[PATCH v2 1/3] Documentation: adopt new coding style of type-aware kmalloc-family

Manuel Ebner
2026-04-21T18:02:56Z

Update the documentation to reflect new type-aware kmalloc-family as
suggested in commit 2932ba8d9c99 ("slab: Introduce kmalloc_obj() and family")

ptr = kmalloc(sizeof(*ptr), gfp);
-> ptr = kmalloc_obj(*ptr);
ptr = kmalloc(sizeof(struct some_obj_name), gfp);
-> ptr = kmalloc_obj(*ptr);
ptr = kzalloc(sizeof(*ptr), gfp);
-> ptr = kzalloc_obj(*ptr);
ptr = kmalloc_array(count, sizeof(*ptr), gfp);
-> ptr = kmalloc_objs(*ptr, count);
ptr = kcalloc(count, sizeof(*ptr), gfp);
-> ptr = kzalloc_objs(*ptr, count);

Signed-off-by: Manuel Ebner <manuelebner@mailbox.org>
---
Documentation/core-api/kref.rst | 4 ++--
Documentation/core-api/list.rst | 4 ++--
Documentation/core-api/memory-allocation.rst | 4 ++--
Documentation/driver-api/mailbox.rst | 4 ++--
Documentation/driver-api/media/v4l2-fh.rst | 2 +-
Documentation/kernel-hacking/locking.rst | 4 ++--
Documentation/locking/locktypes.rst | 4 ++--
Documentation/process/coding-style.rst | 8 ++++----
.../sound/kernel-api/writing-an-alsa-driver.rst | 12 ++++++------
Documentation/spi/spi-summary.rst | 4 ++--
.../translations/it_IT/kernel-hacking/locking.rst | 4 ++--
.../translations/it_IT/locking/locktypes.rst | 4 ++--
.../translations/it_IT/process/coding-style.rst | 2 +-
.../translations/sp_SP/process/coding-style.rst | 2 +-
Documentation/translations/zh_CN/core-api/kref.rst | 4 ++--
.../translations/zh_CN/process/coding-style.rst | 2 +-
.../zh_CN/video4linux/v4l2-framework.txt | 2 +-
.../translations/zh_TW/process/coding-style.rst | 2 +-
18 files changed, 36 insertions(+), 36 deletions(-)

diff --git a/Documentation/core-api/kref.rst b/Documentation/core-api/kref.rst
index 8db9ff03d952..1c14c036699d 100644
--- a/Documentation/core-api/kref.rst
+++ b/Documentation/core-api/kref.rst
@@ -40,7 +40,7 @@ kref_init as so::

struct my_data *data;

- data = kmalloc(sizeof(*data), GFP_KERNEL);
+ data = kmalloc_obj(*data);
if (!data)
return -ENOMEM;
kref_init(&data->refcount);
@@ -100,7 +100,7 @@ thread to process::
int rv = 0;
struct my_data *data;
struct task_struct *task;
- data = kmalloc(sizeof(*data), GFP_KERNEL);
+ data = kmalloc_obj(*data);
if (!data)
return -ENOMEM;
kref_init(&data->refcount);
diff --git a/Documentation/core-api/list.rst b/Documentation/core-api/list.rst
index 241464ca0549..86cd0a1b77ea 100644
--- a/Documentation/core-api/list.rst
+++ b/Documentation/core-api/list.rst
@@ -112,7 +112,7 @@ list:

/* State 1 */

- grock = kzalloc(sizeof(*grock), GFP_KERNEL);
+ grock = kzalloc_obj(*grock);
if (!grock)
return -ENOMEM;
grock->name = "Grock";
@@ -123,7 +123,7 @@ list:

/* State 2 */

- dimitri = kzalloc(sizeof(*dimitri), GFP_KERNEL);
+ dimitri = kzalloc_obj(*dimitri);
if (!dimitri)
return -ENOMEM;
dimitri->name = "Dimitri";
diff --git a/Documentation/core-api/memory-allocation.rst b/Documentation/core-api/memory-allocation.rst
index 0f19dd524323..8379775f17d3 100644
--- a/Documentation/core-api/memory-allocation.rst
+++ b/Documentation/core-api/memory-allocation.rst
@@ -135,7 +135,7 @@ Selecting memory allocator
The most straightforward way to allocate memory is to use a function
from the kmalloc() family. And, to be on the safe side it's best to use
routines that set memory to zero, like kzalloc(). If you need to
-allocate memory for an array, there are kmalloc_array() and kcalloc()
+allocate memory for an array, there are kmalloc_objs() and kzalloc_objs()
helpers. The helpers struct_size(), array_size() and array3_size() can
be used to safely calculate object sizes without overflowing.

@@ -151,7 +151,7 @@ sizes, the alignment is guaranteed to be at least the largest power-of-two
divisor of the size.

Chunks allocated with kmalloc() can be resized with krealloc(). Similarly
-to kmalloc_array(): a helper for resizing arrays is provided in the form of
+to kmalloc_objs(): a helper for resizing arrays is provided in the form of
krealloc_array().

For large allocations you can use vmalloc() and vzalloc(), or directly
diff --git a/Documentation/driver-api/mailbox.rst b/Documentation/driver-api/mailbox.rst
index 463dd032b96c..4bcd73a99115 100644
--- a/Documentation/driver-api/mailbox.rst
+++ b/Documentation/driver-api/mailbox.rst
@@ -87,8 +87,8 @@ a message and a callback function to the API and return immediately).
struct async_pkt ap;
struct sync_pkt sp;

- dc_sync = kzalloc(sizeof(*dc_sync), GFP_KERNEL);
- dc_async = kzalloc(sizeof(*dc_async), GFP_KERNEL);
+ dc_sync = kzalloc_obj(*dc_sync);
+ dc_async = kzalloc_obj(*dc_async);

/* Populate non-blocking mode client */
dc_async->cl.dev = &pdev->dev;
diff --git a/Documentation/driver-api/media/v4l2-fh.rst b/Documentation/driver-api/media/v4l2-fh.rst
index a934caa483a4..38319130ebf5 100644
--- a/Documentation/driver-api/media/v4l2-fh.rst
+++ b/Documentation/driver-api/media/v4l2-fh.rst
@@ -42,7 +42,7 @@ Example:

...

- my_fh = kzalloc(sizeof(*my_fh), GFP_KERNEL);
+ my_fh = kzalloc_obj(*my_fh);

...

diff --git a/Documentation/kernel-hacking/locking.rst b/Documentation/kernel-hacking/locking.rst
index dff0646a717b..d02e62367c4f 100644
--- a/Documentation/kernel-hacking/locking.rst
+++ b/Documentation/kernel-hacking/locking.rst
@@ -442,7 +442,7 @@ to protect the cache and all the objects within it. Here's the code::
{
struct object *obj;

- if ((obj = kmalloc(sizeof(*obj), GFP_KERNEL)) == NULL)
+ if ((obj = kmalloc_obj(*obj)) == NULL)
return -ENOMEM;

strscpy(obj->name, name, sizeof(obj->name));
@@ -517,7 +517,7 @@ which are taken away, and the ``+`` are lines which are added.
struct object *obj;
+ unsigned long flags;

- if ((obj = kmalloc(sizeof(*obj), GFP_KERNEL)) == NULL)
+ if ((obj = kmalloc_obj(*obj)) == NULL)
return -ENOMEM;
@@ -63,30 +64,33 @@
obj->id = id;
diff --git a/Documentation/locking/locktypes.rst b/Documentation/locking/locktypes.rst
index 37b6a5670c2f..ac1ad722a9e7 100644
--- a/Documentation/locking/locktypes.rst
+++ b/Documentation/locking/locktypes.rst
@@ -498,7 +498,7 @@ allocating memory. Thus, on a non-PREEMPT_RT kernel the following code
works perfectly::

raw_spin_lock(&lock);
- p = kmalloc(sizeof(*p), GFP_ATOMIC);
+ p = kmalloc_obj(*p, GFP_ATOMIC);

But this code fails on PREEMPT_RT kernels because the memory allocator is
fully preemptible and therefore cannot be invoked from truly atomic
@@ -507,7 +507,7 @@ while holding normal non-raw spinlocks because they do not disable
preemption on PREEMPT_RT kernels::

spin_lock(&lock);
- p = kmalloc(sizeof(*p), GFP_ATOMIC);
+ p = kmalloc_obj(*p, GFP_ATOMIC);

bit spinlocks
diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst
index 35b381230f6e..a3bf75dc7c88 100644
--- a/Documentation/process/coding-style.rst
+++ b/Documentation/process/coding-style.rst
@@ -936,7 +936,7 @@ used.
---------------------

The kernel provides the following general purpose memory allocators:
-kmalloc(), kzalloc(), kmalloc_array(), kcalloc(), vmalloc(), and
+kmalloc(), kzalloc(), kmalloc_objs(), kzalloc_objs(), vmalloc(), and
vzalloc(). Please refer to the API documentation for further information
about them. :ref:`Documentation/core-api/memory-allocation.rst
<memory_allocation>`
@@ -945,7 +945,7 @@ The preferred form for passing a size of a struct is the following:

.. code-block:: c

- p = kmalloc(sizeof(*p), ...);
+ p = kmalloc_obj(*p, ...);

The alternative form where struct name is spelled out hurts readability and
introduces an opportunity for a bug when the pointer variable type is changed
@@ -959,13 +959,13 @@ The preferred form for allocating an array is the following:

.. code-block:: c

- p = kmalloc_array(n, sizeof(...), ...);
+ p = kmalloc_objs(*ptr, n, ...);

The preferred form for allocating a zeroed array is the following:

.. code-block:: c

- p = kcalloc(n, sizeof(...), ...);
+ p = kzalloc_objs(*ptr, n, ...);

Both forms check for overflow on the allocation size n * sizeof(...),
and return NULL if that occurred.
diff --git a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
index 895752cbcedd..12433612aa9c 100644
--- a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
+++ b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst
@@ -266,7 +266,7 @@ to details explained in the following section.
....

/* allocate a chip-specific data with zero filled */
- chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+ chip = kzalloc_obj(*chip);
if (chip == NULL)
return -ENOMEM;

@@ -628,7 +628,7 @@ After allocating a card instance via :c:func:`snd_card_new()`
err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
0, &card);
.....
- chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+ chip = kzalloc_obj(*chip);

The chip record should have the field to hold the card pointer at least,

@@ -747,7 +747,7 @@ destructor and PCI entries. Example code is shown first, below::
return -ENXIO;
}

- chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+ chip = kzalloc_obj(*chip);
if (chip == NULL) {
pci_disable_device(pci);
return -ENOMEM;
@@ -1737,7 +1737,7 @@ callback::
{
struct my_pcm_data *data;
....
- data = kmalloc(sizeof(*data), GFP_KERNEL);
+ data = kmalloc_obj(*data);
substream->runtime->private_data = data;
....
}
@@ -3301,7 +3301,7 @@ You can then pass any pointer value to the ``private_data``. If you
assign private data, you should define a destructor, too. The
destructor function is set in the ``private_free`` field::

- struct mydata *p = kmalloc(sizeof(*p), GFP_KERNEL);
+ struct mydata *p = kmalloc_obj(*p);
hw->private_data = p;
hw->private_free = mydata_free;

@@ -3833,7 +3833,7 @@ chip data individually::
err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
0, &card);
....
- chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+ chip = kzalloc_obj(*chip);
....
card->private_data = chip;
....
diff --git a/Documentation/spi/spi-summary.rst b/Documentation/spi/spi-summary.rst
index 6e21e6f86912..7ad6af76c247 100644
--- a/Documentation/spi/spi-summary.rst
+++ b/Documentation/spi/spi-summary.rst
@@ -249,7 +249,7 @@ And SOC-specific utility code might look something like::
{
struct mysoc_spi_data *pdata2;

- pdata2 = kmalloc(sizeof *pdata2, GFP_KERNEL);
+ pdata2 = kmalloc_obj(*pdata2);
*pdata2 = pdata;
...
if (n == 2) {
@@ -373,7 +373,7 @@ a bus (appearing under /sys/class/spi_master).
return -ENODEV;

/* get memory for driver's per-chip state */
- chip = kzalloc(sizeof *chip, GFP_KERNEL);
+ chip = kzalloc(*chip);
if (!chip)
return -ENOMEM;
spi_set_drvdata(spi, chip);
diff --git a/Documentation/translations/it_IT/kernel-hacking/locking.rst b/Documentation/translations/it_IT/kernel-hacking/locking.rst
index 4c21cf60f775..acca89a3743a 100644
--- a/Documentation/translations/it_IT/kernel-hacking/locking.rst
+++ b/Documentation/translations/it_IT/kernel-hacking/locking.rst
@@ -462,7 +462,7 @@ e tutti gli oggetti che contiene. Ecco il codice::
{
struct object *obj;

- if ((obj = kmalloc(sizeof(*obj), GFP_KERNEL)) == NULL)
+ if ((obj = kmalloc_obj(*obj)) == NULL)
return -ENOMEM;

strscpy(obj->name, name, sizeof(obj->name));
@@ -537,7 +537,7 @@ sono quelle rimosse, mentre quelle ``+`` sono quelle aggiunte.
struct object *obj;
+ unsigned long flags;

- if ((obj = kmalloc(sizeof(*obj), GFP_KERNEL)) == NULL)
+ if ((obj = kmalloc_obj(*obj)) == NULL)
return -ENOMEM;
@@ -63,30 +64,33 @@
obj->id = id;
diff --git a/Documentation/translations/it_IT/locking/locktypes.rst b/Documentation/translations/it_IT/locking/locktypes.rst
index 1c7056283b9d..d5fa36aa05cc 100644
--- a/Documentation/translations/it_IT/locking/locktypes.rst
+++ b/Documentation/translations/it_IT/locking/locktypes.rst
@@ -488,7 +488,7 @@ o rwlock_t. Per esempio, la sezione critica non deve fare allocazioni di
memoria. Su un kernel non-PREEMPT_RT il seguente codice funziona perfettamente::

raw_spin_lock(&lock);
- p = kmalloc(sizeof(*p), GFP_ATOMIC);
+ p = kmalloc_obj(*p, GFP_ATOMIC);

Ma lo stesso codice non funziona su un kernel PREEMPT_RT perché l'allocatore di
memoria può essere oggetto di prelazione e quindi non può essere chiamato in un
@@ -497,7 +497,7 @@ trattiene un blocco *non-raw* perché non disabilitano la prelazione sui kernel
PREEMPT_RT::

spin_lock(&lock);
- p = kmalloc(sizeof(*p), GFP_ATOMIC);
+ p = kmalloc_obj(*p, GFP_ATOMIC);

bit spinlocks
diff --git a/Documentation/translations/it_IT/process/coding-style.rst b/Documentation/translations/it_IT/process/coding-style.rst
index c0dc786b8474..2a499412a2e3 100644
--- a/Documentation/translations/it_IT/process/coding-style.rst
+++ b/Documentation/translations/it_IT/process/coding-style.rst
@@ -943,7 +943,7 @@ Il modo preferito per passare la dimensione di una struttura è il seguente:

.. code-block:: c

- p = kmalloc(sizeof(*p), ...);
+ p = kmalloc_obj(*p, ...);

La forma alternativa, dove il nome della struttura viene scritto interamente,
peggiora la leggibilità e introduce possibili bachi quando il tipo di
diff --git a/Documentation/translations/sp_SP/process/coding-style.rst b/Documentation/translations/sp_SP/process/coding-style.rst
index 7d63aa8426e6..44c93d5f6beb 100644
--- a/Documentation/translations/sp_SP/process/coding-style.rst
+++ b/Documentation/translations/sp_SP/process/coding-style.rst
@@ -955,7 +955,7 @@ La forma preferida para pasar el tamaño de una estructura es la siguiente:

.. code-block:: c

- p = kmalloc(sizeof(*p), ...);
+ p = kmalloc_obj(*p, ...);

La forma alternativa donde se deletrea el nombre de la estructura perjudica
la legibilidad, y presenta una oportunidad para un error cuando se cambia
diff --git a/Documentation/translations/zh_CN/core-api/kref.rst b/Documentation/translations/zh_CN/core-api/kref.rst
index b9902af310c5..fcff01e99852 100644
--- a/Documentation/translations/zh_CN/core-api/kref.rst
+++ b/Documentation/translations/zh_CN/core-api/kref.rst
@@ -52,7 +52,7 @@ kref可以出现在数据结构体中的任何地方。

struct my_data *data;

- data = kmalloc(sizeof(*data), GFP_KERNEL);
+ data = kmalloc_obj(*data);
if (!data)
return -ENOMEM;
kref_init(&data->refcount);
@@ -106,7 +106,7 @@ Kref规则
int rv = 0;
struct my_data *data;
struct task_struct *task;
- data = kmalloc(sizeof(*data), GFP_KERNEL);
+ data = kmalloc_obj(*data);
if (!data)
return -ENOMEM;
kref_init(&data->refcount);
diff --git a/Documentation/translations/zh_CN/process/coding-style.rst b/Documentation/translations/zh_CN/process/coding-style.rst
index 5a342a024c01..55d5da974d89 100644
--- a/Documentation/translations/zh_CN/process/coding-style.rst
+++ b/Documentation/translations/zh_CN/process/coding-style.rst
@@ -813,7 +813,7 @@ Documentation/translations/zh_CN/core-api/memory-allocation.rst 。

.. code-block:: c

- p = kmalloc(sizeof(*p), ...);
+ p = kmalloc_obj(*p, ...);

另外一种传递方式中，sizeof 的操作数是结构体的名字，这样会降低可读性，并且可能
会引入 bug。有可能指针变量类型被改变时，而对应的传递给内存分配函数的 sizeof
diff --git a/Documentation/translations/zh_CN/video4linux/v4l2-framework.txt b/Documentation/translations/zh_CN/video4linux/v4l2-framework.txt
index f0be21a60a0f..ba43c5c4797c 100644
--- a/Documentation/translations/zh_CN/video4linux/v4l2-framework.txt
+++ b/Documentation/translations/zh_CN/video4linux/v4l2-framework.txt
@@ -799,7 +799,7 @@ int my_open(struct file *file)

...

- my_fh = kzalloc(sizeof(*my_fh), GFP_KERNEL);
+ my_fh = kzalloc_obj(*my_fh);

...

diff --git a/Documentation/translations/zh_TW/process/coding-style.rst b/Documentation/translations/zh_TW/process/coding-style.rst
index e2ba97b3d8bb..63c78982a1af 100644
--- a/Documentation/translations/zh_TW/process/coding-style.rst
+++ b/Documentation/translations/zh_TW/process/coding-style.rst
@@ -827,7 +827,7 @@ Documentation/translations/zh_CN/core-api/memory-allocation.rst 。

.. code-block:: c

- p = kmalloc(sizeof(*p), ...);
+ p = kmalloc_obj(*p, ...);

另外一種傳遞方式中，sizeof 的操作數是結構體的名字，這樣會降低可讀性，並且可能
會引入 bug。有可能指針變量類型被改變時，而對應的傳遞給內存分配函數的 sizeof
--
2.53.0