watchdog: Improve initialisation error message and documentation

The error message 'NMI watchdog failed to create perf event...' does not make it clear that this is a fatal error for the watchdog. It also currently prints the error value as a pointer, rather than extracting the error code with PTR_ERR(). Fix that. Add a note to the description of the 'nowatchdog' kernel parameter to associate it with this message. Reported-by: Cesare Leonardi <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Don Zickus <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: <[email protected]> # .37.x and later LKML-Reference: <1294009362.3167.126.camel@localhost> Signed-off-by: Ingo Molnar <[email protected]>
hanmiltonxing · Jan 3, 2011 · 5514237 · 5514237
1 parent b518a64
commit 5514237
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diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
@@ -1759,7 +1759,7 @@ and is between 256 and 4096 characters. It is defined in the file
 
 	nousb		[USB] Disable the USB subsystem
 
-	nowatchdog	[KNL] Disable the lockup detector.
+	nowatchdog	[KNL] Disable the lockup detector (NMI watchdog).
 
 	nowb		[ARM]
 

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
@@ -364,7 +364,8 @@ static int watchdog_nmi_enable(int cpu)
 		goto out_save;
 	}
 
-	printk(KERN_ERR "NMI watchdog failed to create perf event on cpu%i: %p\n", cpu, event);
+	printk(KERN_ERR "NMI watchdog disabled for cpu%i: unable to create perf event: %ld\n",
+	       cpu, PTR_ERR(event));
 	return PTR_ERR(event);
 
 	/* success path */