Changeset fbcdeb8 in mainline for uspace/lib/net/generic/packet_remote.c

Timestamp:

2011-12-19T17:30:39Z (14 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/net/generic/packet_remote.c (modified) (2 diffs)

uspace/lib/net/generic/packet_remote.c

@@ -66 +66 @@
     packet_id_t packet_id, size_t size)
 {
-        *packet = (packet_t *) as_get_mappable_page(size);
-        
         async_exch_t *exch = async_exchange_begin(sess);
         ipc_call_t answer;
         aid_t message = async_send_1(exch, NET_PACKET_GET, packet_id, &answer);
-        int rc = async_share_in_start_0_0(exch, *packet, size);
+        int rc = async_share_in_start_0_0(exch, size, (void *) packet);
         async_exchange_end(exch);
         
@@ -79 +77 @@
         if (rc != EOK)
                 return rc;
+        
+        if (packet == (void *) -1)
+                return ENOMEM;
         
         rc = pm_add(*packet);