devres: provide and use devm_krealloc()

From: Bartosz Golaszewski <[email protected]>

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 <[email protected]>

---
 .../driver-api/driver-model/devres.rst        |  1 +
 drivers/base/devres.c                         | 67 +++++++++++++++++++
 include/linux/device.h                        |  2 +
 3 files changed, 70 insertions(+)

Documentation/driver-api/driver-model/devres.rst +1 -0

index eaaaafc21134f..f318a5c0033c1 100644
@@ -354,6 +354,7 @@ MEM
   devm_kmalloc()
   devm_kmalloc_array()
   devm_kmemdup()
+  devm_krealloc()
   devm_kstrdup()
   devm_kvasprintf()
   devm_kzalloc()

drivers/base/devres.c +0 -0

index ed615d3b9cf15..1775d35462300 100644
@@ -837,6 +837,73 @@ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp)
 }
 EXPORT_SYMBOL_GPL(devm_kmalloc);
 

). The contents of the memory are preserved up to the
+ * lesser of new and old sizes.
+ */

drivers/base/devres.c +52 -0

+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.

include/linux/device.h +0 -0

index 7322c51e9c0c7..f64f408431593 100644

include/linux/device.h +0 -0

 __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,

Signature · 1 line

2.26.1

Quoted 35 lines · Bartosz Golaszewski

From: Bartosz Golaszewski <[email protected]>

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 <[email protected]>

---
 .../driver-api/driver-model/devres.rst        |  1 +
 drivers/base/devres.c                         | 67 +++++++++++++++++++
 include/linux/device.h                        |  2 +
 3 files changed, 70 insertions(+)

Documentation/driver-api/driver-model/devres.rst +1 -0

index eaaaafc21134f..f318a5c0033c1 100644
@@ -354,6 +354,7 @@ MEM
   devm_kmalloc()
   devm_kmalloc_array()
   devm_kmemdup()
+  devm_krealloc()
   devm_kstrdup()
   devm_kvasprintf()
   devm_kzalloc()

drivers/base/devres.c +0 -0

index ed615d3b9cf15..1775d35462300 100644
@@ -837,6 +837,73 @@ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp)
 }
 EXPORT_SYMBOL_GPL(devm_kmalloc);
 

drivers/base/devres.c void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp) · line 849

Quoted 10 lines

drivers/base/devres.c +10 -0

+/**
+ * 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 returns

'it frees the previously allocated memory and returns'

drivers/base/devres.c void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp)

Quoted 3 lines

drivers/base/devres.c +3 -0

+ * 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'

drivers/base/devres.c int devres_release_group(struct device *dev, void *id); · line 211

Quoted 8 lines

drivers/base/devres.c +3 -0

+++ 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;

Strange indentation, also you can move __must_check to the beginning of the declaration.