[PATCH v2] PM / devfreq: Fix kernel oops on governor module load

[Ezequiel Garcia <ezequiel@collabora.com>]

A bit unexpectedly (but still documented), request_module may
return a positive value, in case of a modprobe error.
This is currently causing issues in the devfreq framework.

When a request_module exits with a positive value, we currently
return that via ERR_PTR. However, because the value is positive,
it's not a ERR_VALUE proper, and is therefore treated as a
valid struct devfreq_governor pointer, leading to a kernel oops.

Fix this by returning -EINVAL if request_module returns a positive
value.

Fixes: b53b0128052ff ("PM / devfreq: Fix static checker warning in try_then_request_governor")
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
---
Changes from v1:
* Rework the fix as suggested by Enric and Chanwoo,
  handling the return vaue.
---
 drivers/devfreq/devfreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 6b6991f0e873..258f70c1e48f 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -257,7 +257,7 @@ static struct devfreq_governor *try_then_request_governor(const char *name)
 		/* Restore previous state before return */
 		mutex_lock(&devfreq_list_lock);
 		if (err)
-			return ERR_PTR(err);
+			return (err < 0) ? ERR_PTR(err) : ERR_PTR(-EINVAL);
 
 		governor = find_devfreq_governor(name);
 	}
-- 
2.20.1