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

[Greg KH <gregkh@linuxfoundation.org>]

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>