Re: [PATCH 04/13] livepatch: move klp_find_object_module to module.c

From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Andrew Donnellan <ajd@linux.ibm.com>,
	linux-kbuild@vger.kernel.org, David Airlie <airlied@linux.ie>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Jiri Kosina <jikos@kernel.org>,
	linux-kernel@vger.kernel.org, live-patching@vger.kernel.org,
	Michal Marek <michal.lkml@markovi.net>,
	dri-devel@lists.freedesktop.org,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Jessica Yu <jeyu@kernel.org>,
	Frederic Barrat <fbarrat@linux.ibm.com>,
	Miroslav Benes <mbenes@suse.cz>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 04/13] livepatch: move klp_find_object_module to module.c
Date: Thu, 21 Jan 2021 15:45:29 -0600	[thread overview]
Message-ID: <20210121214529.il2ac3vk6oqogjpr@treble> (raw)
In-Reply-To: <20210121074959.313333-5-hch@lst.de>

On Thu, Jan 21, 2021 at 08:49:50AM +0100, Christoph Hellwig wrote:
> @@ -820,14 +796,25 @@ static int klp_init_object(struct klp_patch *patch, struct klp_object *obj)
>  	const char *name;
>  
>  	obj->patched = false;
> -	obj->mod = NULL;

Why was this line removed?

>  	if (klp_is_module(obj)) {
>  		if (strlen(obj->name) >= MODULE_NAME_LEN)
>  			return -EINVAL;
>  		name = obj->name;
>  
> -		klp_find_object_module(obj);
> +		/*
> +		 * We do not want to block removal of patched modules and
> +		 * therefore we do not take a reference here. The patches are
> +		 * removed by klp_module_going() instead.
> +		 * 
> +		 * Do not mess work of klp_module_coming() and
> +		 * klp_module_going().  Note that the patch might still be
> +		 * needed before klp_module_going() is called.  Module functions
> +		 * can be called even in the GOING state until mod->exit()
> +		 * finishes.  This is especially important for patches that
> +		 * modify semantic of the functions.
> +		 */
> +		obj->mod = find_klp_module(obj->name);

These comments don't make sense in this context, they should be kept
with the code in find_klp_module().

-- 
Josh

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