Changeset fbcdeb8 in mainline for uspace/lib/c/generic/async.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/lib/c/generic/async.c (modified) (4 diffs)

uspace/lib/c/generic/async.c

@@ -1998 +1998 @@
  *
  * @param exch  Exchange for sending the message.
- * @param dst   Destination address space area base.
  * @param size  Size of the destination address space area.
  * @param arg   User defined argument.
  * @param flags Storage for the received flags. Can be NULL.
+ * @param dst   Destination address space area base. Cannot be NULL.
  *
  * @return Zero on success or a negative error code from errno.h.
  *
  */
-int async_share_in_start(async_exch_t *exch, void *dst, size_t size,
-    sysarg_t arg, unsigned int *flags)
+int async_share_in_start(async_exch_t *exch, size_t size, sysarg_t arg,
+    unsigned int *flags, void **dst)
 {
         if (exch == NULL)
                 return ENOENT;
         
-        sysarg_t tmp_flags;
-        int res = async_req_3_2(exch, IPC_M_SHARE_IN, (sysarg_t) dst,
-            (sysarg_t) size, arg, NULL, &tmp_flags);
+        sysarg_t _flags = 0;
+        sysarg_t _dst = (sysarg_t) -1;
+        int res = async_req_2_4(exch, IPC_M_SHARE_IN, (sysarg_t) size,
+            arg, NULL, &_flags, NULL, &_dst);
         
         if (flags)
-                *flags = (unsigned int) tmp_flags;
-        
+                *flags = (unsigned int) _flags;
+        
+        *dst = (void *) _dst;
         return res;
 }
@@ -2047 +2049 @@
                 return false;
         
-        *size = (size_t) IPC_GET_ARG2(data);
+        *size = (size_t) IPC_GET_ARG1(data);
         return true;
 }
@@ -2053 +2055 @@
 /** Wrapper for answering the IPC_M_SHARE_IN calls using the async framework.
  *
- * This wrapper only makes it more comfortable to answer IPC_M_DATA_READ
+ * This wrapper only makes it more comfortable to answer IPC_M_SHARE_IN
  * calls so that the user doesn't have to remember the meaning of each IPC
  * argument.
@@ -2131 +2133 @@
  *
  */
-int async_share_out_finalize(ipc_callid_t callid, void *dst)
+int async_share_out_finalize(ipc_callid_t callid, void **dst)
 {
         return ipc_share_out_finalize(callid, dst);