linux-kernel - Re: [PATCH] call_usermodehelper_setup() should use GFP

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Date:	Thu, 08 May 2008 19:38:17 +0900
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	kosaki.motohiro@...fujitsu.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Paul Menage <menage@...gle.com>,
	Jeremy Fitzhardinge <jeremy@...source.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: Re: [PATCH] call_usermodehelper_setup() should use GFP_KERNEL

Hi

Thanks good comment!

> > How many times do we have to make this mistake :(
> >
> > Only the caller knows what allocation mode the callee can use. 
> > call_usermodehelper_setup() should be extended to take a gfp_t argument.
> 
> Yeah, but making the caller need to know about the internal 
> implementation details of the callee (ie, whether it needs to allocate 
> memory or not) leads to pretty warty interfaces.  In this case, you 
> could push the gfp_t up to the call_usermodehelper_setup() level, but 
> pushing it any higher wouldn't make much sense.

No problem :)
almost caller doesn't call call_usermodehelper_setup() directly.

thus, call_usermodehelper_setup() chage is hided in call_usermodehelper().


----------------chunk of my current testing patch-----------------------------

@@ -68,8 +69,9 @@ static inline int
 call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait)
 {
 	struct subprocess_info *info;
+	gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
 
-	info = call_usermodehelper_setup(path, argv, envp);
+	info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
 	if (info == NULL)
 		return -ENOMEM;
 	return call_usermodehelper_exec(info, wait);



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