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

From: Ming Lei
Date: Wed Jan 07 2015 - 21:16:08 EST


On Thu, Jan 8, 2015 at 12:39 AM, Sasha Levin <sasha.levin@xxxxxxxxxx> wrote:
> On 01/06/2015 11:52 PM, Ming Lei wrote:
>> On Mon, Jan 5, 2015 at 11:41 PM, Sasha Levin <sasha.levin@xxxxxxxxxx> 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@xxxxxxxxxx>
>>> > ---
>>> > 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?

Thanks,
Ming Lei
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/