Changeset fbcdeb8 in mainline for uspace/srv/bd/rd/rd.c

Timestamp:

2011-12-19T17:30:39Z (12 years ago)

Author:

Martin Decky <martin@…>

Branches:

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

Children:

58f6229

Parents:

24cf31f1

Message:

Remove the two-phase way of creating virtual memory areas (first asking for a mappable address and then mapping it) which was prone to race conditions when two or more calls to as_get_mappable_page() and as_area_create() were interleaved. This for example caused the e1k driver to randomly fail.

The memory area related syscalls and IPC calls have all been altered to accept a special value (void *) -1, representing a demand to atomically search for a mappable address space "hole" and map to it.

Individual changes:

• IPC_M_SHARE_OUT: the destination address space area is supplied by the kernel, the callee only specifies the lower bound

(the address is returned to the callee via a pointer in an IPC reply argument)

• IPC_M_SHARE_IN: the destination address space ares is supplied by the kernel, the callee only specifies the lower bound

(the address is returned to the caller as usual via an IPC argument)

• SYS_AS_GET_UNMAPPED_AREA was removed
• dummy implementations of SYS_PHYSMEM_UNMAP and SYS_IOSPACE_DISABLE were added for the sake of symmetry (they do nothing yet)
• SYS_PHYSMEM_MAP and SYS_DMAMEM_MAP were altered to accept (void *) -1 as address space area base and a lower bound
• kernel as_area_create() and as_area_share() were altered to accept (void *) -1 as address space area base and a lower bound
• uspace libraries and programs were altered to reflect the new API

File:

• uspace/srv/bd/rd/rd.c (modified) (2 diffs)

uspace/srv/bd/rd/rd.c

@@ -105 +105 @@
         unsigned int flags;
         if (async_share_out_receive(&callid, &comm_size, &flags)) {
-                fs_va = as_get_mappable_page(comm_size);
-                if (fs_va) {
-                        (void) async_share_out_finalize(callid, fs_va);
-                } else {
+                (void) async_share_out_finalize(callid, &fs_va);
+                if (fs_va == (void *) -1) {
                         async_answer_0(callid, EHANGUP);
                         return;
@@ -224 +222 @@
         
         rd_size = ALIGN_UP(size, block_size);
-        rd_addr = as_get_mappable_page(rd_size);
-        
         unsigned int flags =
             AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE;
-        ret = physmem_map((void *) addr_phys, rd_addr,
-            ALIGN_UP(rd_size, PAGE_SIZE) >> PAGE_WIDTH, flags);
-        if (ret < 0) {
+        
+        ret = physmem_map((void *) addr_phys,
+            ALIGN_UP(rd_size, PAGE_SIZE) >> PAGE_WIDTH, flags, &rd_addr);
+        if (ret != EOK) {
                 printf("%s: Error mapping RAM disk\n", NAME);
                 return false;