Re: [RFC PATCH net-next v3 05/20] net: dsa: qca8k: handle error with qca8k_read operation

Andrew Lunn
2021-05-05T00:36:23Z

On Wed, May 05, 2021 at 12:28:59AM +0200, Ansuel Smith wrote:
> qca8k_read can fail. Rework any user to handle error values and
> correctly return.
>
> Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> ---
> drivers/net/dsa/qca8k.c | 90 +++++++++++++++++++++++++++++++----------
> 1 file changed, 69 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
> index 411b42d38819..cde68ed6856b 100644
> --- a/drivers/net/dsa/qca8k.c
> +++ b/drivers/net/dsa/qca8k.c
> @@ -146,12 +146,13 @@ qca8k_set_page(struct mii_bus *bus, u16 page)
> static u32
> qca8k_read(struct qca8k_priv *priv, u32 reg)
> {
> + struct mii_bus *bus = priv->bus;
> u16 r1, r2, page;
> u32 val;
>
> qca8k_split_addr(reg, &r1, &r2, &page);
>
> - mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED);
> + mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
>
> val = qca8k_set_page(priv->bus, page);
> if (val < 0)
> @@ -160,8 +161,7 @@ qca8k_read(struct qca8k_priv *priv, u32 reg)
> val = qca8k_mii_read32(priv->bus, 0x10 | r2, r1);
>
> exit:
> - mutex_unlock(&priv->bus->mdio_lock);
> -
> + mutex_unlock(&bus->mdio_lock);
> return val;

This change does not have anything to do with the commit message.

> }
>
> @@ -226,8 +226,13 @@ static int
> qca8k_regmap_read(void *ctx, uint32_t reg, uint32_t *val)
> {
> struct qca8k_priv *priv = (struct qca8k_priv *)ctx;
> + int ret;
>
> - *val = qca8k_read(priv, reg);
> + ret = qca8k_read(priv, reg);
> + if (ret < 0)
> + return ret;
> +
> + *val = ret;
>
> return 0;
> }
> @@ -280,15 +285,17 @@ static int
> qca8k_busy_wait(struct qca8k_priv *priv, u32 reg, u32 mask)
> {
> unsigned long timeout;
> + u32 val;
>
> timeout = jiffies + msecs_to_jiffies(20);
>
> /* loop until the busy flag has cleared */
> do {
> - u32 val = qca8k_read(priv, reg);
> - int busy = val & mask;
> + val = qca8k_read(priv, reg);
> + if (val < 0)
> + continue;
>
> - if (!busy)
> + if (!(val & mask))
> break;
> cond_resched();

Maybe there is a patch doing this already, but it would be good to
make use of include/linux/iopoll.h

> qca8k_fdb_next(struct qca8k_priv *priv, struct qca8k_fdb *fdb, int port)
> {
> - int ret;
> + int ret, ret_read;
>
> qca8k_fdb_write(priv, fdb->vid, fdb->port_mask, fdb->mac, fdb->aging);
> ret = qca8k_fdb_access(priv, QCA8K_FDB_NEXT, port);
> - if (ret >= 0)
> - qca8k_fdb_read(priv, fdb);
> + if (ret >= 0) {
> + ret_read = qca8k_fdb_read(priv, fdb);
> + if (ret_read < 0)
> + return ret_read;
> + }
>
> return ret;
> }

This is oddly structured. Why not:

qca8k_fdb_next(struct qca8k_priv *priv, struct qca8k_fdb *fdb, int port)
{
int ret;

qca8k_fdb_write(priv, fdb->vid, fdb->port_mask, fdb->mac, fdb->aging);

ret = qca8k_fdb_access(priv, QCA8K_FDB_NEXT, port);
if (ret < 0)
return ret;

return qca8k_fdb_read(priv, fdb);
}

Andrew