* [PATCH v2 0/3] Documentation: adopt new coding style of type-aware kmalloc-family
@ 2026-04-21 17:55 Manuel Ebner
2026-04-21 18:01 ` [PATCH v2 1/3] " Manuel Ebner
` (2 more replies)
0 siblings, 3 replies; 10+ messages in thread
From: Manuel Ebner @ 2026-04-21 17:55 UTC (permalink / raw)
To: Jonathan Corbet, Shuah Khan, linux-doc, Kees Cook
Cc: linux-kernel, workflows, linux-sound, rcu, linux-media,
Manuel Ebner
Update the documentation to reflect new type-aware kmalloc-family as
suggested in commit 2932ba8d9c99 ("slab: Introduce kmalloc_obj() and family")
I have also thought about adding a few cases to checkpatch.pl, but this
will take me some time, and i don't know if i can do it.
[v1] -> [v2]:
put RCU/* in a seperate patch [Patch 2/3]
Omit optional argument (GFP_KERNEL) as suggested by https://lwn.net/Articles/1062856/
deprecated.rst: change the argument gfp to optional [Patch 3/3]
Signed-off-by: Manuel Ebner <manuelebner@mailbox.org>
^ permalink raw reply [flat|nested] 10+ messages in thread* [PATCH v2 1/3] Documentation: adopt new coding style of type-aware kmalloc-family 2026-04-21 17:55 [PATCH v2 0/3] Documentation: adopt new coding style of type-aware kmalloc-family Manuel Ebner @ 2026-04-21 18:01 ` Manuel Ebner 2026-04-21 19:24 ` Matthew Wilcox 2026-04-21 18:06 ` [PATCH v2 2/3] Documentation: RCU: " Manuel Ebner 2026-04-21 18:09 ` [PATCH v2 3/3] Documentation: deprecated.rst: kmalloc-family: mark argument as optional Manuel Ebner 2 siblings, 1 reply; 10+ messages in thread From: Manuel Ebner @ 2026-04-21 18:01 UTC (permalink / raw) To: Jonathan Corbet, Shuah Khan, linux-doc Cc: Kees Cook, linux-kernel, workflows, linux-sound, linux-media, Manuel Ebner 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 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v2 1/3] Documentation: adopt new coding style of type-aware kmalloc-family 2026-04-21 18:01 ` [PATCH v2 1/3] " Manuel Ebner @ 2026-04-21 19:24 ` Matthew Wilcox 2026-04-21 19:50 ` Manuel Ebner 0 siblings, 1 reply; 10+ messages in thread From: Matthew Wilcox @ 2026-04-21 19:24 UTC (permalink / raw) To: Manuel Ebner Cc: Jonathan Corbet, Shuah Khan, linux-doc, Kees Cook, linux-kernel, workflows, linux-sound, linux-media On Tue, Apr 21, 2026 at 08:01:58PM +0200, Manuel Ebner wrote: > +++ 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. This seems to have been done without any thought. kmalloc_array() still exists and has over 500 callers. It should not be de-documented. > @@ -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(). Think about why this is wrong too. And you should have cc'd linux-mm on this. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2 1/3] Documentation: adopt new coding style of type-aware kmalloc-family 2026-04-21 19:24 ` Matthew Wilcox @ 2026-04-21 19:50 ` Manuel Ebner 0 siblings, 0 replies; 10+ messages in thread From: Manuel Ebner @ 2026-04-21 19:50 UTC (permalink / raw) To: Matthew Wilcox Cc: Jonathan Corbet, Shuah Khan, linux-doc, Kees Cook, linux-kernel, workflows, linux-sound, linux-media, linux-mm On Tue, 2026-04-21 at 20:24 +0100, Matthew Wilcox wrote: > On Tue, Apr 21, 2026 at 08:01:58PM +0200, Manuel Ebner wrote: > > +++ 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. > > This seems to have been done without any thought. kmalloc_array() still > exists and has over 500 callers. It should not be de-documented. you are right > > @@ -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(). > > Think about why this is wrong too. i see now. > And you should have cc'd linux-mm on this. will add in [v3] thanks, manuel ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v2 2/3] Documentation: RCU: adopt new coding style of type-aware kmalloc-family 2026-04-21 17:55 [PATCH v2 0/3] Documentation: adopt new coding style of type-aware kmalloc-family Manuel Ebner 2026-04-21 18:01 ` [PATCH v2 1/3] " Manuel Ebner @ 2026-04-21 18:06 ` Manuel Ebner 2026-04-21 18:41 ` Paul E. McKenney 2026-04-21 18:09 ` [PATCH v2 3/3] Documentation: deprecated.rst: kmalloc-family: mark argument as optional Manuel Ebner 2 siblings, 1 reply; 10+ messages in thread From: Manuel Ebner @ 2026-04-21 18:06 UTC (permalink / raw) To: Jonathan Corbet, Shuah Khan, linux-doc, rcu; +Cc: Kees Cook, Manuel Ebner Update Documentation/RCU/* 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); Signed-off-by: Manuel Ebner <manuelebner@mailbox.org> --- Documentation/RCU/Design/Requirements/Requirements.rst | 6 +++--- Documentation/RCU/listRCU.rst | 2 +- Documentation/RCU/whatisRCU.rst | 4 ++-- 3 files changed, 6 insertions(+), 6 deletions(-) diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst index b5cdbba3ec2e..faca5a9c8c12 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -206,7 +206,7 @@ non-\ ``NULL``, locklessly accessing the ``->a`` and ``->b`` fields. 1 bool add_gp_buggy(int a, int b) 2 { - 3 p = kmalloc(sizeof(*p), GFP_KERNEL); + 3 p = kmalloc_obj(*p); 4 if (!p) 5 return -ENOMEM; 6 spin_lock(&gp_lock); @@ -228,7 +228,7 @@ their rights to reorder this code as follows: 1 bool add_gp_buggy_optimized(int a, int b) 2 { - 3 p = kmalloc(sizeof(*p), GFP_KERNEL); + 3 p = kmalloc_obj(*p); 4 if (!p) 5 return -ENOMEM; 6 spin_lock(&gp_lock); @@ -264,7 +264,7 @@ shows an example of insertion: 1 bool add_gp(int a, int b) 2 { - 3 p = kmalloc(sizeof(*p), GFP_KERNEL); + 3 p = kmalloc_obj(*p); 4 if (!p) 5 return -ENOMEM; 6 spin_lock(&gp_lock); diff --git a/Documentation/RCU/listRCU.rst b/Documentation/RCU/listRCU.rst index d8bb98623c12..48c7272a4ccc 100644 --- a/Documentation/RCU/listRCU.rst +++ b/Documentation/RCU/listRCU.rst @@ -276,7 +276,7 @@ The RCU version of audit_upd_rule() is as follows:: list_for_each_entry(e, list, list) { if (!audit_compare_rule(rule, &e->rule)) { - ne = kmalloc(sizeof(*entry), GFP_ATOMIC); + ne = kmalloc_obj(*entry, GFP_ATOMIC); if (ne == NULL) return -ENOMEM; audit_copy_rule(&ne->rule, &e->rule); diff --git a/Documentation/RCU/whatisRCU.rst b/Documentation/RCU/whatisRCU.rst index a1582bd653d1..770aab8ea36a 100644 --- a/Documentation/RCU/whatisRCU.rst +++ b/Documentation/RCU/whatisRCU.rst @@ -468,7 +468,7 @@ uses of RCU may be found in listRCU.rst and NMI-RCU.rst. struct foo *new_fp; struct foo *old_fp; - new_fp = kmalloc(sizeof(*new_fp), GFP_KERNEL); + new_fp = kmalloc_obj(*new_fp); spin_lock(&foo_mutex); old_fp = rcu_dereference_protected(gbl_foo, lockdep_is_held(&foo_mutex)); *new_fp = *old_fp; @@ -570,7 +570,7 @@ The foo_update_a() function might then be written as follows:: struct foo *new_fp; struct foo *old_fp; - new_fp = kmalloc(sizeof(*new_fp), GFP_KERNEL); + new_fp = kmalloc_obj(*new_fp); spin_lock(&foo_mutex); old_fp = rcu_dereference_protected(gbl_foo, lockdep_is_held(&foo_mutex)); *new_fp = *old_fp; -- 2.53.0 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v2 2/3] Documentation: RCU: adopt new coding style of type-aware kmalloc-family 2026-04-21 18:06 ` [PATCH v2 2/3] Documentation: RCU: " Manuel Ebner @ 2026-04-21 18:41 ` Paul E. McKenney 0 siblings, 0 replies; 10+ messages in thread From: Paul E. McKenney @ 2026-04-21 18:41 UTC (permalink / raw) To: Manuel Ebner; +Cc: Jonathan Corbet, Shuah Khan, linux-doc, rcu, Kees Cook On Tue, Apr 21, 2026 at 08:06:53PM +0200, Manuel Ebner wrote: > Update Documentation/RCU/* 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); > > Signed-off-by: Manuel Ebner <manuelebner@mailbox.org> Acked-by: Paul E. McKenney <paulmck@kernel.org> > --- > Documentation/RCU/Design/Requirements/Requirements.rst | 6 +++--- > Documentation/RCU/listRCU.rst | 2 +- > Documentation/RCU/whatisRCU.rst | 4 ++-- > 3 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst > index b5cdbba3ec2e..faca5a9c8c12 100644 > --- a/Documentation/RCU/Design/Requirements/Requirements.rst > +++ b/Documentation/RCU/Design/Requirements/Requirements.rst > @@ -206,7 +206,7 @@ non-\ ``NULL``, locklessly accessing the ``->a`` and ``->b`` fields. > > 1 bool add_gp_buggy(int a, int b) > 2 { > - 3 p = kmalloc(sizeof(*p), GFP_KERNEL); > + 3 p = kmalloc_obj(*p); > 4 if (!p) > 5 return -ENOMEM; > 6 spin_lock(&gp_lock); > @@ -228,7 +228,7 @@ their rights to reorder this code as follows: > > 1 bool add_gp_buggy_optimized(int a, int b) > 2 { > - 3 p = kmalloc(sizeof(*p), GFP_KERNEL); > + 3 p = kmalloc_obj(*p); > 4 if (!p) > 5 return -ENOMEM; > 6 spin_lock(&gp_lock); > @@ -264,7 +264,7 @@ shows an example of insertion: > > 1 bool add_gp(int a, int b) > 2 { > - 3 p = kmalloc(sizeof(*p), GFP_KERNEL); > + 3 p = kmalloc_obj(*p); > 4 if (!p) > 5 return -ENOMEM; > 6 spin_lock(&gp_lock); > diff --git a/Documentation/RCU/listRCU.rst b/Documentation/RCU/listRCU.rst > index d8bb98623c12..48c7272a4ccc 100644 > --- a/Documentation/RCU/listRCU.rst > +++ b/Documentation/RCU/listRCU.rst > @@ -276,7 +276,7 @@ The RCU version of audit_upd_rule() is as follows:: > > list_for_each_entry(e, list, list) { > if (!audit_compare_rule(rule, &e->rule)) { > - ne = kmalloc(sizeof(*entry), GFP_ATOMIC); > + ne = kmalloc_obj(*entry, GFP_ATOMIC); > if (ne == NULL) > return -ENOMEM; > audit_copy_rule(&ne->rule, &e->rule); > diff --git a/Documentation/RCU/whatisRCU.rst b/Documentation/RCU/whatisRCU.rst > index a1582bd653d1..770aab8ea36a 100644 > --- a/Documentation/RCU/whatisRCU.rst > +++ b/Documentation/RCU/whatisRCU.rst > @@ -468,7 +468,7 @@ uses of RCU may be found in listRCU.rst and NMI-RCU.rst. > struct foo *new_fp; > struct foo *old_fp; > > - new_fp = kmalloc(sizeof(*new_fp), GFP_KERNEL); > + new_fp = kmalloc_obj(*new_fp); > spin_lock(&foo_mutex); > old_fp = rcu_dereference_protected(gbl_foo, lockdep_is_held(&foo_mutex)); > *new_fp = *old_fp; > @@ -570,7 +570,7 @@ The foo_update_a() function might then be written as follows:: > struct foo *new_fp; > struct foo *old_fp; > > - new_fp = kmalloc(sizeof(*new_fp), GFP_KERNEL); > + new_fp = kmalloc_obj(*new_fp); > spin_lock(&foo_mutex); > old_fp = rcu_dereference_protected(gbl_foo, lockdep_is_held(&foo_mutex)); > *new_fp = *old_fp; > -- > 2.53.0 > > ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v2 3/3] Documentation: deprecated.rst: kmalloc-family: mark argument as optional 2026-04-21 17:55 [PATCH v2 0/3] Documentation: adopt new coding style of type-aware kmalloc-family Manuel Ebner 2026-04-21 18:01 ` [PATCH v2 1/3] " Manuel Ebner 2026-04-21 18:06 ` [PATCH v2 2/3] Documentation: RCU: " Manuel Ebner @ 2026-04-21 18:09 ` Manuel Ebner 2026-04-22 7:14 ` Geert Uytterhoeven 2 siblings, 1 reply; 10+ messages in thread From: Manuel Ebner @ 2026-04-21 18:09 UTC (permalink / raw) To: Jonathan Corbet, Shuah Khan, linux-doc, Kees Cook, linux-kernel Cc: workflows, Manuel Ebner put the optional argument (gfp) in square brackets eg. ptr = kmalloc_obj(*ptr, gfp); -> ptr = kmalloc_obj(*ptr, [gfp]); Signed-off-by: Manuel Ebner <manuelebner@mailbox.org> --- Documentation/process/deprecated.rst | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst index fed56864d036..b431993fd08e 100644 --- a/Documentation/process/deprecated.rst +++ b/Documentation/process/deprecated.rst @@ -392,12 +392,12 @@ allocations. For example, these open coded assignments:: become, respectively:: - ptr = kmalloc_obj(*ptr, gfp); - ptr = kzalloc_obj(*ptr, gfp); - ptr = kmalloc_objs(*ptr, count, gfp); - ptr = kzalloc_objs(*ptr, count, gfp); - ptr = kmalloc_flex(*ptr, flex_member, count, gfp); - __auto_type ptr = kmalloc_obj(struct foo, gfp); + ptr = kmalloc_obj(*ptr, [gfp]); + ptr = kzalloc_obj(*ptr, [gfp]); + ptr = kmalloc_objs(*ptr, count, [gfp]); + ptr = kzalloc_objs(*ptr, count, [gfp]); + ptr = kmalloc_flex(*ptr, flex_member, count, [gfp]); + __auto_type ptr = kmalloc_obj(struct foo, [gfp]); If `ptr->flex_member` is annotated with __counted_by(), the allocation will automatically fail if `count` is larger than the maximum -- 2.53.0 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v2 3/3] Documentation: deprecated.rst: kmalloc-family: mark argument as optional 2026-04-21 18:09 ` [PATCH v2 3/3] Documentation: deprecated.rst: kmalloc-family: mark argument as optional Manuel Ebner @ 2026-04-22 7:14 ` Geert Uytterhoeven 2026-04-22 12:09 ` Manuel Ebner 0 siblings, 1 reply; 10+ messages in thread From: Geert Uytterhoeven @ 2026-04-22 7:14 UTC (permalink / raw) To: Manuel Ebner Cc: Jonathan Corbet, Shuah Khan, linux-doc, Kees Cook, linux-kernel, workflows Hi Manuel, Thanks for your patch! On Tue, 21 Apr 2026 at 20:09, Manuel Ebner <manuelebner@mailbox.org> wrote: > put the optional argument (gfp) in square brackets > > eg. ptr = kmalloc_obj(*ptr, gfp); > -> ptr = kmalloc_obj(*ptr, [gfp]); Shouldn't that be "[, gfp]", e.g. kmalloc_obj(*ptr [, gfp]); everywhere? > Signed-off-by: Manuel Ebner <manuelebner@mailbox.org> Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2 3/3] Documentation: deprecated.rst: kmalloc-family: mark argument as optional 2026-04-22 7:14 ` Geert Uytterhoeven @ 2026-04-22 12:09 ` Manuel Ebner 2026-04-22 12:15 ` Geert Uytterhoeven 0 siblings, 1 reply; 10+ messages in thread From: Manuel Ebner @ 2026-04-22 12:09 UTC (permalink / raw) To: Geert Uytterhoeven Cc: Jonathan Corbet, Shuah Khan, linux-doc, Kees Cook, linux-kernel, workflows On Wed, 2026-04-22 at 09:14 +0200, Geert Uytterhoeven wrote: > Hi Manuel, > > Thanks for your patch! That's good to read. > On Tue, 21 Apr 2026 at 20:09, Manuel Ebner <manuelebner@mailbox.org> wrote: > > put the optional argument (gfp) in square brackets > > > > eg. ptr = kmalloc_obj(*ptr, gfp); > > -> ptr = kmalloc_obj(*ptr, [gfp]); > > Shouldn't that be "[, gfp]", e.g. > > kmalloc_obj(*ptr [, gfp]); I think technically it should be kmalloc_obj(*ptr[, gfp]); but that's difficult to grasp, so i went for my notation. Yours is a good tradeoff. I'll think about it and choose the right one. > > everywhere? > > > Signed-off-by: Manuel Ebner <manuelebner@mailbox.org> > > Gr{oetje,eeting}s, > > Geert ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v2 3/3] Documentation: deprecated.rst: kmalloc-family: mark argument as optional 2026-04-22 12:09 ` Manuel Ebner @ 2026-04-22 12:15 ` Geert Uytterhoeven 0 siblings, 0 replies; 10+ messages in thread From: Geert Uytterhoeven @ 2026-04-22 12:15 UTC (permalink / raw) To: Manuel Ebner Cc: Jonathan Corbet, Shuah Khan, linux-doc, Kees Cook, linux-kernel, workflows Hi Manuel, On Wed, 22 Apr 2026 at 14:10, Manuel Ebner <manuelebner@mailbox.org> wrote: > On Wed, 2026-04-22 at 09:14 +0200, Geert Uytterhoeven wrote: > > On Tue, 21 Apr 2026 at 20:09, Manuel Ebner <manuelebner@mailbox.org> wrote: > > > put the optional argument (gfp) in square brackets > > > > > > eg. ptr = kmalloc_obj(*ptr, gfp); > > > -> ptr = kmalloc_obj(*ptr, [gfp]); > > > > Shouldn't that be "[, gfp]", e.g. > > > > kmalloc_obj(*ptr [, gfp]); > > I think technically it should be > > kmalloc_obj(*ptr[, gfp]); > > but that's difficult to grasp, so i went for my notation. Yours > is a good tradeoff. I'll think about it and choose the right one. A third option is kmalloc_obj(*ptr [, gfp] ); or even: kmalloc_obj(*ptr [ , gfp ] ); Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2026-04-22 12:15 UTC | newest] Thread overview: 10+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2026-04-21 17:55 [PATCH v2 0/3] Documentation: adopt new coding style of type-aware kmalloc-family Manuel Ebner 2026-04-21 18:01 ` [PATCH v2 1/3] " Manuel Ebner 2026-04-21 19:24 ` Matthew Wilcox 2026-04-21 19:50 ` Manuel Ebner 2026-04-21 18:06 ` [PATCH v2 2/3] Documentation: RCU: " Manuel Ebner 2026-04-21 18:41 ` Paul E. McKenney 2026-04-21 18:09 ` [PATCH v2 3/3] Documentation: deprecated.rst: kmalloc-family: mark argument as optional Manuel Ebner 2026-04-22 7:14 ` Geert Uytterhoeven 2026-04-22 12:09 ` Manuel Ebner 2026-04-22 12:15 ` Geert Uytterhoeven
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