[PATCH 4/7] calloc: consolidate ENOMEM handling

[Eric Wong <e@80x24.org>]

From: Eric Wong <mwrap-perl@80x24.org>

We can simplify the error paths in calloc and call memset() outside
of the RCU critical section.
---
 mwrap_core.h | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/mwrap_core.h b/mwrap_core.h
index b382018..14e5d79 100644
--- a/mwrap_core.h
+++ b/mwrap_core.h
@@ -662,8 +662,7 @@ void *malloc(size_t size)
 		p = hdr2ptr(h);
 	}
 	update_stats_rcu_unlock(l);
-	if (caa_unlikely(!p)) errno = ENOMEM;
-	return p;
+	if (p) return p;
 enomem:
 	errno = ENOMEM;
 	return 0;
@@ -674,14 +673,10 @@ void *calloc(size_t nmemb, size_t size)
 	size_t asize;
 	size_t generation = 0;
 
-	if (__builtin_mul_overflow(size, nmemb, &size)) {
-		errno = ENOMEM;
-		return 0;
-	}
-	if (__builtin_add_overflow(size, sizeof(struct alloc_hdr), &asize)) {
-		errno = ENOMEM;
-		return 0;
-	}
+	if (__builtin_mul_overflow(size, nmemb, &size))
+		goto enomem;
+	if (__builtin_add_overflow(size, sizeof(struct alloc_hdr), &asize))
+		goto enomem;
 	struct alloc_hdr *h;
 	SRC_LOC_BT(bt);
 	struct src_loc *l = update_stats_rcu_lock(&generation, size, &bt.sl);
@@ -689,11 +684,12 @@ void *calloc(size_t nmemb, size_t size)
 	if (p) {
 		alloc_insert_rcu(l, h, size, h, generation);
 		p = hdr2ptr(h);
-		memset(p, 0, size);
 	}
 	update_stats_rcu_unlock(l);
-	if (caa_unlikely(!p)) errno = ENOMEM;
-	return p;
+	if (p) return memset(p, 0, size);
+enomem:
+	errno = ENOMEM;
+	return 0;
 }
 
 void *realloc(void *ptr, size_t size)