On Mon, Aug 17, 2020 at 07:05:33PM +0200, Bartosz Golaszewski wrote:

From: Bartosz Golaszewski <redacted>

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



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