[src/pgoyette-compat]: src/sys/kern Use an SLIST-based stack rather than a st...

[pgoyette <pgoyette%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/d310898eced2
branches:  pgoyette-compat
changeset: 830545:d310898eced2
user:      pgoyette <pgoyette%NetBSD.org@localhost>
date:      Fri Mar 30 23:49:42 2018 +0000

description:
Use an SLIST-based stack rather than a statically-allocated array for
recursion control.  This eliminates the MAXDEPTH constraint.

XXX We still have a static limit on MAXMODDEPS

diffstat:

 sys/kern/kern_module.c |  67 +++++++++++++++++++++++++++----------------------
 1 files changed, 37 insertions(+), 30 deletions(-)

diffs (146 lines):

diff -r 841ecde492be -r d310898eced2 sys/kern/kern_module.c
--- a/sys/kern/kern_module.c    Fri Mar 30 11:29:53 2018 +0000
+++ b/sys/kern/kern_module.c    Fri Mar 30 23:49:42 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_module.c,v 1.130.2.4 2018/03/11 11:47:45 pgoyette Exp $   */
+/*     $NetBSD: kern_module.c,v 1.130.2.5 2018/03/30 23:49:42 pgoyette Exp $   */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_module.c,v 1.130.2.4 2018/03/11 11:47:45 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_module.c,v 1.130.2.5 2018/03/30 23:49:42 pgoyette Exp $");
 
 #define _MODULE_INTERNAL
 
@@ -902,13 +902,19 @@
               prop_dictionary_t props, module_t **modp, modclass_t modclass,
               bool autoload)
 {
-#define MODULE_MAX_DEPTH 6
-
+       /* The pending list for this level of recursion */
        TAILQ_HEAD(pending_t, module);
-       static int depth = 0;
-       static struct pending_t *pending_lists[MODULE_MAX_DEPTH];
        struct pending_t *pending;
        struct pending_t new_pending = TAILQ_HEAD_INITIALIZER(new_pending);
+
+       /* The stack of pending lists */
+       static SLIST_HEAD(pend_head, pend_entry) pend_stack =
+               SLIST_HEAD_INITIALIZER(pend_stack);
+       struct pend_entry {
+               SLIST_ENTRY(pend_entry) pe_entry;
+               struct pending_t *pe_pending;
+       } *my_pend_entry;
+
        modinfo_t *mi;
        module_t *mod, *mod2, *prev_active;
        prop_dictionary_t filedict;
@@ -924,27 +930,21 @@
        error = 0;
 
        /*
-        * Avoid recursing too far.
-        */
-       if (++depth > MODULE_MAX_DEPTH) {
-               module_error("recursion too deep for `%s' %d > %d", name,
-                   depth, MODULE_MAX_DEPTH);
-               depth--;
-               return EMLINK;
-       }
-
-       /*
-        * Set up the pending list for this depth.  If this is a
-        * recursive entry, then use same list as for outer call,
-        * else use the locally allocated list.  In either case,
-        * remember which one we're using.
+        * Set up the pending list for this entry.  If this is an
+        * internal entry (for a dependency), then use the same list
+        * as for the outer call;  otherwise, it's an external entry
+        * (possibly recursive, ie a module's xxx_modcmd(init, ...)
+        * routine called us), so use the locally allocated list.  In
+        * either case, add it to our stack.
         */
        if (isdep) {
-               KASSERT(depth > 1);
-               pending = pending_lists[depth - 2];
+               KASSERT(SLIST_FIRST(&pend_stack) != NULL);
+               pending = SLIST_FIRST(&pend_stack)->pe_pending;
        } else
                pending = &new_pending;
-       pending_lists[depth - 1] = pending;
+       my_pend_entry = kmem_zalloc(sizeof(*my_pend_entry), KM_SLEEP);
+       my_pend_entry->pe_pending = pending;
+       SLIST_INSERT_HEAD(&pend_stack, my_pend_entry, pe_entry);
 
        /*
         * Search the list of disabled builtins first.
@@ -961,11 +961,13 @@
                                module_error("use -f to reinstate "
                                    "builtin module `%s'", name);
                        }
-                       depth--;
+                       SLIST_REMOVE_HEAD(&pend_stack, pe_entry);
+                       kmem_free(my_pend_entry, sizeof(*my_pend_entry));
                        return EPERM;
                } else {
+                       SLIST_REMOVE_HEAD(&pend_stack, pe_entry);
+                       kmem_free(my_pend_entry, sizeof(*my_pend_entry));
                        error = module_do_builtin(mod, name, modp, props);
-                       depth--;
                        return error;
                }
        }
@@ -993,14 +995,16 @@
                        }
                        module_print("%s module `%s' already loaded",
                            isdep ? "dependent" : "requested", name);
-                       depth--;
+                       SLIST_REMOVE_HEAD(&pend_stack, pe_entry);
+                       kmem_free(my_pend_entry, sizeof(*my_pend_entry));
                        return EEXIST;
                }
 
                mod = module_newmodule(MODULE_SOURCE_FILESYS);
                if (mod == NULL) {
                        module_error("out of memory for `%s'", name);
-                       depth--;
+                       SLIST_REMOVE_HEAD(&pend_stack, pe_entry);
+                       kmem_free(my_pend_entry, sizeof(*my_pend_entry));
                        return ENOMEM;
                }
 
@@ -1020,7 +1024,8 @@
                                    "error %d", name, error);
 #endif
                        kmem_free(mod, sizeof(*mod));
-                       depth--;
+                       SLIST_REMOVE_HEAD(&pend_stack, pe_entry);
+                       kmem_free(my_pend_entry, sizeof(*my_pend_entry));
                        return error;
                }
                TAILQ_INSERT_TAIL(pending, mod, mod_chain);
@@ -1235,7 +1240,8 @@
                mod->mod_flags |= MODFLG_AUTO_LOADED;
                module_thread_kick();
        }
-       depth--;
+       SLIST_REMOVE_HEAD(&pend_stack, pe_entry);
+       kmem_free(my_pend_entry, sizeof(*my_pend_entry));
        module_print("module `%s' loaded successfully", mi->mi_name);
        return 0;
 
@@ -1250,7 +1256,8 @@
        }
        TAILQ_REMOVE(pending, mod, mod_chain);
        kmem_free(mod, sizeof(*mod));
-       depth--;
+       SLIST_REMOVE_HEAD(&pend_stack, pe_entry);
+       kmem_free(my_pend_entry, sizeof(*my_pend_entry));
        return error;
 }