On Mon, Aug 17, 2020 at 07:05:33PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
>
> Implement the managed variant of krealloc(). This function works with
> all memory allocated by devm_kmalloc() (or devres functions using it
> implicitly like devm_kmemdup(), devm_kstrdup() etc.).
>
> Managed realloc'ed chunks can be manually released with devm_kfree().
Thanks for an update! My comments / questions below.
...
> +static struct devres *to_devres(void *data)
> +{
> + return (struct devres *)((u8 *)data - ALIGN(sizeof(struct devres),
> + ARCH_KMALLOC_MINALIGN));
Do you really need both explicit castings?
> +}
...
> + total_old_size = ksize(to_devres(ptr));
But how you can guarantee this pointer:
- belongs to devres,
- hasn't gone while you run a ksize()?
...
> + new_dr = alloc_dr(devm_kmalloc_release,
> + total_new_size, gfp, dev_to_node(dev));
Can you move some parameters to the previous line?
> + if (!new_dr)
> + return NULL;
...
> + spin_lock_irqsave(&dev->devres_lock, flags);
> +
> + old_dr = find_dr(dev, devm_kmalloc_release, devm_kmalloc_match, ptr);
> + if (!old_dr) {
> + spin_unlock_irqrestore(&dev->devres_lock, flags);
> + devres_free(new_dr);
> + WARN(1, "Memory chunk not managed or managed by a different device.");
> + return NULL;
> + }
> +
> + replace_dr(dev, &old_dr->node, &new_dr->node);
> +
> + spin_unlock_irqrestore(&dev->devres_lock, flags);
> +
> + memcpy(new_dr->data, old_dr->data, devres_data_size(total_old_size));
But new_dr may concurrently gone at this point, no? It means memcpy() should be
under spin lock.
--
With Best Regards,
Andy Shevchenko
