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authorBartosz Golaszewski <bgolaszewski@baylibre.com>2020-08-24 19:38:57 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-09-08 13:32:06 +0200
commitf82485722e5de5ebb08d3a1dd7302203346dbff9 (patch)
tree66114964163c5ce91e43c99e4cbc0f4b6eebfaa0 /drivers/base/devres.c
parent81b142245b6f0249896325c7e8451cb5347d4d31 (diff)
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: Bartosz Golaszewski <bgolaszewski@baylibre.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20200824173859.4910-2-brgl@bgdev.pl Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/base/devres.c')
-rw-r--r--drivers/base/devres.c105
1 files changed, 105 insertions, 0 deletions
diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index ed615d3b9cf1..586e9a75c840 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -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)
@@ -838,6 +846,103 @@ 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.
* @dev: Device to allocate memory for