Fix SCTP buffer reallocation for fewer reallocations with small fragm…

…ent size
erlang · Sep 19, 2024 · 73e1aa1 · 73e1aa1
1 parent d3cb78e
commit 73e1aa1
Showing 1 changed file with 14 additions and 10 deletions.
diff --git a/erts/emulator/drivers/common/inet_drv.c b/erts/emulator/drivers/common/inet_drv.c
@@ -14646,16 +14646,20 @@ static int packet_inet_input(udp_descriptor* udesc, HANDLE event)
             ErlDrvBinary* tmp;
 	    int bufsz;
             ASSERT(IS_SCTP(desc));
-	    bufsz = desc->bufsz + (udesc->i_ptr - udesc->i_buf->orig_bytes);
-	    if ((tmp = realloc_buffer(udesc->i_buf, bufsz)) == NULL) {
-		release_buffer(udesc->i_buf);
-		udesc->i_buf = NULL;
-		return packet_error(udesc, ENOMEM);
-	    }
-            udesc->i_ptr =
-                tmp->orig_bytes + (udesc->i_ptr - udesc->i_buf->orig_bytes);
-            udesc->i_buf = tmp;
-            udesc->i_bufsz = bufsz;
+            bufsz = udesc->i_ptr - udesc->i_buf->orig_bytes;
+            if (udesc->i_bufsz - bufsz < desc->bufsz) { /* Headroom */
+                bufsz = udesc->i_bufsz + desc->bufsz;
+                if ((tmp = realloc_buffer(udesc->i_buf, bufsz)) == NULL) {
+                    release_buffer(udesc->i_buf);
+                    udesc->i_buf = NULL;
+                    return packet_error(udesc, ENOMEM);
+                }
+                udesc->i_ptr =
+                    tmp->orig_bytes +
+                    (udesc->i_ptr - udesc->i_buf->orig_bytes);
+                udesc->i_buf = tmp;
+                udesc->i_bufsz = bufsz;
+            }
             have_fragment = TRUE;
 	} else
 #endif