[PATCH v3 4/7] slub: Add comments to endif pre-processor macros

Tobin C. Harding
2019-03-14T05:32:27Z

SLUB allocator makes heavy use of ifdef/endif pre-processor macros.
The pairing of these statements is at times hard to follow e.g. if the
pair are further than a screen apart or if there are nested pairs. We
can reduce cognitive load by adding a comment to the endif statement of
form

#ifdef CONFIG_FOO
...
#endif /* CONFIG_FOO */

Add comments to endif pre-processor macros if ifdef/endif pair is not
immediately apparent.

Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
---
mm/slub.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 1b08fbcb7e61..b282e22885cd 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1951,7 +1951,7 @@ static void *get_any_partial(struct kmem_cache *s, gfp_t flags,
}
}
} while (read_mems_allowed_retry(cpuset_mems_cookie));
-#endif
+#endif /* CONFIG_NUMA */
return NULL;
}

@@ -2249,7 +2249,7 @@ static void unfreeze_partials(struct kmem_cache *s,
discard_slab(s, page);
stat(s, FREE_SLAB);
}
-#endif
+#endif /* CONFIG_SLUB_CPU_PARTIAL */
}

/*
@@ -2308,7 +2308,7 @@ static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
local_irq_restore(flags);
}
preempt_enable();
-#endif
+#endif /* CONFIG_SLUB_CPU_PARTIAL */
}

static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
@@ -2813,7 +2813,7 @@ void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
}
EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
#endif
-#endif
+#endif /* CONFIG_NUMA */

/*
* Slow path handling. This may still be called frequently since objects
@@ -3845,7 +3845,7 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node)
return ret;
}
EXPORT_SYMBOL(__kmalloc_node);
-#endif
+#endif /* CONFIG_NUMA */

#ifdef CONFIG_HARDENED_USERCOPY
/*
@@ -4063,7 +4063,7 @@ void __kmemcg_cache_deactivate(struct kmem_cache *s)
*/
slab_deactivate_memcg_cache_rcu_sched(s, kmemcg_cache_deact_after_rcu);
}
-#endif
+#endif /* CONFIG_MEMCG */

static int slab_mem_going_offline_callback(void *arg)
{
@@ -4696,7 +4696,7 @@ static int list_locations(struct kmem_cache *s, char *buf,
len += sprintf(buf, "No data\n");
return len;
}
-#endif
+#endif /* CONFIG_SLUB_DEBUG */

#ifdef SLUB_RESILIENCY_TEST
static void __init resiliency_test(void)
@@ -4756,7 +4756,7 @@ static void __init resiliency_test(void)
#ifdef CONFIG_SYSFS
static void resiliency_test(void) {};
#endif
-#endif
+#endif /* SLUB_RESILIENCY_TEST */

#ifdef CONFIG_SYSFS
enum slab_stat_type {
@@ -5413,7 +5413,7 @@ STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc);
STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free);
STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);
STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);
-#endif
+#endif /* CONFIG_SLUB_STATS */

static struct attribute *slab_attrs[] = {
&slab_size_attr.attr,
@@ -5614,7 +5614,7 @@ static void memcg_propagate_slab_attrs(struct kmem_cache *s)

if (buffer)
free_page((unsigned long)buffer);
-#endif
+#endif /* CONFIG_MEMCG */
}

static void kmem_cache_release(struct kobject *k)
--
2.21.0