The _scoped() version of the fwnode_for_each_available_child_node() follows the approach recently taken for other loops that handle child nodes like for_each_child_of_node_scoped() or device_for_each_child_node_scoped(), which are based on the __free() auto cleanup handler to remove the need for fwnode_handle_put() on early loop exits.
This new variant has been tested with the LTC2992, which currently uses the non-scoped variant. There is one error path that does not decrement the refcount of the child node, which can be fixed by using the new macro. The bug was introduced in a later modification of the loop, which shows how useful an automatic cleanup solution can be in many uses of the non-scoped version.
In order to provide a backportable patch, the conversion in the LTC2992 driver is carried out in two steps: first the missing fwnode_handle_put() is added, and then the code is refactored to adopt the new, safer approach.
@Andy Shevchenko: I kept your Reviewed-by in 3/3, that now also removes the new fwnode_handle_put() and braces added with 1/3.
Signed-off-by: Javier Carrasco javier.carrasco.cruz@gmail.com --- Changes in v2: - Fix the memory leak in a backportable patch and tag it for stable. - Refactor 1/3 with 3/3 as well. - Link to v1: https://lore.kernel.org/r/20240522-fwnode_for_each_available_child_node_scop...
--- Javier Carrasco (3): hwmon: (ltc2992) Fix memory leak in ltc2992_parse_dt() device property: introduce fwnode_for_each_available_child_node_scoped() hwmon: (ltc2992) Use fwnode_for_each_available_child_node_scoped()
drivers/hwmon/ltc2992.c | 11 +++-------- include/linux/property.h | 5 +++++ 2 files changed, 8 insertions(+), 8 deletions(-) --- base-commit: 124cfbcd6d185d4f50be02d5f5afe61578916773 change-id: 20240521-fwnode_for_each_available_child_node_scoped-8f1f09d3a10c
Best regards,
A new error path was added to the fwnode_for_each_available_node() loop in ltc2992_parse_dt(), which leads to an early return that requires a call to fwnode_handle_put() to avoid a memory leak in that case.
Add the missing fwnode_handle_put() in the error path from a zero value shunt resistor.
Cc: stable@vger.kernel.org Fixes: 10b029020487 ("hwmon: (ltc2992) Avoid division by zero") Signed-off-by: Javier Carrasco javier.carrasco.cruz@gmail.com --- drivers/hwmon/ltc2992.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/hwmon/ltc2992.c b/drivers/hwmon/ltc2992.c index 229aed15d5ca..d4a93223cd3b 100644 --- a/drivers/hwmon/ltc2992.c +++ b/drivers/hwmon/ltc2992.c @@ -876,9 +876,11 @@ static int ltc2992_parse_dt(struct ltc2992_state *st)
ret = fwnode_property_read_u32(child, "shunt-resistor-micro-ohms", &val); if (!ret) { - if (!val) + if (!val) { + fwnode_handle_put(child); return dev_err_probe(&st->client->dev, -EINVAL, "shunt resistor value cannot be zero\n"); + } st->r_sense_uohm[addr] = val; } }
On Thu, May 23, 2024 at 05:47:14PM +0200, Javier Carrasco wrote:
A new error path was added to the fwnode_for_each_available_node() loop in ltc2992_parse_dt(), which leads to an early return that requires a call to fwnode_handle_put() to avoid a memory leak in that case.
Add the missing fwnode_handle_put() in the error path from a zero value shunt resistor.
Cc: stable@vger.kernel.org Fixes: 10b029020487 ("hwmon: (ltc2992) Avoid division by zero") Signed-off-by: Javier Carrasco javier.carrasco.cruz@gmail.com
Applied.
Thanks, Guenter
drivers/hwmon/ltc2992.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/hwmon/ltc2992.c b/drivers/hwmon/ltc2992.c index 229aed15d5ca..d4a93223cd3b 100644 --- a/drivers/hwmon/ltc2992.c +++ b/drivers/hwmon/ltc2992.c @@ -876,9 +876,11 @@ static int ltc2992_parse_dt(struct ltc2992_state *st) ret = fwnode_property_read_u32(child, "shunt-resistor-micro-ohms", &val); if (!ret) {
if (!val)
if (!val) {fwnode_handle_put(child); return dev_err_probe(&st->client->dev, -EINVAL, "shunt resistor value cannot be zero\n");} st->r_sense_uohm[addr] = val;
linux-stable-mirror@lists.linaro.org
-
Guenter Roeck -
Javier Carrasco