linux-kernel - Re: [PATCH] Revert "usb: typec: ucsi: add a common function ucsi_unregister

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Date:   Tue, 23 Aug 2022 10:22:50 +0300
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linyu Yuan <quic_linyyuan@...cinc.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Revert "usb: typec: ucsi: add a common function
 ucsi_unregister_connectors()"

On Tue, Aug 23, 2022 at 08:54:55AM +0200, Takashi Iwai wrote:
> The recent commit 87d0e2f41b8c ("usb: typec: ucsi: add a common
> function ucsi_unregister_connectors()") introduced a regression that
> caused NULL dereference at reading the power supply sysfs.  It's a
> stale sysfs entry that should have been removed but remains with NULL
> ops.  The commit changed the error handling to skip the entries after
> a NULL con->wq, and this leaves the power device unreleased.
> 
> For addressing the regression, the straight revert is applied here.
> Further code improvements can be done from the scratch again.
> 
> Fixes: 87d0e2f41b8c ("usb: typec: ucsi: add a common function ucsi_unregister_connectors()")
> Link: https://bugzilla.suse.com/show_bug.cgi?id=1202386
> Link: https://lore.kernel.org/r/87r11cmbx0.wl-tiwai@suse.de
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Takashi Iwai <tiwai@...e.de>

Acked-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

> ---
>  drivers/usb/typec/ucsi/ucsi.c | 53 ++++++++++++++++-------------------
>  1 file changed, 24 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> index 1aea46493b85..7f2624f42724 100644
> --- a/drivers/usb/typec/ucsi/ucsi.c
> +++ b/drivers/usb/typec/ucsi/ucsi.c
> @@ -1200,32 +1200,6 @@ static int ucsi_register_port(struct ucsi *ucsi, int index)
>  	return ret;
>  }
>  
> -static void ucsi_unregister_connectors(struct ucsi *ucsi)
> -{
> -	struct ucsi_connector *con;
> -	int i;
> -
> -	if (!ucsi->connector)
> -		return;
> -
> -	for (i = 0; i < ucsi->cap.num_connectors; i++) {
> -		con = &ucsi->connector[i];
> -
> -		if (!con->wq)
> -			break;
> -
> -		cancel_work_sync(&con->work);
> -		ucsi_unregister_partner(con);
> -		ucsi_unregister_altmodes(con, UCSI_RECIPIENT_CON);
> -		ucsi_unregister_port_psy(con);
> -		destroy_workqueue(con->wq);
> -		typec_unregister_port(con->port);
> -	}
> -
> -	kfree(ucsi->connector);
> -	ucsi->connector = NULL;
> -}
> -
>  /**
>   * ucsi_init - Initialize UCSI interface
>   * @ucsi: UCSI to be initialized
> @@ -1234,6 +1208,7 @@ static void ucsi_unregister_connectors(struct ucsi *ucsi)
>   */
>  static int ucsi_init(struct ucsi *ucsi)
>  {
> +	struct ucsi_connector *con;
>  	u64 command;
>  	int ret;
>  	int i;
> @@ -1264,7 +1239,7 @@ static int ucsi_init(struct ucsi *ucsi)
>  	}
>  
>  	/* Allocate the connectors. Released in ucsi_unregister() */
> -	ucsi->connector = kcalloc(ucsi->cap.num_connectors,
> +	ucsi->connector = kcalloc(ucsi->cap.num_connectors + 1,
>  				  sizeof(*ucsi->connector), GFP_KERNEL);
>  	if (!ucsi->connector) {
>  		ret = -ENOMEM;
> @@ -1288,7 +1263,15 @@ static int ucsi_init(struct ucsi *ucsi)
>  	return 0;
>  
>  err_unregister:
> -	ucsi_unregister_connectors(ucsi);
> +	for (con = ucsi->connector; con->port; con++) {
> +		ucsi_unregister_partner(con);
> +		ucsi_unregister_altmodes(con, UCSI_RECIPIENT_CON);
> +		ucsi_unregister_port_psy(con);
> +		if (con->wq)
> +			destroy_workqueue(con->wq);
> +		typec_unregister_port(con->port);
> +		con->port = NULL;
> +	}
>  
>  err_reset:
>  	memset(&ucsi->cap, 0, sizeof(ucsi->cap));
> @@ -1402,6 +1385,7 @@ EXPORT_SYMBOL_GPL(ucsi_register);
>  void ucsi_unregister(struct ucsi *ucsi)
>  {
>  	u64 cmd = UCSI_SET_NOTIFICATION_ENABLE;
> +	int i;
>  
>  	/* Make sure that we are not in the middle of driver initialization */
>  	cancel_delayed_work_sync(&ucsi->work);
> @@ -1409,7 +1393,18 @@ void ucsi_unregister(struct ucsi *ucsi)
>  	/* Disable notifications */
>  	ucsi->ops->async_write(ucsi, UCSI_CONTROL, &cmd, sizeof(cmd));
>  
> -	ucsi_unregister_connectors(ucsi);
> +	for (i = 0; i < ucsi->cap.num_connectors; i++) {
> +		cancel_work_sync(&ucsi->connector[i].work);
> +		ucsi_unregister_partner(&ucsi->connector[i]);
> +		ucsi_unregister_altmodes(&ucsi->connector[i],
> +					 UCSI_RECIPIENT_CON);
> +		ucsi_unregister_port_psy(&ucsi->connector[i]);
> +		if (ucsi->connector[i].wq)
> +			destroy_workqueue(ucsi->connector[i].wq);
> +		typec_unregister_port(ucsi->connector[i].port);
> +	}
> +
> +	kfree(ucsi->connector);
>  }
>  EXPORT_SYMBOL_GPL(ucsi_unregister);
>  
> -- 
> 2.35.3

thanks,

-- 
heikki