Re: [PATCH 2/3] thermal: core: Reorder 'thermal_zone_device_register()' error handling code

[Christophe JAILLET]

Le 08/08/2017 à 10:49, Zhang Rui a écrit :
On Sun, 2017-07-16 at 08:59 +0200, Christophe JAILLET wrote:
Reorder code in the error handling path in order to match the way
resources
have been allocated.
With this new order, we can avoid a call to 'device_unregister()' if
'thermal_zone_create_device_groups'()' fails. At this point,
'device_register()' has not been called yet.

Signed-off-by: Christophe JAILLET <christophe.jail...@wanadoo.fr>
---
  drivers/thermal/thermal_core.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/thermal_core.c
b/drivers/thermal/thermal_core.c
index 9743f3e65eb0..c58714800660 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -1232,7 +1232,7 @@ thermal_zone_device_register(const char *type,
int trips, int mask,
        /* Add nodes that are always present via .groups */
        result = thermal_zone_create_device_groups(tz, mask);
        if (result)
-               goto unregister;
+               goto remove_id;

I agree we should release ida and free tz, like you did in this patch.

But the problem is in the code below, where device_register() fails,
we should free the resources allocated in
thermal_zone_create_device_groups() explicitly.

thanks,
rui
Hi,

Thanks for the review.


I will propose a v2 patch serie with some new helper functions:
   void destroy_trip_attrs(struct thermal_zone_device *tz)
   void thermal_zone_destroy_device_groups(struct thermal_zone_device *tz)

'thermal_zone_destroy_device_groups()' will then be called in the error 
handling path of 'thermal_zone_device_register()', when 
'device_register()' fails.


Would you like me to keep the same patch granularity:
   - (new patch in the serie) - Add some new helper functions to free 
resources
   - add kfree(tz) in the actual error handling path    (despite your 
comment on patch 1/3, I still think it is needed in thie error handling 
path)
   - reorder error handling code
   - avoid code duplication

Or the 3 last ones can be merged together under a generic "Fix resources 
release in error paths in thermal_zone_device_register()" ?

CJ

        /* A new thermal zone needs to be updated anyway. */
        atomic_set(&tz->need_update, 1);
@@ -1294,8 +1294,9 @@ thermal_zone_device_register(const char *type,
int trips, int mask,
        return tz;
  
  unregister:
-       ida_simple_remove(&thermal_tz_ida, tz->id);
        device_unregister(&tz->device);
+remove_id:
+       ida_simple_remove(&thermal_tz_ida, tz->id);
        kfree(tz);
        return ERR_PTR(result);
  }