Commit f8248572 authored by Bartosz Golaszewski's avatar Bartosz Golaszewski Committed by Greg Kroah-Hartman
Browse files

devres: provide devm_krealloc() 



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().

Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200824173859.4910-2-brgl@bgdev.pl


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 81b14224

Documentation/driver-api/driver-model/devres.rst

+1 −0
Original line number Diff line number Diff line
@@ -354,6 +354,7 @@ MEM 
  devm_kmalloc()

  devm_kmalloc_array()

  devm_kmemdup()

  devm_krealloc()

  devm_kstrdup()

  devm_kvasprintf()

  devm_kzalloc()

drivers/base/devres.c

+105 −0
Original line number Diff line number Diff line
@@ -126,6 +126,14 @@ static void add_dr(struct device *dev, struct devres_node *node) 
	list_add_tail(&node->entry, &dev->devres_head);

}



static void replace_dr(struct device *dev,

		       struct devres_node *old, struct devres_node *new)

{

	devres_log(dev, old, "REPLACE");

	BUG_ON(!list_empty(&new->entry));

	list_replace(&old->entry, &new->entry);

}



#ifdef CONFIG_DEBUG_DEVRES

void * __devres_alloc_node(dr_release_t release, size_t size, gfp_t gfp, int nid,

		      const char *name)
@@ -837,6 +845,103 @@ 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)

{

	size_t total_new_size, total_old_size;

	struct devres *old_dr, *new_dr;

	unsigned long flags;



	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_new_size))

		return NULL;



	total_old_size = ksize(container_of(ptr, struct devres, data));

	if (total_old_size == 0) {

		WARN(1, "Pointer doesn't point to dynamically allocated memory.");

		return NULL;

	}



	/*

	 * If new size is smaller or equal to the actual number of bytes

	 * allocated previously - just return the same pointer.

	 */

	if (total_new_size <= total_old_size)

		return ptr;



	/*

	 * Otherwise: allocate new, larger chunk. We need to allocate before

	 * taking the lock as most probably the caller uses GFP_KERNEL.

	 */

	new_dr = alloc_dr(devm_kmalloc_release,

			  total_new_size, gfp, dev_to_node(dev));

	if (!new_dr)

		return NULL;



	/*

	 * The spinlock protects the linked list against concurrent

	 * modifications but not the resource itself.

	 */

	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);

		kfree(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);



	/*

	 * We can copy the memory contents after releasing the lock as we're

	 * no longer modyfing the list links.

	 */

	memcpy(new_dr->data, old_dr->data,

	       total_old_size - offsetof(struct devres, data));

	/*

	 * Same for releasing the old devres - it's now been removed from the

	 * list. This is also the reason why we must not use devm_kfree() - the

	 * links are no longer valid.

	 */

	kfree(old_dr);



	return new_dr->data;

}

EXPORT_SYMBOL_GPL(devm_krealloc);



/**

 * devm_kstrdup - Allocate resource managed space and

 *                copy an existing string into that.

include/linux/device.h

+2 −0
Original line number Diff line number Diff line
@@ -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,