linuxkpi: Support non-NULL zero-size pointers
DRM drivers set some pointers to `ZERO_SIZE_PTR` directly (without allocating anything), to treat pointers which were "initialized" (set to `ZERO_SIZE_PTR`) with no memory allocation like really allocated pointers. NULL isn't used because it represents a third state. Reviewed by: emaste, manu Approved by: emaste, manu Differential Revision: https://reviews.freebsd.org/D39055
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@ -90,7 +90,8 @@ struct linux_kmem_cache;
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/* drm-kmod 5.4 compat */
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#define kfree_async(ptr) kfree(ptr);
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#define ZERO_OR_NULL_PTR(x) ((x) == NULL)
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#define ZERO_SIZE_PTR ((void *)16)
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#define ZERO_OR_NULL_PTR(x) ((x) == NULL || (x) == ZERO_SIZE_PTR)
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static inline gfp_t
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linux_check_m_flags(gfp_t flags)
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@ -195,6 +196,9 @@ extern void linux_kfree_async(void *);
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static inline void
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kfree(const void *ptr)
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{
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if (ZERO_OR_NULL_PTR(ptr))
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return;
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if (curthread->td_critnest != 0)
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linux_kfree_async(__DECONST(void *, ptr));
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else
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@ -204,6 +208,9 @@ kfree(const void *ptr)
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static __inline void
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kfree_sensitive(const void *ptr)
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{
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if (ZERO_OR_NULL_PTR(ptr))
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return;
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zfree(__DECONST(void *, ptr), M_KMALLOC);
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}
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