Changeset fbcdeb8 in mainline for uspace/lib/fb/screenbuffer.c

Timestamp:

2011-12-19T17:30:39Z (13 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/lib/fb/screenbuffer.c (modified) (1 diff)

uspace/lib/fb/screenbuffer.c

@@ -79 +79 @@
         
         if ((flags & SCREENBUFFER_FLAG_SHARED) == SCREENBUFFER_FLAG_SHARED) {
-                scrbuf = (screenbuffer_t *) as_get_mappable_page(size);
-                
-                if (as_area_create((void *) scrbuf, size, AS_AREA_READ |
-                    AS_AREA_WRITE | AS_AREA_CACHEABLE) != (void *) scrbuf)
+                scrbuf = (screenbuffer_t *) as_area_create((void *) -1, size,
+                    AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE);
+                if (scrbuf == (void *) -1)
                         return NULL;
         } else {