linux-kernel - Re: [PATCH] module: remove warning about waiting module removal.

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Message-ID: <CAKi4VALZ9or4yqTt1LgZgzv4aK+pqf6o+opw0peERFi27esteg@mail.gmail.com>
Date:	Thu, 24 Apr 2014 08:15:20 -0300
From:	Lucas De Marchi <lucas.de.marchi@...il.com>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Valerio Vanni <valerio.vanni@...ind.it>, Elliott@...abs.org,
	Robert <Elliott@...com>
Subject: Re: [PATCH] module: remove warning about waiting module removal.

Hi Rusty,

On Thu, Apr 24, 2014 at 3:24 AM, Rusty Russell <rusty@...tcorp.com.au> wrote:
> We remove the waiting module removal in commit 3f2b9c9cdf38 (September
> 2013), but it turns out that modprobe in kmod (< version 16) was
> asking for waiting module removal.  Noone noticed since modprobe would
> check for 0 usage immediately before trying to remove the module, and
> the race is unlikely.
>
> However, it means that anyone running old (but not ancient) kmod
> versions is hitting the printk designed to see if anyone was running
> "rmmod -w".  All reports so far have been false positives, so remove
> the warning.
>
> Fixes: 3f2b9c9cdf389e303b2273679af08aab5f153517
> Reported-by: Valerio Vanni <valerio.vanni@...ind.it>
> Cc: Elliott, Robert (Server Storage) <Elliott@...com>
> Cc: stable@...nel.org
> Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 11869408f79b..ae7821898bf2 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -815,9 +815,6 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
>                 return -EFAULT;
>         name[MODULE_NAME_LEN-1] = '\0';
>
> -       if (!(flags & O_NONBLOCK))
> -               pr_warn("waiting module removal not supported: please upgrade\n");
> -
>         if (mutex_lock_interruptible(&module_mutex) != 0)
>                 return -EINTR;
>

Ack.

If you are going to apply this, do you think it'd be still good to
patch kmod on distros, so at least modprobe -r uses O_NONBLOCK? Or
having this patch in kernel is sufficient?

-- 
Lucas De Marchi
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