On Tue, Jun 19, 2018 at 02:44:00PM +0200, Bartosz Golaszewski wrote:

From: Bartosz Golaszewski bgolaszewski@baylibre.com

This patch reverts commit 3243ff2a05ec ("net: ethernet: davinci_emac: Deduplicate bus_find_device() by name matching") and adds a comment which should stop anyone from reintroducing the same "fix" in the future.

We can't use bus_find_device_by_name() here because the device name is not guaranteed to be 'davinci_mdio'. On some systems it can be 'davinci_mdio.0' so we need to use strncmp() against the first part of the string to correctly match it.

Fixes: 3243ff2a05ec ("net: ethernet: davinci_emac: Deduplicate bus_find_device() by name matching") Cc: stable@vger.kernel.org Signed-off-by: Bartosz Golaszewski bgolaszewski@baylibre.com

Acked-by: Lukas Wunner lukas@wunner.de

My apologies Bartosz, it wasn't clear to me that the driver deliberately only matched against the prefix of the name. Sorry for the breakage.

---

drivers/net/ethernet/ti/davinci_emac.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ti/davinci_emac.c b/drivers/net/ethernet/ti/davinci_emac.c index 06d7c9e4dcda..a1a6445b5a7e 100644 --- a/drivers/net/ethernet/ti/davinci_emac.c +++ b/drivers/net/ethernet/ti/davinci_emac.c @@ -1385,6 +1385,11 @@ static int emac_devioctl(struct net_device *ndev, struct ifreq *ifrq, int cmd) return -EOPNOTSUPP; } +static int match_first_device(struct device *dev, void *data) +{

• return !strncmp(dev_name(dev), "davinci_mdio", 12);

+}

/**

• emac_dev_open - EMAC device open
• @ndev: The DaVinci EMAC network adapter

@@ -1484,8 +1489,14 @@ static int emac_dev_open(struct net_device *ndev) /* use the first phy on the bus if pdata did not give us a phy id */ if (!phydev && !priv->phy_id) {

• phy = bus_find_device_by_name(&mdio_bus_type, NULL,
  

• 			      "davinci_mdio");
  

• /* NOTE: we can't use bus_find_device_by_name() here because
  

•  * the device name is not guaranteed to be 'davinci_mdio'. On
  

•  * some systems it can be 'davinci_mdio.0' so we need to use
  

•  * strncmp() against the first part of the string to correctly
  

•  * match it.
  

•  */
  

• phy = bus_find_device(&mdio_bus_type, NULL, NULL,
  

• 		      match_first_device);
  

  if (phy) { priv->phy_id = dev_name(phy); if (!priv->phy_id || !*priv->phy_id)

-- 2.17.1