+ Johannes (you should check MAINTAINERS; devcoredump has a specified
maintainer)
On Sun, May 22, 2022 at 10:29 PM Duoming Zhou <duoming@xxxxxxxxxx> 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:
>
> (Interrupt context)
> fw_dump_timer_fn
> mwifiex_upload_device_dump
> dev_coredumpv(..., GFP_KERNEL)
> dev_coredumpm()
> kzalloc(sizeof(*devcd), gfp); //may sleep
> dev_set_name
> kobject_set_name_vargs
> kvasprintf_const(GFP_KERNEL, ...); //may sleep
> kstrdup(s, GFP_KERNEL); //may sleep
I was only half paying attention to this patch earlier, but I realize
one source of my confusion: you're blaming the fix wrong. This piece
of code was only added for mwifiex's USB support; the SDIO/PCIe
support is totally fine, as we perform the dump from a worker, not a
timer. So, you have the Fixes tag wrong.
> In order to let dev_coredumpv support atomic contexts, this patch
> changes the gfp_t parameter of kvasprintf_const and kstrdup in
> kobject_set_name_vargs from GFP_KERNEL to GFP_ATOMIC. What's more,
> In order to mitigate bug, this patch changes the gfp_t parameter
> of dev_coredumpv from GFP_KERNEL to GFP_ATOMIC.
>
> Fixes: 57670ee882d4 ("mwifiex: device dump support via devcoredump framework")
That's wrong. Should be:
Fixes: f5ecd02a8b20 mwifiex: device dump support for usb interface
> Signed-off-by: Duoming Zhou <duoming@xxxxxxxxxx>
> ---
> Changes in v3:
> - Let dev_coredumpv support atomic contexts.
>
> drivers/net/wireless/marvell/mwifiex/main.c | 2 +-
> lib/kobject.c | 4 ++--
You almost definitely want to split this in two. One to fix
devcoredump to _really_ support the gfp arg (or else to drop it), and
one to start using it appropriately in mwifiex.
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c
> index ace7371c477..258906920a2 100644
> --- a/drivers/net/wireless/marvell/mwifiex/main.c
> +++ b/drivers/net/wireless/marvell/mwifiex/main.c
> @@ -1116,7 +1116,7 @@ void mwifiex_upload_device_dump(struct mwifiex_adapter *adapter)
> mwifiex_dbg(adapter, MSG,
> "== mwifiex dump information to /sys/class/devcoredump start\n");
> dev_coredumpv(adapter->dev, adapter->devdump_data, adapter->devdump_len,
> - GFP_KERNEL);
> + GFP_ATOMIC);
As noted above, PCIe and SDIO support is working just fine. Seems a
bit much to force it to be GFP_ATOMIC in those cases.
Maybe you also need a gfp arg for mwifiex_upload_device_dump()?
Brian
> mwifiex_dbg(adapter, MSG,
> "== mwifiex dump information to /sys/class/devcoredump end\n");
>
