can: dev: add sanity check in can_set_static_ctrlmode()

Previous patch removed can_priv::ctrlmode_static to replace it with
can_get_static_ctrlmode().

A condition sine qua non for this to work is that the controller
static modes should never be set in can_priv::ctrlmode_supported
(c.f. the comment on can_priv::ctrlmode_supported which states that it
is for "options that can be *modified* by netlink"). Also, this
condition is already correctly fulfilled by all existing drivers
which rely on the ctrlmode_static feature.

Nonetheless, we added an extra safeguard in can_set_static_ctrlmode()
to return an error value and to warn the developer who would be
adventurous enough to set to static a given feature that is already
set to supported.

The drivers which rely on the static controller mode are then updated
to check the return value of can_set_static_ctrlmode().

Link: https://lore.kernel.org/all/20211213160226.56219-3-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index ae23494..5b47cd8 100644 (file)
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1456,7 +1456,7 @@ static bool m_can_niso_supported(struct m_can_classdev *cdev)
 static int m_can_dev_setup(struct m_can_classdev *cdev)
 {
        struct net_device *dev = cdev->net;
-       int m_can_version;
+       int m_can_version, err;
 
        m_can_version = m_can_check_core_release(cdev);
        /* return if unsupported version */
@@ -1486,7 +1486,9 @@ static int m_can_dev_setup(struct m_can_classdev *cdev)
        switch (cdev->version) {
        case 30:
                /* CAN_CTRLMODE_FD_NON_ISO is fixed with M_CAN IP v3.0.x */
-               can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD_NON_ISO);
+               err = can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD_NON_ISO);
+               if (err)
+                       return err;
                cdev->can.bittiming_const = cdev->bit_timing ?
                        cdev->bit_timing : &m_can_bittiming_const_30X;
 
@@ -1496,7 +1498,9 @@ static int m_can_dev_setup(struct m_can_classdev *cdev)
                break;
        case 31:
                /* CAN_CTRLMODE_FD_NON_ISO is fixed with M_CAN IP v3.1.x */
-               can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD_NON_ISO);
+               err = can_set_static_ctrlmode(dev, CAN_CTRLMODE_FD_NON_ISO);
+               if (err)
+                       return err;
                cdev->can.bittiming_const = cdev->bit_timing ?
                        cdev->bit_timing : &m_can_bittiming_const_31X;
 

diff --git a/drivers/net/can/rcar/rcar_canfd.c b/drivers/net/can/rcar/rcar_canfd.c
index d0e795f..82cc71d 100644 (file)
--- a/drivers/net/can/rcar/rcar_canfd.c
+++ b/drivers/net/can/rcar/rcar_canfd.c
@@ -1699,7 +1699,9 @@ static int rcar_canfd_channel_probe(struct rcar_canfd_global *gpriv, u32 ch,
                        &rcar_canfd_data_bittiming_const;
 
                /* Controller starts in CAN FD only mode */
-               can_set_static_ctrlmode(ndev, CAN_CTRLMODE_FD);
+               err = can_set_static_ctrlmode(ndev, CAN_CTRLMODE_FD);
+               if (err)
+                       goto fail;
                priv->can.ctrlmode_supported = CAN_CTRLMODE_BERR_REPORTING;
        } else {
                /* Controller starts in Classical CAN only mode */

diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 92e2d69..fff3f70 100644 (file)
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -131,17 +131,24 @@ static inline s32 can_get_relative_tdco(const struct can_priv *priv)
 }
 
 /* helper to define static CAN controller features at device creation time */
-static inline void can_set_static_ctrlmode(struct net_device *dev,
-                                          u32 static_mode)
+static inline int __must_check can_set_static_ctrlmode(struct net_device *dev,
+                                                      u32 static_mode)
 {
        struct can_priv *priv = netdev_priv(dev);
 
        /* alloc_candev() succeeded => netdev_priv() is valid at this point */
+       if (priv->ctrlmode_supported & static_mode) {
+               netdev_warn(dev,
+                           "Controller features can not be supported and static at the same time\n");
+               return -EINVAL;
+       }
        priv->ctrlmode = static_mode;
 
        /* override MTU which was set by default in can_setup()? */
        if (static_mode & CAN_CTRLMODE_FD)
                dev->mtu = CANFD_MTU;
+
+       return 0;
 }
 
 static inline u32 can_get_static_ctrlmode(struct can_priv *priv)