linux-kernel - Re: [PATCH v5 2/2] mwifiex: fix sleep in atomic context bugs caused by dev

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Message-ID: <75b1682.54b44.1813b8abc1f.Coremail.duoming@zju.edu.cn>
Date:   Tue, 7 Jun 2022 08:22:36 +0800 (GMT+08:00)
From:   duoming@....edu.cn
To:     "Brian Norris" <briannorris@...omium.org>
Cc:     linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        amitkarwar@...il.com, ganapathi017@...il.com,
        sharvari.harisangam@....com, huxinming820@...il.com,
        kvalo@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, netdev@...r.kernel.org,
        johannes@...solutions.net, gregkh@...uxfoundation.org,
        rafael@...nel.org
Subject: Re: [PATCH v5 2/2] mwifiex: fix sleep in atomic context bugs caused
 by dev_coredumpv

Hello,

On Mon, 6 Jun 2022 11:14:05 -0700 Brian wrote:

> On Fri, Jun 03, 2022 at 01:09:35PM +0800, Duoming Zhou wrote:
> > There are sleep in atomic context bugs when uploading device dump
> > data in mwifiex. The root cause is that dev_coredumpv could not
> > be used in atomic contexts, because it calls dev_set_name which
> > include operations that may sleep. The call tree shows execution
> > paths that could lead to bugs:
> ...
> > Fixes: f5ecd02a8b20 ("mwifiex: device dump support for usb interface")
> > Signed-off-by: Duoming Zhou <duoming@....edu.cn>
> > ---
> > Changes in v5:
> >   - Use delayed work to replace timer.
> > 
> >  drivers/net/wireless/marvell/mwifiex/init.c      | 10 ++++++----
> >  drivers/net/wireless/marvell/mwifiex/main.h      |  2 +-
> >  drivers/net/wireless/marvell/mwifiex/sta_event.c |  6 +++---
> >  3 files changed, 10 insertions(+), 8 deletions(-)
> 
> Looks great! Thanks for working on this.
> 
> Reviewed-by: Brian Norris <briannorris@...omium.org>
> 
> Some small nitpicks below, but they're definitely not critical.

Thank you for your time and approval!

> > diff --git a/drivers/net/wireless/marvell/mwifiex/init.c b/drivers/net/wireless/marvell/mwifiex/init.c
> > index 88c72d1827a..3713f3e323f 100644
> > --- a/drivers/net/wireless/marvell/mwifiex/init.c
> > +++ b/drivers/net/wireless/marvell/mwifiex/init.c
> > @@ -63,9 +63,11 @@ static void wakeup_timer_fn(struct timer_list *t)
> >  		adapter->if_ops.card_reset(adapter);
> >  }
> >  
> > -static void fw_dump_timer_fn(struct timer_list *t)
> > +static void fw_dump_work(struct work_struct *work)
> >  {
> > -	struct mwifiex_adapter *adapter = from_timer(adapter, t, devdump_timer);
> > +	struct mwifiex_adapter *adapter = container_of(work,
> > +					struct mwifiex_adapter,
> > +					devdump_work.work);
> 
> Super nitpicky: the hanging indent style seems a bit off. I typically
> see people try to align to the first character after the parenthesis,
> like:
> 
> 	struct mwifiex_adapter *adapter = container_of(work,
> 						       struct mwifiex_adapter,
> 						       devdump_work.work);
> 
> It's not a clearly-specified style rule I think, so I definitely
> wouldn't insist.
> 
> On the bright side: I think the clang-format rules (in .clang-format)
> are getting better, so one can make some formatting decisions via tools
> instead of opinion and close reading! Unfortunately, we probably can't
> do that extensively and automatically, because I doubt people will love
> all the reformatting because of all the existing inconsistent style.
> 
> Anyway, to cut to the chase: clang-format chooses moving to a new line:
> 
> 	struct mwifiex_adapter *adapter =
> 		container_of(work, struct mwifiex_adapter, devdump_work.work);
> 
> More info if you're interested:
> https://www.kernel.org/doc/html/latest/process/clang-format.html
> 
> >  
> >  	mwifiex_upload_device_dump(adapter);
> >  }

Thanks for your suggestions! I will use clang-format to adjust the format.

> > diff --git a/drivers/net/wireless/marvell/mwifiex/main.h b/drivers/net/wireless/marvell/mwifiex/main.h
> > index 332dd1c8db3..6530c6ee308 100644
> > --- a/drivers/net/wireless/marvell/mwifiex/main.h
> > +++ b/drivers/net/wireless/marvell/mwifiex/main.h
> > @@ -1055,7 +1055,7 @@ struct mwifiex_adapter {
> 
> Nitpick: main.h is probably missing a lot of #includes, but you could
> probably add <linux/workqueue.h> while you're at it.

I will add <linux/workqueue.h> in main.h.

> 
> >  	/* Device dump data/length */
> >  	void *devdump_data;
> >  	int devdump_len;
> > -	struct timer_list devdump_timer;
> > +	struct delayed_work devdump_work;
> >  
> >  	bool ignore_btcoex_events;
> >  };

Best regards,
Duoming Zhou