[LU-16890] allow OBD_FREE() to ignore NULL pointers

Related — Wed, 16 Aug 2023 06:53:23 +0000

The OBD_FREE(ptr) macro will internally (via OBD_FREE_PRE()) assert that ptr != NULL, even though the kernel accepts kfree(NULL) without complaint.

It would make sense to remove the LASSERT(ptr) call from OBD_FREE_PRE() and change the callers to silently accept this case:

#define OBD_FREE(ptr, size)                                                  \
if (likely(ptr)) {                                                           \
        OBD_FREE_PRE(ptr, size, "kfreed");                                   \
        POISON(ptr, 0x5a, size);                                             \
        kfree(ptr);                                                          \
        POISON_PTR(ptr);                                                     \
}

#define OBD_SLAB_FREE(ptr, slab, size)                                       \
if (likely(ptr)) {                                                           \
        OBD_FREE_PRE(ptr, size, "slab-freed");                               \
        POISON(ptr, 0x5a, size);                                             \
        kmem_cache_free(slab, ptr);                                          \
        POISON_PTR(ptr);                                                     \
}

It isn't strictly needed for OBD_FREE_LARGE() since is_vmalloc_addr(ptr) will return false for a NULL pointer and fall back to OBD_FREE().

Whamcloud Community JIRA

[LU-16890] allow OBD_FREE() to ignore NULL pointers