sfc: Use mutex_lock_interruptible() for ethtool EEPROM access

ethtool must contend with the MTD driver for the SPI bus lock, which
may carry out long operations such as flash erase.  Allow it to be
interrupted while waiting.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/sfc/ethtool.c

@@ -568,10 +568,13 @@ static int efx_ethtool_get_eeprom(struct net_device *net_dev,
 	size_t len;
 	int rc;
 
-	mutex_lock(&efx->spi_lock);
+	rc = mutex_lock_interruptible(&efx->spi_lock);
+	if (rc)
+		return rc;
 	rc = falcon_spi_read(spi, eeprom->offset + EFX_EEPROM_BOOTCONFIG_START,
 			     eeprom->len, &len, buf);
 	mutex_unlock(&efx->spi_lock);
+
 	eeprom->magic = EFX_ETHTOOL_EEPROM_MAGIC;
 	eeprom->len = len;
 	return rc;
@@ -588,10 +591,13 @@ static int efx_ethtool_set_eeprom(struct net_device *net_dev,
 	if (eeprom->magic != EFX_ETHTOOL_EEPROM_MAGIC)
 		return -EINVAL;
 
-	mutex_lock(&efx->spi_lock);
+	rc = mutex_lock_interruptible(&efx->spi_lock);
+	if (rc)
+		return rc;
 	rc = falcon_spi_write(spi, eeprom->offset + EFX_EEPROM_BOOTCONFIG_START,
 			      eeprom->len, &len, buf);
 	mutex_unlock(&efx->spi_lock);
+
 	eeprom->len = len;
 	return rc;
 }