Changeset 649efcd in mainline

Timestamp:

2010-11-05T15:56:29Z (14 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

55bd76c

Parents:

84b7384

Message:

Add support for detecting deadlocks involving fibril rwlocks.

Readers are only tracked when waiting for a rwlock, but it is unfortunatelly not
possible to track their ownership of a rwlock. Because of this, some deadlock
scenarios can go unnoticed by the detection system.

File:

• uspace/lib/c/generic/fibril_synch.c (modified) (6 diffs)

uspace/lib/c/generic/fibril_synch.c

@@ -194 +194 @@
                 f->flags &= ~FIBRIL_WRITER;
                 list_append(&wdata.wu_event.link, &frw->waiters);
+                
+                if (check_for_deadlock(&frw->oi))
+                        print_deadlock(&frw->oi);
+                f->waits_for = &frw->oi;
+                
                 fibril_switch(FIBRIL_TO_MANAGER);
         } else {
@@ -203 +208 @@
 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;
 
@@ -214 +220 @@
                 f->flags |= FIBRIL_WRITER;
                 list_append(&wdata.wu_event.link, &frw->waiters);
+                
+                if (check_for_deadlock(&frw->oi))
+                        print_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);
@@ -234 +246 @@
         assert(!frw->readers && !frw->writers);
         
+        frw->oi.owned_by = NULL;
+        
         while (!list_empty(&frw->waiters)) {
                 link_t *tmp = frw->waiters.next;
@@ -241 +255 @@
                 wdp = list_get_instance(tmp, awaiter_t, wu_event.link);
                 f = (fibril_t *) wdp->fid;
+                
+                f->waits_for = NULL;
                 
                 if (f->flags & FIBRIL_WRITER) {
@@ -250 +266 @@
                         fibril_add_ready(wdp->fid);
                         frw->writers++;
+                        frw->oi.owned_by = f;
                         optimize_execution_power();
                         break;