Add independent reader and writer progress checks

[urcu.git] / formal-model / urcu / urcu.spin

diff --git a/formal-model/urcu/urcu.spin b/formal-model/urcu/urcu.spin
index 5ac2f02dd9d80c3abd8d08f2b20136dd9a604635..e9271f82bb58e3acdef1db13aa7226e011d48200 100644 (file)
--- a/formal-model/urcu/urcu.spin
+++ b/formal-model/urcu/urcu.spin
@@ -21,9 +21,9 @@
 /* Promela validation variables. */
 
 #define NR_READERS 1
-#define NR_WRITERS 2
+#define NR_WRITERS 1
 
-#define NR_PROCS 3
+#define NR_PROCS 2
 
 #define get_pid()      (_pid)
 
@@ -144,16 +144,22 @@ inline ooo_mem(i)
 
 inline wait_for_reader(tmp, id, i)
 {
-       tmp = READ_CACHED_VAR(urcu_active_readers_one);
-       ooo_mem(i);
        do
-       :: (tmp & RCU_GP_CTR_NEST_MASK) && ((tmp ^ READ_CACHED_VAR(urcu_gp_ctr))
-                       & RCU_GP_CTR_BIT)
-               ->
-                       ooo_mem(i);
+       :: 1 ->
+               ooo_mem(i);
+               tmp = READ_CACHED_VAR(urcu_active_readers_one);
+               if
+               :: (tmp & RCU_GP_CTR_NEST_MASK)
+                       && ((tmp ^ READ_CACHED_VAR(urcu_gp_ctr))
+                               & RCU_GP_CTR_BIT) ->
+#ifndef GEN_ERROR_WRITER_PROGRESS
+                       smp_mb(i);
+#else
                        skip;
-       :: else ->
+#endif
+               :: else ->
                        break;
+               fi;
        od;
 }
 
@@ -177,33 +183,48 @@ active [NR_READERS] proctype urcu_reader()
 
        assert(get_pid() < NR_PROCS);
 
-       ooo_mem(i);
-       tmp = READ_CACHED_VAR(urcu_active_readers_one);
-       ooo_mem(i);
-       if
-       :: (!(tmp & RCU_GP_CTR_NEST_MASK))
-               ->
-               tmp2 = READ_CACHED_VAR(urcu_gp_ctr);
+end_reader:
+       do
+       :: 1 ->
+               /*
+                * We do not test reader's progress here, because we are mainly
+                * interested in writer's progress. The reader never blocks
+                * anyway. We have to test for reader/writer's progress
+                * separately, otherwise we could think the writer is doing
+                * progress when it's blocked by an always progressing reader.
+                */
+#ifdef READER_PROGRESS
+progress_reader:
+#endif
                ooo_mem(i);
-               WRITE_CACHED_VAR(urcu_active_readers_one, tmp2);
-       :: else ->
-               WRITE_CACHED_VAR(urcu_active_readers_one, tmp + 1);
-       fi;
-       ooo_mem(i);
-       smp_mb(i);
-       read_generation = READ_CACHED_VAR(generation_ptr);
-       ooo_mem(i);
-       data_access = 1;
-       ooo_mem(i);
-       data_access = 0;
-       ooo_mem(i);
-       smp_mb(i);
-       ooo_mem(i);
-       tmp2 = READ_CACHED_VAR(urcu_active_readers_one);
-       ooo_mem(i);
-       WRITE_CACHED_VAR(urcu_active_readers_one, tmp2 - 1);
-       ooo_mem(i);
-       //smp_mc(i);    /* added */
+               tmp = READ_CACHED_VAR(urcu_active_readers_one);
+               ooo_mem(i);
+               if
+               :: (!(tmp & RCU_GP_CTR_NEST_MASK))
+                       ->
+                       tmp2 = READ_CACHED_VAR(urcu_gp_ctr);
+                       ooo_mem(i);
+                       WRITE_CACHED_VAR(urcu_active_readers_one, tmp2);
+               :: else ->
+                       WRITE_CACHED_VAR(urcu_active_readers_one, tmp + 1);
+               fi;
+               ooo_mem(i);
+               smp_mb(i);
+               read_generation = READ_CACHED_VAR(generation_ptr);
+               ooo_mem(i);
+               data_access = 1;
+               ooo_mem(i);
+               data_access = 0;
+               ooo_mem(i);
+               smp_mb(i);
+               ooo_mem(i);
+               tmp2 = READ_CACHED_VAR(urcu_active_readers_one);
+               ooo_mem(i);
+               WRITE_CACHED_VAR(urcu_active_readers_one, tmp2 - 1);
+               ooo_mem(i);
+               //wakeup_all(i);
+               //smp_mc(i);    /* added */
+       od;
 }
 
 
@@ -217,50 +238,70 @@ active [NR_WRITERS] proctype urcu_writer()
 
        assert(get_pid() < NR_PROCS);
 
-       ooo_mem(i);
-       atomic {
-               old_gen = READ_CACHED_VAR(generation_ptr);
-               WRITE_CACHED_VAR(generation_ptr, old_gen + 1);
-       }
-       ooo_mem(i);
-
        do
-       :: 1 ->
+       :: (READ_CACHED_VAR(generation_ptr) < 5) ->
+#ifdef WRITER_PROGRESS
+progress_writer1:
+#endif
+               ooo_mem(i);
                atomic {
-                       if
-                       :: write_lock == 0 ->
-                               write_lock = 1;
-                               break;
-                       :: else ->
-                               skip;
-                       fi;
+                       old_gen = READ_CACHED_VAR(generation_ptr);
+                       WRITE_CACHED_VAR(generation_ptr, old_gen + 1);
                }
+               ooo_mem(i);
+
+               do
+               :: 1 ->
+                       atomic {
+                               if
+                               :: write_lock == 0 ->
+                                       write_lock = 1;
+                                       break;
+                               :: else ->
+                                       skip;
+                               fi;
+                       }
+               od;
+               smp_mb(i);
+               ooo_mem(i);
+               tmp = READ_CACHED_VAR(urcu_gp_ctr);
+               ooo_mem(i);
+               WRITE_CACHED_VAR(urcu_gp_ctr, tmp ^ RCU_GP_CTR_BIT);
+               ooo_mem(i);
+               //smp_mc(i);
+               wait_for_quiescent_state(tmp, i, j);
+               //smp_mc(i);
+       #ifndef SINGLE_FLIP
+               ooo_mem(i);
+               tmp = READ_CACHED_VAR(urcu_gp_ctr);
+               ooo_mem(i);
+               WRITE_CACHED_VAR(urcu_gp_ctr, tmp ^ RCU_GP_CTR_BIT);
+               //smp_mc(i);
+               ooo_mem(i);
+               wait_for_quiescent_state(tmp, i, j);
+       #endif
+               ooo_mem(i);
+               smp_mb(i);
+               ooo_mem(i);
+               write_lock = 0;
+               /* free-up step, e.g., kfree(). */
+               atomic {
+                       last_free_gen = old_gen;
+                       free_done = 1;
+               }
+       :: else -> break;
        od;
-       smp_mb(i);
-       ooo_mem(i);
-       tmp = READ_CACHED_VAR(urcu_gp_ctr);
-       ooo_mem(i);
-       WRITE_CACHED_VAR(urcu_gp_ctr, tmp ^ RCU_GP_CTR_BIT);
-       ooo_mem(i);
-       //smp_mc(i);
-       wait_for_quiescent_state(tmp, i, j);
-       //smp_mc(i);
-#ifndef SINGLE_FLIP
-       ooo_mem(i);
-       tmp = READ_CACHED_VAR(urcu_gp_ctr);
-       ooo_mem(i);
-       WRITE_CACHED_VAR(urcu_gp_ctr, tmp ^ RCU_GP_CTR_BIT);
-       //smp_mc(i);
-       ooo_mem(i);
-       wait_for_quiescent_state(tmp, i, j);
+       /*
+        * Given the reader loops infinitely, let the writer also busy-loop
+        * with progress here so, with weak fairness, we can test the
+        * writer's progress.
+        */
+end_writer:
+       do
+       :: 1 ->
+#ifdef WRITER_PROGRESS
+progress_writer2:
 #endif
-       ooo_mem(i);
-       smp_mb(i);
-       ooo_mem(i);
-       write_lock = 0;
-       /* free-up step, e.g., kfree(). */
-       atomic {
-               last_free_gen = old_gen;
-               free_done = 1;
-       }
+               skip;
+       od;
 }