linux-kernel - Re: [PATCH 1/2] do_coredump: factor out put

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Date:	Fri, 26 Jun 2009 22:33:54 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Roland McGrath <roland@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Neil Horman <nhorman@...driver.com>,
	linux-kernel@...r.kernel.org, earl_chew@...lent.com,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH 1/2] do_coredump: factor out put_cred() calls

On 06/26, Roland McGrath wrote:
>
> >  	if (!binfmt || !binfmt->core_dump)
> > -		goto fail;
> > +		goto out;
> [...]
> > +out:
> >  	return;
> >  }
>
> If the label does nothing, just use "return" instead of goto.

But this is what the current code does, I just renamed "fail" to "out"
to make sure I didn't miss a goto.

And in fact I am not sure return is better, "goto out" looks more
consistent to me.

But OK, please find the updated patch below.

--------------------------------------------------------------------------
[PATCH 1/2] do_coredump: factor out put_cred() calls

Given that do_coredump() calls put_cred() on exit path, it is a bit ugly
to do put_cred() + "goto fail" twice, just add the new "fail_creds" label.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>

--- WAIT/fs/exec.c~CD_1_PUT_CRED	2009-06-15 12:48:28.000000000 +0200
+++ WAIT/fs/exec.c	2009-06-26 22:30:28.000000000 +0200
@@ -1732,13 +1732,11 @@ void do_coredump(long signr, int exit_co
 
 	binfmt = current->binfmt;
 	if (!binfmt || !binfmt->core_dump)
-		goto fail;
+		return;
 
 	cred = prepare_creds();
-	if (!cred) {
-		retval = -ENOMEM;
-		goto fail;
-	}
+	if (!cred)
+		return;
 
 	down_write(&mm->mmap_sem);
 	/*
@@ -1746,8 +1744,7 @@ void do_coredump(long signr, int exit_co
 	 */
 	if (mm->core_state || !get_dumpable(mm)) {
 		up_write(&mm->mmap_sem);
-		put_cred(cred);
-		goto fail;
+		goto fail_creds;
 	}
 
 	/*
@@ -1761,10 +1758,8 @@ void do_coredump(long signr, int exit_co
 	}
 
 	retval = coredump_wait(exit_code, &core_state);
-	if (retval < 0) {
-		put_cred(cred);
-		goto fail;
-	}
+	if (retval < 0)
+		goto fail_creds;
 
 	old_cred = override_creds(cred);
 
@@ -1862,9 +1857,8 @@ fail_unlock:
 	if (helper_argv)
 		argv_free(helper_argv);
 
+	coredump_finish(mm);
 	revert_creds(old_cred);
+fail_creds:
 	put_cred(cred);
-	coredump_finish(mm);
-fail:
-	return;
 }

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