Changes in uspace/lib/c/generic/fibril_synch.c [9414abc:84b7384] in mainline

File:

• uspace/lib/c/generic/fibril_synch.c (modified) (12 diffs)

uspace/lib/c/generic/fibril_synch.c

@@ -58 +58 @@
 }
 
+static bool check_for_deadlock(fibril_owner_info_t *oi)
+{
+        while (oi && oi->owned_by) {
+                if (oi->owned_by == (fibril_t *) fibril_get_id())
+                        return true;
+                oi = oi->owned_by->waits_for;
+        }
+
+        return false;
+}
+
 static void print_deadlock(fibril_owner_info_t *oi)
 {
@@ -78 +89 @@
                 oi = oi->owned_by->waits_for;
         }
-}
-
-
-static void check_for_deadlock(fibril_owner_info_t *oi)
-{
-        while (oi && oi->owned_by) {
-                if (oi->owned_by == (fibril_t *) fibril_get_id()) {
-                        print_deadlock(oi);
-                        abort();
-                }
-                oi = oi->owned_by->waits_for;
-        }
-}
-
+
+        abort();
+}
 
 void fibril_mutex_initialize(fibril_mutex_t *fm)
@@ -113 +113 @@
                 link_initialize(&wdata.wu_event.link);
                 list_append(&wdata.wu_event.link, &fm->waiters);
-                check_for_deadlock(&fm->oi);
+
+                if (check_for_deadlock(&fm->oi))
+                        print_deadlock(&fm->oi);
                 f->waits_for = &fm->oi;
+
                 fibril_switch(FIBRIL_TO_MANAGER);
         } else {
@@ -180 +183 @@
 void fibril_rwlock_read_lock(fibril_rwlock_t *frw)
 {
-        fibril_t *f = (fibril_t *) fibril_get_id();
-        
         futex_down(&async_futex);
         if (frw->writers) {
+                fibril_t *f = (fibril_t *) fibril_get_id();
                 awaiter_t wdata;
 
@@ -192 +194 @@
                 f->flags &= ~FIBRIL_WRITER;
                 list_append(&wdata.wu_event.link, &frw->waiters);
-                check_for_deadlock(&frw->oi);
-                f->waits_for = &frw->oi;
                 fibril_switch(FIBRIL_TO_MANAGER);
         } else {
-                /* Consider the first reader the owner. */
-                if (frw->readers++ == 0)
-                        frw->oi.owned_by = f;
+                frw->readers++;
                 futex_up(&async_futex);
         }
@@ -205 +203 @@
 void fibril_rwlock_write_lock(fibril_rwlock_t *frw)
 {
-        fibril_t *f = (fibril_t *) fibril_get_id();
-        
         futex_down(&async_futex);
         if (frw->writers || frw->readers) {
+                fibril_t *f = (fibril_t *) fibril_get_id();
                 awaiter_t wdata;
 
@@ -217 +214 @@
                 f->flags |= FIBRIL_WRITER;
                 list_append(&wdata.wu_event.link, &frw->waiters);
-                check_for_deadlock(&frw->oi);
-                f->waits_for = &frw->oi;
                 fibril_switch(FIBRIL_TO_MANAGER);
         } else {
-                frw->oi.owned_by = f;
                 frw->writers++;
                 futex_up(&async_futex);
@@ -232 +226 @@
         assert(frw->readers || (frw->writers == 1));
         if (frw->readers) {
-                if (--frw->readers) {
-                        if (frw->oi.owned_by == (fibril_t *) fibril_get_id()) {
-                                /*
-                                 * If this reader firbril was considered the
-                                 * owner of this rwlock, clear the ownership
-                                 * information even if there are still more
-                                 * readers.
-                                 *
-                                 * This is the limitation of the detection
-                                 * mechanism rooted in the fact that tracking
-                                 * all readers would require dynamically
-                                 * allocated memory for keeping linkage info.
-                                 */
-                                frw->oi.owned_by = NULL;
-                        }
+                if (--frw->readers)
                         goto out;
-                }
         } else {
                 frw->writers--;
@@ -254 +233 @@
         
         assert(!frw->readers && !frw->writers);
-        
-        frw->oi.owned_by = NULL;
         
         while (!list_empty(&frw->waiters)) {
@@ -264 +241 @@
                 wdp = list_get_instance(tmp, awaiter_t, wu_event.link);
                 f = (fibril_t *) wdp->fid;
-                
-                f->waits_for = NULL;
                 
                 if (f->flags & FIBRIL_WRITER) {
@@ -275 +250 @@
                         fibril_add_ready(wdp->fid);
                         frw->writers++;
-                        frw->oi.owned_by = f;
                         optimize_execution_power();
                         break;
@@ -283 +257 @@
                         list_remove(&wdp->wu_event.link);
                         fibril_add_ready(wdp->fid);
-                        if (frw->readers++ == 0) {
-                                /* Consider the first reader the owner. */
-                                frw->oi.owned_by = f;
-                        }
+                        frw->readers++;
                         optimize_execution_power();
                 }