[KJ] [PATCH][RESEND] misc_register : arch/x86_64/kernel/mce.c

[KJ] [PATCH][RESEND] misc_register : arch/x86_64/kernel/mce.c

[Christophe Lucas]

Description:
Audit return codes (and handle failure correctly) for misc_register.

Signed-off-by: Christophe Lucas <clucas@rotomalug.org>


Index: linux-2.6.18/arch/x86_64/kernel/mce.c
=================================--- linux-2.6.18.orig/arch/x86_64/kernel/mce.c	2006-10-02 13:57:17.000000000 +0200
+++ linux-2.6.18/arch/x86_64/kernel/mce.c	2006-10-02 13:57:58.000000000 +0200
@@ -663,7 +663,9 @@
 	}
 
 	register_hotcpu_notifier(&mce_cpu_notifier);
-	misc_register(&mce_log_device);
+	err = misc_register(&mce_log_device);
+	if (err < 0)
+		printk(KERN_ERR "Failed to register mce.\n");
 	return err;
 }
 
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Re: [KJ] [PATCH][RESEND] misc_register : arch/x86_64/kernel/mce.c

[Amol Lad]

> -	misc_register(&mce_log_device);
> +	err = misc_register(&mce_log_device);
> +	if (err < 0)
> +		printk(KERN_ERR "Failed to register mce.\n");
>  	return err;

Failure of misc_register not necessarily means that the calling function
should return an error. There are two possible cases:
1. Programmer deliberately left of misc_register return check as he
thought the error is not critical. Here you may want to just print a
warning message. (like arch/i386/kernel/apm.c)
2. Bug. This is where you need to return error.

Now the challenge is to differentiate between 1 & 2.

Good luck

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