linux-kernel - [PATCH] Documentation: RCU: update the stall warning message "timer=-1" to match reality

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Message-ID: <alpine.DEB.2.00.1209211610280.30239@utopia.booyaka.com>
Date:	Fri, 21 Sep 2012 16:13:29 +0000 (UTC)
From:	Paul Walmsley <paul@...an.com>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Dipankar Sarma <dipankar@...ibm.com>
cc:	linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
	"Bruce, Becky" <bbruce@...com>, "Hilman, Kevin" <khilman@...com>,
	"Shilimkar, Santosh" <santosh.shilimkar@...com>,
	"Hunter, Jon" <jon-hunter@...com>, snijsure@...d-net.com
Subject: [PATCH] Documentation: RCU: update the stall warning message "timer=-1"
 to match reality


The CONFIG_RCU_FAST_NO_HZ stall warning messages can never emit
"timer=-1".  This is because the printf() format specifier to generate
that number is '%lu'.  So, update the documentation to use the
unsigned long equivalent instead, "timer=4294967295".  This is what
actually shows up in traces.

Signed-off-by: Paul Walmsley <paul@...an.com>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Dipankar Sarma <dipankar@...ibm.com>
---
 Documentation/RCU/stallwarn.txt |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt
index 523364e..fe3379e 100644
--- a/Documentation/RCU/stallwarn.txt
+++ b/Documentation/RCU/stallwarn.txt
@@ -99,7 +99,7 @@ In kernels with CONFIG_RCU_FAST_NO_HZ, even more information is
 printed:
 
 	INFO: rcu_preempt detected stall on CPU
-	0: (64628 ticks this GP) idle=dd5/3fffffffffffffff/0 drain=0 . timer=-1
+	0: (64628 ticks this GP) idle=dd5/3fffffffffffffff/0 drain=0 . timer=4294967295
 	   (t=65000 jiffies)
 
 The "(64628 ticks this GP)" indicates that this CPU has taken more
@@ -119,10 +119,10 @@ number (as shown above) otherwise.
 For CONFIG_RCU_FAST_NO_HZ kernels, the "drain=0" indicates that the
 CPU is not in the process of trying to force itself into dyntick-idle
 state, the "." indicates that the CPU has not given up forcing RCU
-into dyntick-idle mode (it would be "H" otherwise), and the "timer=-1"
-indicates that the CPU has not recented forced RCU into dyntick-idle
-mode (it would otherwise indicate the number of microseconds remaining
-in this forced state).
+into dyntick-idle mode (it would be "H" otherwise), and the
+"timer=4294967295" (the magic number (2^32)-1) indicates that the CPU
+has not recently forced RCU into dyntick-idle mode (it would otherwise
+indicate the number of microseconds remaining in this forced state).
 
 
 Multiple Warnings From One Stall
-- 
1.7.10.4

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