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From: Bartosz Golaszewski <brgl@bgdev.pl>
To: Jonathan Corbet <corbet@lwn.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Guenter Roeck <linux@roeck-us.net>,
	Jean Delvare <jdelvare@suse.com>
Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-hwmon@vger.kernel.org,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>
Subject: [PATCH v2 5/6] devres: provide devm_krealloc()
Date: Mon, 29 Jun 2020 08:50:07 +0200
Message-ID: <20200629065008.27620-6-brgl@bgdev.pl> (raw)
In-Reply-To: <20200629065008.27620-1-brgl@bgdev.pl>

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

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>
---
 .../driver-api/driver-model/devres.rst        |  1 +
 drivers/base/devres.c                         | 50 +++++++++++++++++++
 include/linux/device.h                        |  2 +
 3 files changed, 53 insertions(+)

diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst
index e0b58c392e4f..0a2572c3813c 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -352,6 +352,7 @@ MEM
   devm_kfree()
   devm_kmalloc()
   devm_kmalloc_array()
+  devm_krealloc()
   devm_kmemdup()
   devm_kstrdup()
   devm_kvasprintf()
diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index ed615d3b9cf1..4b8870ef6a3f 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -837,6 +837,56 @@ void *devm_kmalloc(struct device *dev, size_t size, gfp_t gfp)
 }
 EXPORT_SYMBOL_GPL(devm_kmalloc);
 
+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;
+	void *ret = NULL;
+	size_t tot_size;
+
+	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, &tot_size))
+		return NULL;
+
+	spin_lock_irqsave(&dev->devres_lock, flags);
+
+	old_dr = find_dr(dev, devm_kmalloc_release, devm_kmalloc_match, ptr);
+	if (WARN_ON(!old_dr))
+		/* Memory chunk not managed or managed by a different device. */
+		goto out;
+
+	old_head = old_dr->node.entry;
+
+	new_dr = krealloc(old_dr, tot_size, gfp);
+	if (!new_dr)
+		goto out;
+
+	if (new_dr != old_dr)
+		list_replace(&old_head, &new_dr->node.entry);
+
+	ret = new_dr->data;
+
+out:
+	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 9cadb647cacc..228063c6392c 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -201,6 +201,8 @@ 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


  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-29  6:50 [PATCH v2 0/6] devres: provide and use devm_krealloc() Bartosz Golaszewski
2020-06-29  6:50 ` [PATCH v2 1/6] devres: remove stray space from devm_kmalloc() definition Bartosz Golaszewski
2020-06-29  6:50 ` [PATCH v2 2/6] devres: move the size check from alloc_dr() into a separate function Bartosz Golaszewski
2020-06-29  6:50 ` [PATCH v2 3/6] device: remove 'extern' attribute from function prototypes in device.h Bartosz Golaszewski
2020-06-29  6:50 ` [PATCH v2 4/6] devres: handle zero size in devm_kmalloc() Bartosz Golaszewski
2020-06-29  6:50 ` Bartosz Golaszewski [this message]
2020-07-02 12:42   ` [PATCH v2 5/6] devres: provide devm_krealloc() Greg Kroah-Hartman
2020-07-02 13:11     ` Bartosz Golaszewski
2020-06-29  6:50 ` [PATCH v2 6/6] hwmon: pmbus: use more devres helpers Bartosz Golaszewski
2020-06-29 16:32   ` Guenter Roeck
2020-07-02 12:44   ` Greg Kroah-Hartman
2020-07-02 13:06     ` Bartosz Golaszewski
2020-07-02 14:29     ` Guenter Roeck
2020-07-02 12:44 ` [PATCH v2 0/6] devres: provide and use devm_krealloc() Greg Kroah-Hartman

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