime_get --> endless loop on read_seqcount_retry(&timekeeper_seq, ...) It looks like an unlikely but possible deadlock. Or did I overlook something? Thanks! -- Jiri Bohac <jbohac@...e.cz> SUSE Labs, SUSE CZ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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