RE: [PATCH] pinctrl: core: Make p->state in order in pinctrl_commit_state

["Aiqun Yu (Maria)" <aiquny@xxxxxxxxxxxxxxxx>]

Thx Greg,

Pls ignore this thread. Already correct to the normal  linux-kernel@xxxxxxxxxxxxxxx  in another email thread.

Thx and BRs,
Aiqun Yu (Maria)

-----Original Message-----
From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> 
Sent: Thursday, October 27, 2022 3:24 PM
To: Aiqun Yu (QUIC) <quic_aiquny@xxxxxxxxxxx>
Cc: linus.walleij@xxxxxxxxxx; linux-gpio@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] pinctrl: core: Make p->state in order in pinctrl_commit_state

WARNING: This email originated from outside of Qualcomm. Please be wary of any links or attachments, and do not enable macros.

On Thu, Oct 27, 2022 at 02:51:10PM +0800, Maria Yu wrote:
> We've got a dump that current cpu is in pinctrl_commit_state, the 
> old_state != p->state while the stack is still in the process of 
> pinmux_disable_setting. So it means even if the current p->state is 
> changed in new state, the settings are not yet up-to-date enabled 
> complete yet.
>
> Currently p->state in different value to synchronize the 
> pinctrl_commit_state behaviors. The p->state will have transaction 
> like old_state -> NULL -> new_state. When in old_state, it will try to 
> disable all the all state settings. And when after new state settings 
> enabled, p->state will changed to the new state after that. So use 
> smp_mb to synchronize the p->state variable and the settings in order.
> ---
>  drivers/pinctrl/core.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c index 
> 9e57f4c62e60..cd917a5b1a0a 100644
> --- a/drivers/pinctrl/core.c
> +++ b/drivers/pinctrl/core.c
> @@ -1256,6 +1256,7 @@ static int pinctrl_commit_state(struct pinctrl *p, struct pinctrl_state *state)
>               }
>       }
>
> +     smp_mb();
>       p->state = NULL;
>
>       /* Apply all the settings for the new state - pinmux first */ @@ 
> -1305,6 +1306,7 @@ static int pinctrl_commit_state(struct pinctrl *p, struct pinctrl_state *state)
>                       pinctrl_link_add(setting->pctldev, p->dev);
>       }
>
> +     smp_mb();
>       p->state = state;
>
>       return 0;
> --
> 2.17.1
>

<formletter>

This is not the correct way to submit patches for inclusion in the stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>