byte val[NR_PROCS];
};
-/* Bitfield has a maximum of 8 procs */
typedef per_proc_bit {
+ bit val[NR_PROCS];
+};
+
+/* Bitfield has a maximum of 8 procs */
+typedef per_proc_bitfield {
byte bitfield;
};
#define DECLARE_CACHED_VAR(type, x) \
type mem_##x; \
per_proc_##type cached_##x; \
- per_proc_bit cache_dirty_##x;
+ per_proc_bitfield cache_dirty_##x;
#define INIT_CACHED_VAR(x, v, j) \
mem_##x = v; \
i++
:: i >= NR_READERS -> break
od;
- CACHE_READ_FROM_MEM(generation_ptr, get_pid());
+ CACHE_READ_FROM_MEM(rcu_ptr, get_pid());
+ i = 0;
+ do
+ :: i < SLAB_SIZE ->
+ CACHE_READ_FROM_MEM(rcu_data[i], get_pid());
+ i++
+ :: i >= SLAB_SIZE -> break
+ od;
}
}
i++
:: i >= NR_READERS -> break
od;
- CACHE_WRITE_TO_MEM(generation_ptr, get_pid());
+ CACHE_WRITE_TO_MEM(rcu_ptr, get_pid());
+ i = 0;
+ do
+ :: i < SLAB_SIZE ->
+ CACHE_WRITE_TO_MEM(rcu_data[i], get_pid());
+ i++
+ :: i >= SLAB_SIZE -> break
+ od;
}
}
{
do
:: (reader_barrier[get_readerid()] == 1) ->
+ /*
+ * We choose to ignore cycles caused by writer busy-looping,
+ * waiting for the reader, sending barrier requests, and the
+ * reader always services them without continuing execution.
+ */
+progress_ignoring_mb1:
smp_mb(i, j);
reader_barrier[get_readerid()] = 0;
:: 1 ->
- /*
- * Busy-looping waiting for other barrier requests are not considered as
- * non-progress.
- */
-#ifdef READER_PROGRESS
-progress_reader2:
-#endif
- skip;
- :: 1 -> break;
+ /*
+ * We choose to ignore writer's non-progress caused by the
+ * reader ignoring the writer's mb() requests.
+ */
+progress_ignoring_mb2:
+ break;
od;
}
-#ifdef WRITER_PROGRESS
#define PROGRESS_LABEL(progressid) progress_writer_progid_##progressid:
-#else
-#define PROGRESS_LABEL(progressid)
-#endif
#define smp_mb_send(i, j, progressid) \
{ \
do \
:: i < NR_READERS -> \
reader_barrier[i] = 1; \
- do \
- :: (reader_barrier[i] == 1) -> \
/* \
* Busy-looping waiting for reader barrier handling is of little\
* interest, given the reader has the ability to totally ignore \
* barrier requests. \
*/ \
+ do \
+ :: (reader_barrier[i] == 1) -> \
PROGRESS_LABEL(progressid) \
skip; \
:: (reader_barrier[i] == 0) -> break; \
#else
-#define smp_mb_send smp_mb
+#define smp_mb_send(i, j, progressid) smp_mb(i, j)
#define smp_mb_reader smp_mb
#define smp_mb_recv(i, j)
#endif
-/* Keep in sync manually with smp_rmb, wmp_wmb, ooo_mem and init() */
+/* Keep in sync manually with smp_rmb, smp_wmb, ooo_mem and init() */
DECLARE_CACHED_VAR(byte, urcu_gp_ctr);
-/* Note ! currently only two readers */
+/* Note ! currently only one reader */
DECLARE_CACHED_VAR(byte, urcu_active_readers[NR_READERS]);
-/* pointer generation */
-DECLARE_CACHED_VAR(byte, generation_ptr);
-
-byte last_free_gen = 0;
-bit free_done = 0;
-byte read_generation[NR_READERS];
-bit data_access[NR_READERS];
+/* RCU data */
+DECLARE_CACHED_VAR(bit, rcu_data[SLAB_SIZE]);
+
+/* RCU pointer */
+#if (SLAB_SIZE == 2)
+DECLARE_CACHED_VAR(bit, rcu_ptr);
+bit ptr_read_first[NR_READERS];
+bit ptr_read_second[NR_READERS];
+#else
+DECLARE_CACHED_VAR(byte, rcu_ptr);
+byte ptr_read_first[NR_READERS];
+byte ptr_read_second[NR_READERS];
+#endif
-bit write_lock = 0;
+bit data_read_first[NR_READERS];
+bit data_read_second[NR_READERS];
bit init_done = 0;
-bit sighand_exec = 0;
-
inline wait_init_done()
{
do
i++
:: i >= NR_READERS -> break
od;
- RANDOM_CACHE_WRITE_TO_MEM(generation_ptr, get_pid());
+ RANDOM_CACHE_WRITE_TO_MEM(rcu_ptr, get_pid());
+ i = 0;
+ do
+ :: i < SLAB_SIZE ->
+ RANDOM_CACHE_WRITE_TO_MEM(rcu_data[i], get_pid());
+ i++
+ :: i >= SLAB_SIZE -> break
+ od;
RANDOM_CACHE_READ_FROM_MEM(urcu_gp_ctr, get_pid());
i = 0;
do
i++
:: i >= NR_READERS -> break
od;
- RANDOM_CACHE_READ_FROM_MEM(generation_ptr, get_pid());
+ RANDOM_CACHE_READ_FROM_MEM(rcu_ptr, get_pid());
+ i = 0;
+ do
+ :: i < SLAB_SIZE ->
+ RANDOM_CACHE_READ_FROM_MEM(rcu_data[i], get_pid());
+ i++
+ :: i >= SLAB_SIZE -> break
+ od;
}
}
skip;
fi;
}
- :: 1 -> skip;
fi;
goto non_atomic3_skip;
READ_PROC_FIRST_MB, /* mb() orders reads */
READ_PROC_READ_GEN) ->
ooo_mem(i);
- read_generation[get_readerid()] =
- READ_CACHED_VAR(generation_ptr);
+ ptr_read_first[get_readerid()] = READ_CACHED_VAR(rcu_ptr);
PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_READ_GEN);
:: CONSUME_TOKENS(proc_urcu_reader,
READ_PROC_FIRST_MB /* mb() orders reads */
| READ_PROC_READ_GEN,
READ_PROC_ACCESS_GEN) ->
- ooo_mem(i);
- goto non_atomic;
-non_atomic_end:
+ /* smp_read_barrier_depends */
+ goto rmb1;
+rmb1_end:
+ data_read_first[get_readerid()] =
+ READ_CACHED_VAR(rcu_data[ptr_read_first[get_readerid()]]);
PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_ACCESS_GEN);
| READ_PROC_THIRD_MB, /* mb() orders reads */
READ_PROC_READ_GEN_UNROLL) ->
ooo_mem(i);
- read_generation[get_readerid()] =
- READ_CACHED_VAR(generation_ptr);
+ ptr_read_second[get_readerid()] = READ_CACHED_VAR(rcu_ptr);
PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_READ_GEN_UNROLL);
:: CONSUME_TOKENS(proc_urcu_reader,
| READ_PROC_SECOND_MB /* mb() orders reads */
| READ_PROC_THIRD_MB, /* mb() orders reads */
READ_PROC_ACCESS_GEN_UNROLL) ->
- ooo_mem(i);
- goto non_atomic2;
-non_atomic2_end:
+ /* smp_read_barrier_depends */
+ goto rmb2;
+rmb2_end:
+ data_read_second[get_readerid()] =
+ READ_CACHED_VAR(rcu_data[ptr_read_second[get_readerid()]]);
PRODUCE_TOKENS(proc_urcu_reader, READ_PROC_ACCESS_GEN_UNROLL);
:: CONSUME_TOKENS(proc_urcu_reader,
* to spill its execution on other loop's execution.
*/
goto end;
-non_atomic:
- data_access[get_readerid()] = 1;
- data_access[get_readerid()] = 0;
- goto non_atomic_end;
-non_atomic2:
- data_access[get_readerid()] = 1;
- data_access[get_readerid()] = 0;
- goto non_atomic2_end;
+rmb1:
+#ifndef NO_RMB
+ smp_rmb(i, j);
+#else
+ ooo_mem(i);
+#endif
+ goto rmb1_end;
+rmb2:
+#ifndef NO_RMB
+ smp_rmb(i, j);
+#else
+ ooo_mem(i);
+#endif
+ goto rmb2_end;
end:
skip;
}
#define WRITE_PROD_NONE (1 << 0)
-#define WRITE_PROC_FIRST_MB (1 << 1)
+#define WRITE_DATA (1 << 1)
+#define WRITE_PROC_WMB (1 << 2)
+#define WRITE_XCHG_PTR (1 << 3)
+
+#define WRITE_PROC_FIRST_MB (1 << 4)
/* first flip */
-#define WRITE_PROC_FIRST_READ_GP (1 << 2)
-#define WRITE_PROC_FIRST_WRITE_GP (1 << 3)
-#define WRITE_PROC_FIRST_WAIT (1 << 4)
-#define WRITE_PROC_FIRST_WAIT_LOOP (1 << 5)
+#define WRITE_PROC_FIRST_READ_GP (1 << 5)
+#define WRITE_PROC_FIRST_WRITE_GP (1 << 6)
+#define WRITE_PROC_FIRST_WAIT (1 << 7)
+#define WRITE_PROC_FIRST_WAIT_LOOP (1 << 8)
/* second flip */
-#define WRITE_PROC_SECOND_READ_GP (1 << 6)
-#define WRITE_PROC_SECOND_WRITE_GP (1 << 7)
-#define WRITE_PROC_SECOND_WAIT (1 << 8)
-#define WRITE_PROC_SECOND_WAIT_LOOP (1 << 9)
+#define WRITE_PROC_SECOND_READ_GP (1 << 9)
+#define WRITE_PROC_SECOND_WRITE_GP (1 << 10)
+#define WRITE_PROC_SECOND_WAIT (1 << 11)
+#define WRITE_PROC_SECOND_WAIT_LOOP (1 << 12)
-#define WRITE_PROC_SECOND_MB (1 << 10)
+#define WRITE_PROC_SECOND_MB (1 << 13)
+
+#define WRITE_FREE (1 << 14)
#define WRITE_PROC_ALL_TOKENS (WRITE_PROD_NONE \
+ | WRITE_DATA \
+ | WRITE_PROC_WMB \
+ | WRITE_XCHG_PTR \
| WRITE_PROC_FIRST_MB \
| WRITE_PROC_FIRST_READ_GP \
| WRITE_PROC_FIRST_WRITE_GP \
| WRITE_PROC_SECOND_READ_GP \
| WRITE_PROC_SECOND_WRITE_GP \
| WRITE_PROC_SECOND_WAIT \
- | WRITE_PROC_SECOND_MB)
+ | WRITE_PROC_SECOND_MB \
+ | WRITE_FREE)
-#define WRITE_PROC_ALL_TOKENS_CLEAR ((1 << 11) - 1)
+#define WRITE_PROC_ALL_TOKENS_CLEAR ((1 << 15) - 1)
+/*
+ * Mutexes are implied around writer execution. A single writer at a time.
+ */
active proctype urcu_writer()
{
byte i, j;
byte tmp, tmp2, tmpa;
- byte old_gen;
+ byte cur_data = 0, old_data, loop_nr = 0;
byte cur_gp_val = 0; /*
* Keep a local trace of the current parity so
* we don't add non-existing dependencies on the global
assert(get_pid() < NR_PROCS);
do
- :: (READ_CACHED_VAR(generation_ptr) < 5) ->
+ :: (loop_nr < 3) ->
#ifdef WRITER_PROGRESS
progress_writer1:
#endif
- ooo_mem(i);
- atomic {
- 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;
+ loop_nr = loop_nr + 1;
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROD_NONE);
+#ifdef NO_WMB
+ PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_WMB);
+#endif
+
#ifdef NO_MB
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_MB);
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_MB);
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_READ_GP);
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WRITE_GP);
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WAIT);
+ /* For single flip, we need to know the current parity */
+ cur_gp_val = cur_gp_val ^ RCU_GP_CTR_BIT;
#endif
do :: 1 ->
atomic {
if
+
:: CONSUME_TOKENS(proc_urcu_writer,
WRITE_PROD_NONE,
+ WRITE_DATA) ->
+ ooo_mem(i);
+ cur_data = (cur_data + 1) % SLAB_SIZE;
+ WRITE_CACHED_VAR(rcu_data[cur_data], WINE);
+ PRODUCE_TOKENS(proc_urcu_writer, WRITE_DATA);
+
+
+ :: CONSUME_TOKENS(proc_urcu_writer,
+ WRITE_DATA,
+ WRITE_PROC_WMB) ->
+ smp_wmb(i, j);
+ PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_WMB);
+
+ :: CONSUME_TOKENS(proc_urcu_writer,
+ WRITE_PROC_WMB,
+ WRITE_XCHG_PTR) ->
+ /* rcu_xchg_pointer() */
+ atomic {
+ old_data = READ_CACHED_VAR(rcu_ptr);
+ WRITE_CACHED_VAR(rcu_ptr, cur_data);
+ }
+ PRODUCE_TOKENS(proc_urcu_writer, WRITE_XCHG_PTR);
+
+ :: CONSUME_TOKENS(proc_urcu_writer,
+ WRITE_DATA | WRITE_PROC_WMB | WRITE_XCHG_PTR,
WRITE_PROC_FIRST_MB) ->
goto smp_mb_send1;
smp_mb_send1_end:
tmpa = READ_CACHED_VAR(urcu_gp_ctr);
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_FIRST_READ_GP);
:: CONSUME_TOKENS(proc_urcu_writer,
- WRITE_PROC_FIRST_MB | WRITE_PROC_FIRST_READ_GP,
+ WRITE_PROC_FIRST_MB | WRITE_PROC_WMB
+ | WRITE_PROC_FIRST_READ_GP,
WRITE_PROC_FIRST_WRITE_GP) ->
ooo_mem(i);
WRITE_CACHED_VAR(urcu_gp_ctr, tmpa ^ RCU_GP_CTR_BIT);
ooo_mem(i);
/* ONLY WAITING FOR READER 0 */
tmp2 = READ_CACHED_VAR(urcu_active_readers[0]);
- cur_gp_val = cur_gp_val ^ RCU_GP_CTR_BIT;
+#ifndef SINGLE_FLIP
+ /* In normal execution, we are always starting by
+ * waiting for the even parity.
+ */
+ cur_gp_val = RCU_GP_CTR_BIT;
+#endif
if
:: (tmp2 & RCU_GP_CTR_NEST_MASK)
&& ((tmp2 ^ cur_gp_val) & RCU_GP_CTR_BIT) ->
WRITE_PROC_FIRST_WRITE_GP
| WRITE_PROC_FIRST_READ_GP
| WRITE_PROC_FIRST_WAIT_LOOP
+ | WRITE_DATA | WRITE_PROC_WMB | WRITE_XCHG_PTR
| WRITE_PROC_FIRST_MB, /* can be reordered before/after flips */
0) ->
#ifndef GEN_ERROR_WRITER_PROGRESS
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_READ_GP);
:: CONSUME_TOKENS(proc_urcu_writer,
WRITE_PROC_FIRST_MB
+ | WRITE_PROC_WMB
| WRITE_PROC_FIRST_READ_GP
| WRITE_PROC_FIRST_WRITE_GP
| WRITE_PROC_SECOND_READ_GP,
ooo_mem(i);
/* ONLY WAITING FOR READER 0 */
tmp2 = READ_CACHED_VAR(urcu_active_readers[0]);
- cur_gp_val = cur_gp_val ^ RCU_GP_CTR_BIT;
if
:: (tmp2 & RCU_GP_CTR_NEST_MASK)
- && ((tmp2 ^ cur_gp_val) & RCU_GP_CTR_BIT) ->
+ && ((tmp2 ^ 0) & RCU_GP_CTR_BIT) ->
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WAIT_LOOP);
:: else ->
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_WAIT);
| WRITE_PROC_SECOND_READ_GP
| WRITE_PROC_FIRST_READ_GP
| WRITE_PROC_SECOND_WAIT_LOOP
+ | WRITE_DATA | WRITE_PROC_WMB | WRITE_XCHG_PTR
| WRITE_PROC_FIRST_MB, /* can be reordered before/after flips */
0) ->
#ifndef GEN_ERROR_WRITER_PROGRESS
| WRITE_PROC_SECOND_READ_GP
| WRITE_PROC_FIRST_WRITE_GP
| WRITE_PROC_SECOND_WRITE_GP
+ | WRITE_DATA | WRITE_PROC_WMB | WRITE_XCHG_PTR
| WRITE_PROC_FIRST_MB,
WRITE_PROC_SECOND_MB) ->
goto smp_mb_send4;
smp_mb_send4_end:
PRODUCE_TOKENS(proc_urcu_writer, WRITE_PROC_SECOND_MB);
+ :: CONSUME_TOKENS(proc_urcu_writer,
+ WRITE_XCHG_PTR
+ | WRITE_PROC_FIRST_WAIT
+ | WRITE_PROC_SECOND_WAIT
+ | WRITE_PROC_WMB /* No dependency on
+ * WRITE_DATA because we
+ * write to a
+ * different location. */
+ | WRITE_PROC_SECOND_MB
+ | WRITE_PROC_FIRST_MB,
+ WRITE_FREE) ->
+ WRITE_CACHED_VAR(rcu_data[old_data], POISON);
+ PRODUCE_TOKENS(proc_urcu_writer, WRITE_FREE);
+
:: CONSUME_TOKENS(proc_urcu_writer, WRITE_PROC_ALL_TOKENS, 0) ->
CLEAR_TOKENS(proc_urcu_writer, WRITE_PROC_ALL_TOKENS_CLEAR);
break;
fi;
}
od;
-
- write_lock = 0;
- /* free-up step, e.g., kfree(). */
- atomic {
- last_free_gen = old_gen;
- free_done = 1;
- }
+ /*
+ * Note : Promela model adds implicit serialization of the
+ * WRITE_FREE instruction. Normally, it would be permitted to
+ * spill on the next loop execution. Given the validation we do
+ * checks for the data entry read to be poisoned, it's ok if
+ * we do not check "late arriving" memory poisoning.
+ */
:: else -> break;
od;
/*
:: 1 ->
#ifdef WRITER_PROGRESS
progress_writer2:
+#endif
+#ifdef READER_PROGRESS
+ /*
+ * Make sure we don't block the reader's progress.
+ */
+ smp_mb_send(i, j, 5);
#endif
skip;
od;
atomic {
INIT_CACHED_VAR(urcu_gp_ctr, 1, j);
- INIT_CACHED_VAR(generation_ptr, 0, j);
+ INIT_CACHED_VAR(rcu_ptr, 0, j);
i = 0;
do
:: i < NR_READERS ->
INIT_CACHED_VAR(urcu_active_readers[i], 0, j);
- read_generation[i] = 1;
- data_access[i] = 0;
+ ptr_read_first[i] = 1;
+ ptr_read_second[i] = 1;
+ data_read_first[i] = WINE;
+ data_read_second[i] = WINE;
i++;
:: i >= NR_READERS -> break
od;
+ INIT_CACHED_VAR(rcu_data[0], WINE, j);
+ i = 1;
+ do
+ :: i < SLAB_SIZE ->
+ INIT_CACHED_VAR(rcu_data[i], POISON, j);
+ i++
+ :: i >= SLAB_SIZE -> break
+ od;
+
init_done = 1;
}
}
projects / urcu.git / blobdiff