Changeset 9413c0d in mainline

Timestamp:

2008-01-06T12:50:51Z (16 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

b3c38750

Parents:

f57f8ea

Message:

Add basic rwlock API for uspace so that VFS can be designed/implemented using
this API. So far, the implementation of this API merely wraps futexes into
rwlocks. Real rwlocks are wanted by ticket #54.

Using the new rwlock API, replace the VFS node content futex with an rwlock.
Lock the contents rwlock as reader on reads and as writer on writes.

Location:

uspace

Files:

• lib/libc/include/rwlock.h (added)
• srv/vfs/vfs.h (modified) (2 diffs)
• srv/vfs/vfs_node.c (modified) (2 diffs)
• srv/vfs/vfs_rdwr.c (modified) (3 diffs)

uspace/srv/vfs/vfs.h

@@ -37 +37 @@
 #include <libadt/list.h>
 #include <atomic.h>
+#include <rwlock.h>
 #include <sys/types.h>
 #include <bool.h>
@@ -136 +137 @@
         link_t nh_link;         /**< Node hash-table link. */
 
-        /** Holding this futex prevents modifications of the node's contents. */
-        atomic_t contents_futex;
+        /** Holding this rwlock prevents modifications of the node's contents. */
+        atomic_t contents_rwlock;
 } vfs_node_t;
 

uspace/srv/vfs/vfs_node.c

@@ -41 +41 @@
 #include <atomic.h>
 #include <futex.h>
+#include <rwlock.h>
 #include <libadt/hash_table.h>
 
@@ -147 +148 @@
                 node->index = triplet->index;
                 link_initialize(&node->nh_link);
-                futex_initialize(&node->contents_futex, 1);
+                rwlock_initialize(&node->contents_rwlock);
                 hash_table_insert(&nodes, key, &node->nh_link);
         } else {

uspace/srv/vfs/vfs_rdwr.c

@@ -40 +40 @@
 #include <async.h>
 #include <errno.h>
-#include <futex.h>
+#include <rwlock.h>
 
 static void vfs_rdwr(ipc_callid_t rid, ipc_call_t *request, bool read)
@@ -86 +86 @@
          * the same time.
          */
-        futex_down(&file->node->contents_futex);
+        if (read)
+                rwlock_reader_lock(&file->node->contents_rwlock);
+        else
+                rwlock_writer_lock(&file->node->contents_rwlock);
 
         int fs_phone = vfs_grab_phone(file->node->fs_handle);   
@@ -118 +121 @@
          * Unlock the VFS node.
          */
-        futex_up(&file->node->contents_futex);
+        if (read)
+                rwlock_reader_unlock(&file->node->contents_rwlock);
+        else
+                rwlock_writer_unlock(&file->node->contents_rwlock);
 
         /*