Re: [PATCHv2] init/do_mounts: Add create_dev() failure log

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 26 May 2015 11:56:58 +0530 Vishnu Pratap Singh <vishnu.ps@samsung.com> wrote:

> if create_dev() function fails to create the root mount device (/dev/root),
> then it goes to panic as root device not found but there is no check/log
> present in case of failure, So i have added the log in case it fails to
> create the root device. It will help in debugging.
> 
> ...
>
> --- a/init/do_mounts.c
> +++ b/init/do_mounts.c
> @@ -532,7 +532,8 @@ void __init mount_root(void)
>  	}
>  #endif
>  #ifdef CONFIG_BLOCK
> -	create_dev("/dev/root", ROOT_DEV);
> +	if (create_dev("/dev/root", ROOT_DEV) < 0)
> +		pr_err("Failed to create %s device !\n", "/dev/root");

That's a pretty strange use of printk.

And KERN_EMERG seems more appropriate when this happens.

And we may as well let the poor user know why the mknod failed.

This?

--- a/init/do_mounts.c~init-do_mounts-add-create_dev-failure-log-fix
+++ a/init/do_mounts.c
@@ -533,9 +533,13 @@ void __init mount_root(void)
 	}
 #endif
 #ifdef CONFIG_BLOCK
-	if (create_dev("/dev/root", ROOT_DEV) < 0)
-		pr_err("Failed to create %s device !\n", "/dev/root");
-	mount_block_root("/dev/root", root_mountflags);
+	{
+		int err = create_dev("/dev/root", ROOT_DEV);
+
+		if (err < 0)
+			pr_emerg("Failed to create /dev/root: %d\n", err);
+		mount_block_root("/dev/root", root_mountflags);
+	}
 #endif
 }
 
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