On Wed, 25 Jan 2017 15:08:45 +0100
Petr Mladek [off-list ref] wrote:
quoted hunk ↗ jump to hunk
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 7180088cbb23..cc90c0a5ae21 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2158,19 +2158,18 @@ void console_unlock(void)
}
/*
- * Console drivers are called under logbuf_lock, so
- * @console_may_schedule should be cleared before; however, we may
- * end up dumping a lot of lines, for example, if called from
- * console registration path, and should invoke cond_resched()
- * between lines if allowable. Not doing so can cause a very long
- * scheduling stall on a slow console leading to RCU stall and
- * softlockup warnings which exacerbate the issue with more
- * messages practically incapacitating the system.
Why did you remove the comment about invoking cond_resched()? It's
still pertinent to the code, as there still exists a:
if (do_cond_resched)
cond_resched();
And the rational in the comment is still correct.
-- Steve
quoted hunk ↗ jump to hunk
+ * Console drivers are called with interrupts disabled, so
+ * @console_may_schedule must be cleared before. The original
+ * value must be stored so that we could schedule between lines.
+ *
+ * console_trylock() is not able to detect the preemtible
+ * context reliably. Therefore the value must be stored before
+ * and cleared after the the "again" goto label.
*/
do_cond_resched = console_may_schedule;
+again:
console_may_schedule = 0;
-again:
/*
* We released the console_sem lock, so we need to recheck if
* cpu is online and (if not) is there at least one CON_ANYTIME