Changes in uspace/lib/c/generic/ipc.c [c170438:d7978525] in mainline

File:

• uspace/lib/c/generic/ipc.c (modified) (17 diffs)

uspace/lib/c/generic/ipc.c

@@ -81 +81 @@
 LIST_INITIALIZE(queued_calls);
 
-static futex_t ipc_futex = FUTEX_INITIALIZER;
+static atomic_t ipc_futex = FUTEX_INITIALIZER;
 
 /** Send asynchronous message via syscall.
@@ -96 +96 @@
 }
 
-/** Prologue for ipc_call_async_*() functions.
+/** Prolog for ipc_call_async_*() functions.
  *
  * @param private  Argument for the answer/error callback.
@@ -122 +122 @@
 }
 
-/** Epilogue for ipc_call_async_*() functions.
+/** Epilog for ipc_call_async_*() functions.
  *
  * @param callid      Value returned by the SYS_IPC_CALL_ASYNC_* syscall.
  * @param phoneid     Phone handle through which the call was made.
  * @param call        Structure returned by ipc_prepare_async().
+ * @param can_preempt If true, the current fibril can be preempted
+ *                    in this call.
+ *
  */
 static inline void ipc_finish_async(ipc_callid_t callid, int phoneid,
-    async_call_t *call)
+    async_call_t *call, bool can_preempt)
 {
         if (!call) {
                 /* Nothing to do regardless if failed or not */
-                futex_unlock(&ipc_futex);
+                futex_up(&ipc_futex);
                 return;
         }
         
         if (callid == (ipc_callid_t) IPC_CALLRET_FATAL) {
-                futex_unlock(&ipc_futex);
+                futex_up(&ipc_futex);
                 
                 /* Call asynchronous handler with error code */
@@ -149 +152 @@
         
         if (callid == (ipc_callid_t) IPC_CALLRET_TEMPORARY) {
-                futex_unlock(&ipc_futex);
+                futex_up(&ipc_futex);
                 
                 call->u.msg.phoneid = phoneid;
@@ -156 +159 @@
                 list_append(&call->list, &queued_calls);
                 
-                call->fid = fibril_get_id();
-                fibril_switch(FIBRIL_TO_MANAGER);
-                /* Async futex unlocked by previous call */
+                if (can_preempt) {
+                        call->fid = fibril_get_id();
+                        fibril_switch(FIBRIL_TO_MANAGER);
+                        /* Async futex unlocked by previous call */
+                } else {
+                        call->fid = 0;
+                        futex_up(&async_futex);
+                }
                 
                 return;
@@ -167 +175 @@
         /* Add call to the list of dispatched calls */
         list_append(&call->list, &dispatched_calls);
-        futex_unlock(&ipc_futex);
+        futex_up(&ipc_futex);
 }
 
@@ -189 +197 @@
  * @param private     Argument to be passed to the answer/error callback.
  * @param callback    Answer or error callback.
+ * @param can_preempt If true, the current fibril will be preempted in
+ *                    case the kernel temporarily refuses to accept more
+ *                    asynchronous calls.
+ *
  */
 void ipc_call_async_fast(int phoneid, sysarg_t imethod, sysarg_t arg1,
     sysarg_t arg2, sysarg_t arg3, sysarg_t arg4, void *private,
-    ipc_async_callback_t callback)
+    ipc_async_callback_t callback, bool can_preempt)
 {
         async_call_t *call = NULL;
@@ -207 +219 @@
          */
         
-        futex_lock(&ipc_futex);
+        futex_down(&ipc_futex);
         ipc_callid_t callid = __SYSCALL6(SYS_IPC_CALL_ASYNC_FAST, phoneid,
             imethod, arg1, arg2, arg3, arg4);
@@ -214 +226 @@
                 if (!call) {
                         call = ipc_prepare_async(private, callback);
-                        if (!call) {
-                                futex_unlock(&ipc_futex);
+                        if (!call)
                                 return;
-                        }
                 }
                 
@@ -234 +244 @@
         }
         
-        ipc_finish_async(callid, phoneid, call);
+        ipc_finish_async(callid, phoneid, call, can_preempt);
 }
 
@@ -254 +264 @@
  * @param private     Argument to be passed to the answer/error callback.
  * @param callback    Answer or error callback.
+ * @param can_preempt If true, the current fibril will be preempted in
+ *                    case the kernel temporarily refuses to accept more
+ *                    asynchronous calls.
+ *
  */
 void ipc_call_async_slow(int phoneid, sysarg_t imethod, sysarg_t arg1,
     sysarg_t arg2, sysarg_t arg3, sysarg_t arg4, sysarg_t arg5, void *private,
-    ipc_async_callback_t callback)
+    ipc_async_callback_t callback, bool can_preempt)
 {
         async_call_t *call = ipc_prepare_async(private, callback);
@@ -275 +289 @@
          */
         
-        futex_lock(&ipc_futex);
+        futex_down(&ipc_futex);
         ipc_callid_t callid =
             ipc_call_async_internal(phoneid, &call->u.msg.data);
         
-        ipc_finish_async(callid, phoneid, call);
+        ipc_finish_async(callid, phoneid, call, can_preempt);
 }
 
@@ -359 +373 @@
                 futex_up(&async_futex);
                 
-                assert(call->fid);
-                fibril_add_ready(call->fid);
+                if (call->fid)
+                        fibril_add_ready(call->fid);
                 
                 if (callid == (ipc_callid_t) IPC_CALLRET_FATAL) {
@@ -370 +384 @@
                         call->u.callid = callid;
                         
-                        futex_lock(&ipc_futex);
+                        futex_down(&ipc_futex);
                         list_append(&call->list, &dispatched_calls);
-                        futex_unlock(&ipc_futex);
+                        futex_up(&ipc_futex);
                 }
                 
@@ -398 +412 @@
         callid &= ~IPC_CALLID_ANSWERED;
         
-        futex_lock(&ipc_futex);
+        futex_down(&ipc_futex);
         
         link_t *item;
@@ -409 +423 @@
                         list_remove(&call->list);
                         
-                        futex_unlock(&ipc_futex);
+                        futex_up(&ipc_futex);
                         
                         if (call->callback)
@@ -420 +434 @@
         }
         
-        futex_unlock(&ipc_futex);
+        futex_up(&ipc_futex);
 }