linux-kernel - parse_args() is too unforgivable?

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Message-ID: <20150824183126.GA8388@redhat.com>
Date:	Mon, 24 Aug 2015 20:31:26 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Rusty Russell <rusty@...tcorp.com.au>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: parse_args() is too unforgivable?

On 08/24, Oleg Nesterov wrote:
>
> I booted the kernel with the additional patch below, and nothing bad has
> happened,

Until I tried reboot it once with "locktorture.verbose=true" paramater.
It didn't boot.

This is because parse_args() just aborts after it hits the error, so other
arguments at the same initcall level are simply ignored.

Fixed by the patch below, but I simply can't believe nobody hit this (imo)
bug before.

Why does parse_args() do this?? I simply can't understand why parse_args()
adds more random and hard-to-understand problems if one of the args ("=true"
in this particular case) is wrong.

Yes, the patch below is probably oversimplified / incomplete but imho the
current behaviour is confusing. At least I was greatly confused ;) At least
(I think) it makes sense to let the user know that the rest of command line
was probably ignored.

Oleg.
---

--- a/kernel/params.c
+++ b/kernel/params.c
@@ -220,19 +220,19 @@ char *parse_args(const char *doing,
 				doing, param);

 		switch (ret) {
+		case 0:
+			break;
 		case -ENOENT:
 			pr_err("%s: Unknown parameter `%s'\n", doing, param);
-			return ERR_PTR(ret);
+			break;
 		case -ENOSPC:
 			pr_err("%s: `%s' too large for parameter `%s'\n",
 			       doing, val ?: "", param);
-			return ERR_PTR(ret);
-		case 0:
 			break;
 		default:
 			pr_err("%s: `%s' invalid for parameter `%s'\n",
 			       doing, val ?: "", param);
-			return ERR_PTR(ret);
+			break;
 		}
 	}

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