svn commit: r327676 - head/sys/compat/linuxkpi/common/include/linux

[Kristof Provost]

On 7 Jan 2018, at 19:37, Rodney W. Grimes wrote:
>> On 7 Jan 2018, at 19:02, Rodney W. Grimes wrote:
>>>> Author: kp
>>>> Date: Sun Jan  7 13:39:12 2018
>>>> New Revision: 327676
>>>> URL: https://svnweb.freebsd.org/changeset/base/327676
>>>>
>>>> Log:
>>>>   linuxkpi: Implement kcalloc() based on mallocarray()
>>>>
>>>>   This means we now get integer overflow protection, which Linux 
>>>> code
>>>>   might expect as it is also provided by kcalloc() in Linux.
>>>>
>>>> Modified:
>>>>   head/sys/compat/linuxkpi/common/include/linux/slab.h
>>>>
>>>> Modified: head/sys/compat/linuxkpi/common/include/linux/slab.h
>>>> ==============================================================================
>>>> --- head/sys/compat/linuxkpi/common/include/linux/slab.h	Sun Jan  7
>>>> 13:35:15 2018	(r327675)
>>>> +++ head/sys/compat/linuxkpi/common/include/linux/slab.h	Sun Jan  7
>>>> 13:39:12 2018	(r327676)
>>>> @@ -46,7 +46,6 @@ MALLOC_DECLARE(M_KMALLOC);
>>>>  #define	kzalloc(size, flags)		kmalloc(size, (flags) | __GFP_ZERO)
>>>>  #define	kzalloc_node(size, flags, node)	kmalloc(size, (flags) |
>>>> __GFP_ZERO)
>>>>  #define	kfree_const(ptr)		kfree(ptr)
>>>> -#define	kcalloc(n, size, flags)	        kmalloc((n) * (size),
>>>> (flags) | __GFP_ZERO)
>>>
>>> Would not:
>>> #define	kcalloc(n, size, flags)	        mallocarray(mallocarray((n),
>>> (size), M_KMALLOC, linux_check_m_flags((flags | __GFP_ZERO))
>>> work just fine, saving a call and stack use of about framesize + 32
>>> bytes?
>>>
>>>
>> It would also work, but it?d have to be split up into multiple lines
>> then.
>
> But it would retain the direct macro form, your change changes it
> from a #define which is evaluated at pre proc time to a function
> call that is evaluated at compile time.  The resulting code from
> a -O0 well be different because of this.
>
Indeed. It’s not something I’d worry about as anyone who cares about 
it being fast (as opposed to easier to debug for example) would build it 
as -O2/-O3.

>> I thought it?d be more readable as a function.
>
> If that is the only reason I would rather see it retain the
> same form as all the other allocs.
>
How does this look?

	diff --git a/sys/compat/linuxkpi/common/include/linux/slab.h 
b/sys/compat/linuxkpi/common/include/linux/slab.h
	index 1f8ec82db98..5551211c281 100644
	--- a/sys/compat/linuxkpi/common/include/linux/slab.h
	+++ b/sys/compat/linuxkpi/common/include/linux/slab.h
	@@ -46,6 +46,9 @@ MALLOC_DECLARE(M_KMALLOC);
	 #define	kzalloc(size, flags)		kmalloc(size, (flags) | __GFP_ZERO)
	 #define	kzalloc_node(size, flags, node)	kmalloc(size, (flags) | 
__GFP_ZERO)
	 #define	kfree_const(ptr)		kfree(ptr)
	+#define	kcalloc(n, size, flags)		mallocarray((n), (size), \
	+					    M_KMALLOC, \
	+					    linux_check_m_flags((flags | __GFP_ZERO)))
	 #define	vzalloc(size)			__vmalloc(size, GFP_KERNEL | __GFP_NOWARN | 
__GFP_ZERO, 0)
	 #define	vfree(arg)			kfree(arg)
	 #define	kvfree(arg)			kfree(arg)
	@@ -99,13 +102,6 @@ kmalloc(size_t size, gfp_t flags)
	 	return (malloc(size, M_KMALLOC, linux_check_m_flags(flags)));
	 }
	
	-static inline void *
	-kcalloc(size_t n, size_t size, gfp_t flags)
	-{
	-	flags |= __GFP_ZERO;
	-	return (mallocarray(n, size, M_KMALLOC, linux_check_m_flags(flags)));
	-}
	-
	 static inline void *
	 __vmalloc(size_t size, gfp_t flags, int other)
	 {

Regards,
Kristof