On Tue, Aug 4, 2015 at 5:55 AM, Dan Carpenter <dan.carpenter@oracle.com> wrote:

On Sat, Aug 01, 2015 at 01:21:09PM +0200, Julia Lawall wrote:
> Currently, is there any documentation about when these functions can be
> used? All I remember seeing is a discussion of what the functions do and
> what functions are available. But nothing about when they should and
> should not be used.
>

The documentation for devm_kmalloc() doesn't list common pitfalls. The
other big one which should be obvious, but happens often is freeing
devm_ memory with kfree().

/**
* devm_kmalloc - Resource-managed kmalloc
* @dev: Device to allocate memory for
* @size: Allocation size
* @gfp: Allocation gfp flags
*
* Managed kmalloc. Memory allocated with this function is
* automatically freed on driver detach. Like all other devres
* resources, guaranteed alignment is unsigned long long.
*
* RETURNS:
* Pointer to allocated memory on success, NULL on failure.
*/

I wonder if it would be possible to note that the current thread is going through probe() or remove() code path in driver core and scream if we encounter devm* call outside of such path. That will give false positives in cases when there is a legitimate mix of automatic and manual resource management (i.e. you rely on automatic cleanup in probe()/remove() but need to free/reallocate object somewhere else), but we can create another call for that.

Thanks.

Dmitry