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

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Message-ID: <87eh0itdxw.fsf@rustcorp.com.au>
Date:	Mon, 28 Apr 2014 11:25:55 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Lucas De Marchi <lucas.de.marchi@...il.com>
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.

Lucas De Marchi <lucas.de.marchi@...il.com> writes:
> 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?

I think it's sufficient: distros will get this patch via stable.  kmod
updates can occur at a natural pace.

Thanks,
Rusty.


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