[PATCH 2/3 gnumach] vm_map_lookup: Add parameter for exiting with map locked

[Damien Zammit]

This adds a parameter called exit_map_locked to vm_map_lookup()
that allows the function to return with the map locked.

This is to prepare for fixing a bug with gsync where the map
is locked twice by mistake.

Co-Authored-By: Sergey Bugaev <bugaevc@gmail.com>
---
 i386/intel/read_fault.c | 4 ++--
 kern/gsync.c            | 2 +-
 vm/vm_fault.c           | 4 ++--
 vm/vm_map.c             | 7 +++++--
 vm/vm_map.h             | 2 +-
 5 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/i386/intel/read_fault.c b/i386/intel/read_fault.c
index 0b79e3d8..356145e1 100644
--- a/i386/intel/read_fault.c
+++ b/i386/intel/read_fault.c
@@ -61,7 +61,7 @@ intel_read_fault(
         *      Find the backing store object and offset into it
         *      to begin search.
         */
-       result = vm_map_lookup(&map, vaddr, VM_PROT_READ, &version,
+       result = vm_map_lookup(&map, vaddr, VM_PROT_READ, FALSE, &version,
                        &object, &offset, &prot, &wired);
        if (result != KERN_SUCCESS)
            return (result);
@@ -133,7 +133,7 @@ intel_read_fault(
            vm_offset_t         retry_offset;
            vm_prot_t           retry_prot;
 
-           result = vm_map_lookup(&map, vaddr, VM_PROT_READ, &version,
+           result = vm_map_lookup(&map, vaddr, VM_PROT_READ, FALSE, &version,
                                &retry_object, &retry_offset, &retry_prot,
                                &wired);
            if (result != KERN_SUCCESS) {
diff --git a/kern/gsync.c b/kern/gsync.c
index e73a6cf0..19190349 100644
--- a/kern/gsync.c
+++ b/kern/gsync.c
@@ -134,7 +134,7 @@ probe_address (vm_map_t map, vm_offset_t addr,
   vm_prot_t rprot;
   boolean_t wired_p;
 
-  if (vm_map_lookup (&map, addr, prot, &ver,
+  if (vm_map_lookup (&map, addr, prot, FALSE, &ver,
       &vap->obj, &vap->off, &rprot, &wired_p) != KERN_SUCCESS)
     return (-1);
   else if ((rprot & prot) != prot)
diff --git a/vm/vm_fault.c b/vm/vm_fault.c
index c6e28004..d99425a3 100644
--- a/vm/vm_fault.c
+++ b/vm/vm_fault.c
@@ -1213,7 +1213,7 @@ kern_return_t vm_fault(
         *      it to begin the search.
         */
 
-       if ((kr = vm_map_lookup(&map, vaddr, fault_type, &version,
+       if ((kr = vm_map_lookup(&map, vaddr, fault_type, FALSE, &version,
                                &object, &offset,
                                &prot, &wired)) != KERN_SUCCESS) {
                goto done;
@@ -1375,7 +1375,7 @@ kern_return_t vm_fault(
                 *      take another fault.
                 */
                kr = vm_map_lookup(&map, vaddr,
-                                  fault_type & ~VM_PROT_WRITE, &version,
+                                  fault_type & ~VM_PROT_WRITE, FALSE, &version,
                                   &retry_object, &retry_offset, &retry_prot,
                                   &wired);
 
diff --git a/vm/vm_map.c b/vm/vm_map.c
index e4672260..090a5c9c 100644
--- a/vm/vm_map.c
+++ b/vm/vm_map.c
@@ -4627,7 +4627,8 @@ vm_map_t vm_map_fork(vm_map_t old_map)
  *     is returned.
  *
  *     The map should not be locked; it will not be
- *     locked on exit.  In order to guarantee the
+ *     locked on exit unless exit_map_locked is set.
+ *     In order to guarantee the
  *     existence of the returned object, it is returned
  *     locked.
  *
@@ -4640,6 +4641,7 @@ kern_return_t vm_map_lookup(
        vm_map_t                *var_map,       /* IN/OUT */
        vm_offset_t             vaddr,
        vm_prot_t               fault_type,
+       boolean_t               exit_map_locked,
 
        vm_map_version_t        *out_version,   /* OUT */
        vm_object_t             *object,        /* OUT */
@@ -4661,7 +4663,8 @@ kern_return_t vm_map_lookup(
 
 #define        RETURN(why) \
                { \
-               vm_map_unlock_read(map); \
+               if (!exit_map_locked) \
+                 vm_map_unlock_read(map); \
                return(why); \
                }
 
diff --git a/vm/vm_map.h b/vm/vm_map.h
index a4949e4e..7e25d9f4 100644
--- a/vm/vm_map.h
+++ b/vm/vm_map.h
@@ -412,7 +412,7 @@ extern kern_return_t        vm_map_inherit(vm_map_t, 
vm_offset_t, vm_offset_t,
                                       vm_inherit_t);
 
 /* Look up an address */
-extern kern_return_t   vm_map_lookup(vm_map_t *, vm_offset_t, vm_prot_t,
+extern kern_return_t   vm_map_lookup(vm_map_t *, vm_offset_t, vm_prot_t, 
boolean_t,
                                      vm_map_version_t *, vm_object_t *,
                                      vm_offset_t *, vm_prot_t *, boolean_t *);
 /* Find a map entry */
-- 
2.43.0