diff mbox series

[v3,1/3] devres: provide devm_krealloc()

Message ID 20200710161516.11625-2-brgl@bgdev.pl (mailing list archive)
State New, archived
Headers show
Series devres: provide and use devm_krealloc() | expand

Commit Message

Bartosz Golaszewski July 10, 2020, 4:15 p.m. UTC 
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(+)

Comments

Andy Shevchenko July 11, 2020, 3:08 p.m. UTC | #1 
On Fri, Jul 10, 2020 at 7:17 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> 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().

...

>    devm_kfree()
>    devm_kmalloc()
>    devm_kmalloc_array()
> +  devm_krealloc()
>    devm_kmemdup()
>    devm_kstrdup()
>    devm_kvasprintf()

Order?

...

> +void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)

Do we really need the 'new_' prefix in the parameter?

> +{
> +       struct devres *old_dr, *new_dr;
> +       struct list_head old_head;
> +       unsigned long flags;
> +       void *ret = NULL;
> +       size_t tot_size;

tot -> total.

> +
> +       if (unlikely(!new_size)) {
> +               devm_kfree(dev, ptr);
> +               return ZERO_SIZE_PTR;
> +       }

I guess here we need a comment of the possibilities below to have
ZERO_SIZE_PTR as input.

> +       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))

Under spin lock? I would rather see spin unlock followed by WARN.

> +               /* 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;
> +}
Bartosz Golaszewski July 12, 2020, 8:19 a.m. UTC | #2 
On Sat, Jul 11, 2020 at 5:08 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Fri, Jul 10, 2020 at 7:17 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> >
> > 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().
>
> ...
>
> >    devm_kfree()
> >    devm_kmalloc()
> >    devm_kmalloc_array()
> > +  devm_krealloc()
> >    devm_kmemdup()
> >    devm_kstrdup()
> >    devm_kvasprintf()
>
> Order?
>

I didn't notice these were ordered alphabetically, I thought it was by
functionality.

> ...
>
> > +void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
>
> Do we really need the 'new_' prefix in the parameter?
>

Yes, I think this is a good name for a function that's meant to modify
the size of a memory chunk.

> > +{
> > +       struct devres *old_dr, *new_dr;
> > +       struct list_head old_head;
> > +       unsigned long flags;
> > +       void *ret = NULL;
> > +       size_t tot_size;
>
> tot -> total.
>

Meh, ok.

> > +
> > +       if (unlikely(!new_size)) {
> > +               devm_kfree(dev, ptr);
> > +               return ZERO_SIZE_PTR;
> > +       }
>
> I guess here we need a comment of the possibilities below to have
> ZERO_SIZE_PTR as input.
>

Better yet: I'll just add a kernel doc for this function.

> > +       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))
>
> Under spin lock? I would rather see spin unlock followed by WARN.
>

Yeah, can be done.

> > +               /* 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;
> > +}
>
> --
> With Best Regards,
> Andy Shevchenko

Bartosz
diff mbox series

Patch

diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst
index eaaaafc21134..aa08f5162524 100644
--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -353,6 +353,7 @@  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 7322c51e9c0c..f64f40843159 100644
--- a/include/linux/device.h
+++ 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;
 __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,