On Fri, Nov 09, 2018 at 04:42:14PM -0800, Nicolin Chen wrote: > When using DT configurations, the id pointer might turn out to > be NULL. Then the driver encounters NULL pointer access: > > Unable to handle kernel read from unreadable memory at vaddr 00000018 > [...] > PC is at ina2xx_probe+0x114/0x200 > LR is at ina2xx_probe+0x10c/0x200 > [...] > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > > The reason is that i2c core returns the id pointer by matching > id_table with client->name, while the client->name is actually > using the name from the first string in the DT compatible list, > not the best one. So i2c core would fail to match the id_table > if the best matched compatible string isn't the first one, and > then would return a NULL id pointer. > > This probably should be fixed in i2c core. But it doesn't hurt > to make the driver robust. So this patch fixes it by using the > "chip" that's added to unify both DT and non-DT configurations. > > Additionally, since id pointer could be null, so as id->name: > ina2xx 10-0047: power monitor (null) (Rshunt = 1000 uOhm) > ina2xx 10-0048: power monitor (null) (Rshunt = 10000 uOhm) > > So this patch also fixes NULL name pointer, using client->name > to play safe and to align with hwmon->name. > > Fixes: bd0ddd4d0883 ("hwmon: (ina2xx) Add OF device ID table") > Signed-off-by: Nicolin Chen <nicoleotsuka@xxxxxxxxx> Applied. Thanks, Guenter > --- > drivers/hwmon/ina2xx.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c > index 71d3445ba869..c2252cf452f5 100644 > --- a/drivers/hwmon/ina2xx.c > +++ b/drivers/hwmon/ina2xx.c > @@ -491,7 +491,7 @@ static int ina2xx_probe(struct i2c_client *client, > } > > data->groups[group++] = &ina2xx_group; > - if (id->driver_data == ina226) > + if (chip == ina226) > data->groups[group++] = &ina226_group; > > hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, > @@ -500,7 +500,7 @@ static int ina2xx_probe(struct i2c_client *client, > return PTR_ERR(hwmon_dev); > > dev_info(dev, "power monitor %s (Rshunt = %li uOhm)\n", > - id->name, data->rshunt); > + client->name, data->rshunt); > > return 0; > } > -- > 2.17.1 >