WebSVN – HelenOS – Diff – /trunk/uspace/rd/rd.c

 /*
  * Copyright (c) 2007 Michal Konopa
  * Copyright (c) 2007 Martin Jelen
  * Copyright (c) 2007 Peter Majer
+ * Copyright (c) 2007 Jakub Jermar
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /** @addtogroup rd
  * @{
  */
 /**
  * @file    rd.c
  * @brief   Initial RAM disk for HelenOS.
  */
 #include <ipc/ipc.h>
 #include <ipc/services.h>
 #include <ipc/ns.h>
 #include <sysinfo.h>
 #include <as.h>
 #include <ddi.h>
 #include <align.h>
 #include <bool.h>
 #include <errno.h>
 #include <async.h>
 #include <align.h>
 #include <async.h>
+#include <futex.h>
 #include "rd.h"
+/** Pointer to the ramdisk's image. */
 static void *rd_addr;
-static void *fs_addr;
+/**
+ * This futex protects the ramdisk's data.
+ * If we were to serve multiple requests (read + write or several writes)
+ * concurrently (i.e. from two or more threads), each read and write needs to be
+ * protected by this futex.
+ */
+atomic_t rd_futex = FUTEX_INITIALIZER;
+/** Handle one connection to ramdisk.
+ *
+ * @param iid       Hash of the request that opened the connection.
+ * @param icall     Call data of the request that opened the connection.
+ */
 static void rd_connection(ipc_callid_t iid, ipc_call_t *icall)
+{
     ipc_callid_t callid;
     ipc_call_t call;
     int retval;
-    ipc_answer_fast(iid, 0, 0, 0);
+    uintptr_t fs_va = NULL;
     ipcarg_t offset;
+    /*
+     * We allocate VA for communication per connection.
+     * This allows us to potentionally have more clients and work
+     * concurrently.
+     */
+    fs_va = as_get_mappable_page(ALIGN_UP(BLOCK_SIZE, PAGE_SIZE));
+    if (!fs_va) {
+        /*
+         * Hang up the phone if we cannot proceed any further.
+         * This is the answer to the call that opened the connection.
+         */
+        ipc_answer_fast(iid, EHANGUP, 0, 0);
+        return;
+    } else {
+        /*
+         * Answer the first IPC_M_CONNECT_ME_TO call.
+         * Return supported block size as ARG1.
+         */
+        ipc_answer_fast(iid, EOK, BLOCK_SIZE, 0);
+    }
+    /*
+     * Now we wait for the client to send us its communication as_area.
+     */
+    callid = async_get_call(&call);
+    if (IPC_GET_METHOD(call) == IPC_M_AS_AREA_SEND) {
+        if (IPC_GET_ARG1(call) >= (ipcarg_t) BLOCK_SIZE) {
+            /*
+             * The client sends an as_area that can absorb the whole
+             * block.
+             */
+            ipc_answer_fast(callid, EOK, (uintptr_t) fs_va, 0);
+        } else {
+            /*
+             * The client offered as_area too small.
+             * Close the connection.
+             */
+            ipc_answer_fast(callid, EHANGUP, 0, 0);
+            return;
+        }
+    } else {
+        /*
+         * The client doesn't speak the same protocol.
+         * At this point we can't handle protocol variations.
+         * Close the connection.
+         */
+        ipc_answer_fast(callid, EHANGUP, 0, 0);
+        return;
+    }
     while (1) {
         callid = async_get_call(&call);
         switch (IPC_GET_METHOD(call)) {
         case IPC_M_PHONE_HUNGUP:
+            /*
+             * The other side has hung up.
+             * Answer the message and exit the pseudo thread.
+             */
-            ipc_answer_fast(callid, 0, 0, 0);
+            ipc_answer_fast(callid, EOK, 0, 0);
             return;
-        case IPC_M_AS_AREA_SEND:
+        case RD_READ_BLOCK:
+            offset = IPC_GET_ARG1(call);
+            futex_down(&rd_futex);
-            ipc_answer_fast(callid, 0, (uintptr_t) fs_addr, 0);
+            memcpy((void *) fs_va, rd_addr + offset, BLOCK_SIZE);
+            futex_up(&rd_futex);
+            retval = EOK;
-            continue;
+            break;
-        case RD_READ_BLOCK:
+        case RD_WRITE_BLOCK:
             offset = IPC_GET_ARG1(call);
+            futex_up(&rd_futex);
-            memcpy((void *) fs_addr, rd_addr + offset, BLOCK_SIZE);
+            memcpy(rd_addr + offset, (void *) fs_va, BLOCK_SIZE);
+            futex_down(&rd_futex);
             retval = EOK;
             break;
         default:
+            /*
+             * The client doesn't speak the same protocol.
+             * Instead of closing the connection, we just ignore
+             * the call. This can be useful if the client uses a
+             * newer version of the protocol.
+             */
             retval = EINVAL;
+            break;
+        }
         ipc_answer_fast(callid, retval, 0, 0);
+    }
+}
+/** Prepare the ramdisk image for operation. */
 static bool rd_init(void)
+{
     int retval, flags;
     size_t rd_size = sysinfo_value("rd.size");
     void *rd_ph_addr = (void *) sysinfo_value("rd.address.physical");
     if (rd_size == 0)
         return false;
     rd_addr = as_get_mappable_page(rd_size);
     flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE;
     retval = physmem_map(rd_ph_addr, rd_addr,
         ALIGN_UP(rd_size, PAGE_SIZE) >> PAGE_WIDTH, flags);
     if (retval < 0)
         return false;
-    size_t fs_size = ALIGN_UP(BLOCK_SIZE * sizeof(char), PAGE_SIZE);
-    fs_addr = as_get_mappable_page(fs_size);
     return true;
+}
 int main(int argc, char **argv)
+{
     if (rd_init()) {
         ipcarg_t phonead;
         async_set_client_connection(rd_connection);
         /* Register service at nameserver */
         if (ipc_connect_to_me(PHONE_NS, SERVICE_RD, 0, &phonead) != 0)
             return -1;
         async_manager();
         /* Never reached */
         return 0;
+    }
     return -1;
+}
 /**
  * @}
  */

Subversion Repositories HelenOS

(root)/trunk/uspace/rd/rd.c – Rev 2471 → 2475