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SubjectRe: [PATCH v5 2/2] mwifiex: fix sleep in atomic context bugs caused by dev_coredumpv
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@zju.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@chromium.org>

Some small nitpicks below, but they're definitely not critical.

> 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);
> }

...

> 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.

Brian

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

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