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From c0d9702755192d191020f5e625b6e3d0c795262b Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Wed, 14 Dec 2011 13:05:54 +0100
Subject: [PATCH 195/274] rt: Improve the serial console PASS_LIMIT
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Beyond the warning:
drivers/tty/serial/8250/8250.c:1613:6: warning: unused variable ‘pass_counter’ [-Wunused-variable]
the solution of just looping infinitely was ugly - up it to 1 million to
give it a chance to continue in some really ugly situation.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
drivers/tty/serial/8250/8250.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/tty/serial/8250/8250.c b/drivers/tty/serial/8250/8250.c
index ff93c70..a785ec0 100644
--- a/drivers/tty/serial/8250/8250.c
+++ b/drivers/tty/serial/8250/8250.c
@@ -80,7 +80,16 @@ static unsigned int skip_txen_test; /* force skip of txen test at init time */
#define DEBUG_INTR(fmt...) do { } while (0)
#endif
-#define PASS_LIMIT 512
+/*
+ * On -rt we can have a more delays, and legitimately
+ * so - so don't drop work spuriously and spam the
+ * syslog:
+ */
+#ifdef CONFIG_PREEMPT_RT_FULL
+# define PASS_LIMIT 1000000
+#else
+# define PASS_LIMIT 512
+#endif
#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
@@ -1584,14 +1593,12 @@ static irqreturn_t serial8250_interrupt(int irq, void *dev_id)
l = l->next;
-#ifndef CONFIG_PREEMPT_RT_FULL
if (l == i->head && pass_counter++ > PASS_LIMIT) {
/* If we hit this, we're dead. */
printk_ratelimited(KERN_ERR
"serial8250: too much work for irq%d\n", irq);
break;
}
-#endif
} while (l != end);
spin_unlock(&i->lock);
--
1.7.10.4
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