Changeset ab9378b4 in mainline for uspace/lib/net/generic/packet_remote.c

Timestamp:

2011-12-16T18:27:50Z (12 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

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

Children:

e1c6dde9

Parents:

0edaf0f6

Message:

Fix serious race in packet_return().

File:

• uspace/lib/net/generic/packet_remote.c (modified) (5 diffs)

uspace/lib/net/generic/packet_remote.c

@@ -38 +38 @@
 #include <async.h>
 #include <errno.h>
+#include <fibril_synch.h>
 #include <ipc/packet.h>
 #include <sys/mman.h>
@@ -46 +47 @@
 #include <net/packet.h>
 #include <net/packet_header.h>
+
+static FIBRIL_MUTEX_INITIALIZE(packet_return_lock);
 
 /** Obtain the packet from the packet server as the shared memory block.
@@ -66 +69 @@
     packet_id_t packet_id, size_t size)
 {
+        /*
+         * Prevent racing for address space with other invocations
+         * of packet_return().
+         *
+         * XXX This of course does not prevent us racing with other
+         * competitors for address space mapping.
+         */
+        fibril_mutex_lock(&packet_return_lock);
         *packet = (packet_t *) as_get_mappable_page(size);
         
@@ -79 +90 @@
         if (rc != EOK) {
                 munmap(*packet, size);
+                fibril_mutex_unlock(&packet_return_lock);
                 return rc;
         }
@@ -85 +97 @@
         if (rc != EOK) {
                 munmap(*packet, size);
+                fibril_mutex_unlock(&packet_return_lock);
                 return rc;
         }
         
+        fibril_mutex_unlock(&packet_return_lock);
         return result;
 }