linux-kernel - Re: [PATCH] firmware class: remove from pending list on load failure

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Date:	Thu, 8 Jan 2015 11:06:47 +0800
From:	Ming Lei <ming.lei@...onical.com>
To:	Sasha Levin <sasha.levin@...cle.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] firmware class: remove from pending list on load failure

On Thu, Jan 8, 2015 at 10:37 AM, Sasha Levin <sasha.levin@...cle.com> wrote:
> On 01/07/2015 09:15 PM, Ming Lei wrote:
>> On Thu, Jan 8, 2015 at 12:39 AM, Sasha Levin <sasha.levin@...cle.com> wrote:
>>> On 01/06/2015 11:52 PM, Ming Lei wrote:
>>>> On Mon, Jan 5, 2015 at 11:41 PM, Sasha Levin <sasha.levin@...cle.com> wrote:
>>>>>> If we failed loading the firmware we have to make sure it leaves the pending
>>>>>> list if abort wasn't executed for it.
>>>>>>
>>>>>> Otherwise we'd free an object still on the pending list and corrupt it.
>>>>>>
>>>>>> Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
>>>>>> ---
>>>>>>  drivers/base/firmware_class.c | 11 ++++++++++-
>>>>>>  1 file changed, 10 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
>>>>>> index 58470c3..8ccf6cf4 100644
>>>>>> --- a/drivers/base/firmware_class.c
>>>>>> +++ b/drivers/base/firmware_class.c
>>>>>> @@ -929,9 +929,18 @@ static int _request_firmware_load(struct firmware_priv *fw_priv,
>>>>>>         cancel_delayed_work_sync(&fw_priv->timeout_work);
>>>>>>         if (is_fw_load_aborted(buf))
>>>>>>                 retval = -EAGAIN;
>>>>>> -       else if (!buf->data)
>>>>>> +       else if (!buf->data) {
>>>>>>                 retval = -ENOMEM;
>>>>>>
>>>>>> +               /*
>>>>>> +                * We failed loading, but abort was never done so we
>>>>>> +                * need to remove it from the pending list ourselves.
>>>>>> +                */
>>>>>> +               mutex_lock(&fw_lock);
>>>>>> +               list_del_init(&buf->pending_list);
>>>>>> +               mutex_unlock(&fw_lock);
>>>> The buf is always removed before the complete_all(), isn't it? Or did
>>>> you observe the issue?
>>>
>>> Not in the case where userspacehelper fails. Yes, this is not a theoretical
>>> thing and can be easily reproduced.
>>
>> OK, I am just curious how it is triggered.
>>
>> One situation I thought of is that the request context is interrupted
>> by signal after wait_for_completion() becomes interruptable, and the
>> fix should abort the request if retval is -ERESTARTSYS.
>>
>> Or could you share how to reproduce if it isn't above case?
>
> It's pretty simple, just abort it once with Ctrl-C:

Looks it is just the case I said, :-)

Then I suggest you to remove the buf from list in case of
'retval == -ERESTARTSYS', and the return value should be
changed to -EINTR.


Thanks,
Ming Lei
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