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

[Ansuel Smith]

On Wed, May 05, 2021 at 02:36:15AM +0200, Andrew Lunn wrote:
> 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@xxxxxxxxx>
> > ---
> >  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.
> 
> >  }

Will split in another patch.

> >  
> > @@ -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
> 

Will check if I can find something to replace this.

> >  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);
> }
> 

It's late here and I could be wrong...
Doesn't your suggested code change the original function return value?
In the original function we returned qca8k_fdb_access, isn't wrong to
return qca8k_fdb_read on success? Or the function was wrong from the
start?

> 	Andrew