On Wed, Jul 15, 2020 at 11:25:26AM +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().
FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> ---
> .../driver-api/driver-model/devres.rst | 1 +
> drivers/base/devres.c | 68 +++++++++++++++++++
> include/linux/device.h | 2 +
> 3 files changed, 71 insertions(+)
>
> diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst
> index eaaaafc21134f..f318a5c0033c1 100644
> --- a/Documentation/driver-api/driver-model/devres.rst
> +++ b/Documentation/driver-api/driver-model/devres.rst
> @@ -354,6 +354,7 @@ MEM
> devm_kmalloc()
> devm_kmalloc_array()
> devm_kmemdup()
> + devm_krealloc()
> devm_kstrdup()
> devm_kvasprintf()
> devm_kzalloc()
> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> index ed615d3b9cf15..24e27959af270 100644
> --- a/drivers/base/devres.c
> +++ b/drivers/base/devres.c
> @@ -837,6 +837,74 @@ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp)
> }
> EXPORT_SYMBOL_GPL(devm_kmalloc);
>
> +/**
> + * devm_krealloc - Resource-managed krealloc()
> + * @dev: Device to re-allocate memory for
> + * @ptr: Pointer to the memory chunk to re-allocate
> + * @new_size: New allocation size
> + * @gfp: Allocation gfp flags
> + *
> + * Managed krealloc(). Resizes the memory chunk allocated with devm_kmalloc().
> + * Behaves similarly to regular krealloc(): if @ptr is NULL or ZERO_SIZE_PTR,
> + * it's the equivalent of devm_kmalloc(). If new_size is zero, it frees the
> + * previously allocated memory and returns ZERO_SIZE_PTR. This function doesn't
> + * change the order in which the release callback for the re-alloc'ed devres
> + * will be called (except when falling back to devm_kmalloc() or when freeing
> + * resources when new_size is zero). The contents of the memory are preserved
> + * up to the lesser of new and old sizes.
> + */
> +void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
> +{
> + struct devres *old_dr, *new_dr;
> + struct list_head old_head;
> + unsigned long flags;
> + size_t total_size;
> + void *ret = NULL;
> +
> + if (unlikely(!new_size)) {
> + devm_kfree(dev, ptr);
> + return ZERO_SIZE_PTR;
> + }
> +
> + if (unlikely(ZERO_OR_NULL_PTR(ptr)))
> + return devm_kmalloc(dev, new_size, gfp);
> +
> + if (WARN_ON(is_kernel_rodata((unsigned long)ptr)))
> + /*
> + * We cannot reliably realloc a const string returned by
> + * devm_kstrdup_const().
> + */
> + return NULL;
> +
> + if (!check_dr_size(new_size, &total_size))
> + 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);
> + WARN(1, "Memory chunk not managed or managed by a different device.");
> + return NULL;
> + }
> +
> + old_head = old_dr->node.entry;
> +
> + new_dr = krealloc(old_dr, total_size, gfp);
> + if (!new_dr) {
> + spin_unlock_irqrestore(&dev->devres_lock, flags);
> + return NULL;
> + }
> +
> + if (new_dr != old_dr)
> + list_replace(&old_head, &new_dr->node.entry);
> +
> + ret = new_dr->data;
> + spin_unlock_irqrestore(&dev->devres_lock, flags);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(devm_krealloc);
> +
> /**
> * devm_kstrdup - Allocate resource managed space and
> * copy an existing string into that.
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 7322c51e9c0c7..f64f408431593 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -206,6 +206,8 @@ int devres_release_group(struct device *dev, void *id);
>
> /* managed devm_k.alloc/kfree for device drivers */
> void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) __malloc;
> +void *devm_krealloc(struct device *dev, void *ptr, size_t size,
> + gfp_t gfp) __must_check;
> __printf(3, 0) char *devm_kvasprintf(struct device *dev, gfp_t gfp,
> const char *fmt, va_list ap) __malloc;
> __printf(3, 4) char *devm_kasprintf(struct device *dev, gfp_t gfp,
> --
> 2.26.1
>
--
With Best Regards,
Andy Shevchenko
