git: 208d02fd5d16 - main - linuxkpi: Define `ZERO_OR_NULL_PTR()` in <linux/slab.h>

The branch main has been updated by dumbbell (ports committer):

URL: https://cgit.FreeBSD.org/src/commit/?id=208d02fd5d165389aed0c2b60519cb6b0f5b89f9

commit 208d02fd5d165389aed0c2b60519cb6b0f5b89f9
Author:     Jean-Sébastien Pédron <dumbbell@FreeBSD.org>
AuthorDate: 2022-11-11 20:03:25 +0000
Commit:     Jean-Sébastien Pédron <dumbbell@FreeBSD.org>
CommitDate: 2022-11-11 20:03:25 +0000

    linuxkpi: Define `ZERO_OR_NULL_PTR()` in <linux/slab.h>
    
    On Linux, the `kmalloc()` family of functions returns a special value if
    the size of the allocation is zero. This macro verifies if the pointer
    is NULL (the allocation failed) or the size is 0 (the allocation was not
    performed AFAIU). This special value can be passed to `kfree()`.
    
    On FreeBSD, our `malloc(9)` functions don't return a special value for
    0-size allocations. Therefore we can simply compare the result against
    NULL.
    
    Reviewed by:    manu
    Approved by:    manu
    Differential Revision:  https://reviews.freebsd.org/D37367
---
 sys/compat/linuxkpi/common/include/linux/slab.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sys/compat/linuxkpi/common/include/linux/slab.h b/sys/compat/linuxkpi/common/include/linux/slab.h
index 8f1cb433c36b..915f33acf67e 100644
--- a/sys/compat/linuxkpi/common/include/linux/slab.h
+++ b/sys/compat/linuxkpi/common/include/linux/slab.h
@@ -90,6 +90,8 @@ struct linux_kmem_cache;
 /* drm-kmod 5.4 compat */
 #define kfree_async(ptr)	kfree(ptr);
 
+#define ZERO_OR_NULL_PTR(x)	((x) == NULL)
+
 static inline gfp_t
 linux_check_m_flags(gfp_t flags)
 {