h48

commit 1272e304b6367c7dd94d25acf88b2843adabb93a
parent 6f338b97a222dee630c9b13896cf443254667dfb
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Sat,  5 Oct 2024 23:00:08 +0200

Fix rare data race

I had some misconception about how _Atomic and const worked.
This means the previous commit (expected distribution) could
be incorrect.

Diffstat:
M
src/nissy.c
 | 
2
+-
M
src/solvers/h48/gendata_cocsep.h
 | 
5
+++--
M
src/solvers/h48/gendata_h48.h
 | 
45
++++++++++++++++++++++-----------------------
M
src/solvers/h48/solve.h
 | 
4
++--
M
src/solvers/h48/stats.h
 | 
4
++--

5 files changed, 30 insertions(+), 30 deletions(-)
diff --git a/src/nissy.c b/src/nissy.c
@@ -75,7 +75,7 @@ checkdata(const void *buf, const tableinfo_t *info)
 		getdistribution_cocsep(
 		    (uint32_t *)((char *)buf + INFOSIZE), distr);
 	} else if (!strncmp(info->solver, "h48", 3)) {
-		getdistribution_h48((uint8_t *)buf + INFOSIZE, distr,
+		getdistribution_h48((_Atomic uint8_t *)buf + INFOSIZE, distr,
 		    info->h48h, info->bits);
 	} else {
 		LOG("checkdata: unknown solver %s\n", info->solver);
diff --git a/src/solvers/h48/gendata_cocsep.h b/src/solvers/h48/gendata_cocsep.h
@@ -5,7 +5,8 @@ STATIC size_t gendata_cocsep(void *, uint64_t *, cube_t *);
 STATIC uint32_t gendata_cocsep_dfs(cocsep_dfs_arg_t *);
 STATIC void getdistribution_cocsep(const uint32_t *, uint64_t [static 21]);
 
-STATIC_INLINE int8_t get_h48_cdata(cube_t, const uint32_t *, uint32_t *);
+STATIC_INLINE int8_t get_h48_cdata(
+    cube_t, _Atomic const uint32_t *, uint32_t *);
 
 /*
 Each element of the cocsep table is a uint32_t used as follows:
@@ -158,7 +159,7 @@ set_visited(uint8_t *a, int64_t i)
 }
 
 STATIC_INLINE int8_t
-get_h48_cdata(cube_t cube, const uint32_t *cocsepdata, uint32_t *cdata)
+get_h48_cdata(cube_t cube, _Atomic const uint32_t *cocsepdata, uint32_t *cdata)
 {
 	int64_t coord;
 
diff --git a/src/solvers/h48/gendata_h48.h b/src/solvers/h48/gendata_h48.h
@@ -28,16 +28,16 @@ STATIC size_t gendata_h48k2_realcoord(gendata_h48_arg_t *);
 STATIC void gendata_h48k2_dfs(h48k2_dfs_arg_t *arg);
 STATIC void * gendata_h48k2_runthread(void *);
 STATIC tableinfo_t makeinfo_h48k2(gendata_h48_arg_t *);
-STATIC void getdistribution_h48(const uint8_t *,
+STATIC void getdistribution_h48(_Atomic const uint8_t *,
     uint64_t [static INFO_DISTRIBUTION_LEN], uint8_t, uint8_t);
 
-STATIC const uint32_t *get_cocsepdata_constptr(const void *);
-STATIC const uint8_t *get_h48data_constptr(const void *);
+STATIC _Atomic const uint32_t *get_cocsepdata_constptr(const void *);
+STATIC _Atomic const uint8_t *get_h48data_constptr(const void *);
 
-STATIC_INLINE uint8_t get_h48_pval(const uint8_t *, int64_t, uint8_t);
+STATIC_INLINE uint8_t get_h48_pval(_Atomic const uint8_t *, int64_t, uint8_t);
 STATIC_INLINE void set_h48_pval(_Atomic uint8_t *, int64_t, uint8_t, uint8_t);
 STATIC_INLINE uint8_t get_h48_bound(
-    cube_t, uint32_t, uint8_t, uint8_t, const uint8_t *);
+    cube_t, uint32_t, uint8_t, uint8_t, _Atomic const uint8_t *);
 
 size_t gendata_h48_derive(uint8_t, const void *, void *);
 
@@ -196,7 +196,7 @@ gendata_h48h0k4(gendata_h48_arg_t *arg)
 			pthread_join(thread[t], NULL);
 
 		for (i = 0, cc = 0; i < h48max; i++) {
-			val = get_h48_pval((uint8_t *)table, i, 4);
+			val = get_h48_pval(table, i, 4);
 			cc += val == d;
 		}
 
@@ -242,7 +242,7 @@ gendata_h48h0k4_runthread(void *arg)
          * Otherwise, scan all neighbors of unvisited coordinates.
 	 */
 	for (i = bfsarg->start; i < bfsarg->end; i++) {
-		c = get_h48_pval((uint8_t *)bfsarg->table, i, 4);
+		c = get_h48_pval(bfsarg->table, i, 4);
 
 		if ((bfsarg->depth < breakpoint && c != bfsarg->depth - 1) ||
 		    (bfsarg->depth >= breakpoint && c != 0xF))
@@ -252,7 +252,7 @@ gendata_h48h0k4_runthread(void *arg)
 		for (m = 0; m < 18; m++) {
 			moved = move(cube, m);
 			j = coord_h48(moved, bfsarg->cocsepdata, 0);
-			c = get_h48_pval((uint8_t *)bfsarg->table, j, 4);
+			c = get_h48_pval(bfsarg->table, j, 4);
 			if (bfsarg->depth < breakpoint) {
 				if (c <= bfsarg->depth)
 					continue;
@@ -356,7 +356,7 @@ gendata_h48k2(gendata_h48_arg_t *arg)
 	h48map_destroy(&shortcubes);
 
 	for (j = 0; j < H48_COORDMAX(arg->h); j++) {
-		t = get_h48_pval((uint8_t *)table, j, 2);
+		t = get_h48_pval(table, j, 2);
 		arg->info.distribution[t]++;
 	}
 
@@ -491,7 +491,7 @@ gendata_h48_mark(gendata_h48_mark_t *arg)
 
 	FOREACH_H48SIM(arg->cube, arg->cocsepdata, arg->selfsim,
 		coord = coord_h48(arg->cube, arg->cocsepdata, arg->h);
-		oldval = get_h48_pval((uint8_t *)arg->table, coord, arg->k);
+		oldval = get_h48_pval(arg->table, coord, arg->k);
 		newval = (uint8_t)MAX(arg->depth, 0);
 		if (newval < oldval) {
 			mutex = H48_INDEX(coord, arg->k) % CHUNKS;
@@ -515,7 +515,7 @@ gendata_h48k2_dfs_stop(cube_t cube, int8_t depth, h48k2_dfs_arg_t *arg)
 		coord = coord_h48(cube, arg->cocsepdata, arg->h);
 		mutex = H48_INDEX(coord, arg->k) % CHUNKS;
 		pthread_mutex_lock(arg->table_mutex[mutex]);
-		oldval = get_h48_pval((uint8_t *)arg->table, coord, arg->k);
+		oldval = get_h48_pval(arg->table, coord, arg->k);
 		pthread_mutex_unlock(arg->table_mutex[mutex]);
 		return oldval <= depth;
 	} else {
@@ -570,7 +570,7 @@ makeinfo_h48k2(gendata_h48_arg_t *arg)
 
 STATIC void
 getdistribution_h48(
-	const uint8_t *table,
+	_Atomic const uint8_t *table,
 	uint64_t distr[static INFO_DISTRIBUTION_LEN],
 	uint8_t h,
 	uint8_t k
@@ -587,20 +587,20 @@ getdistribution_h48(
 	}
 }
 
-STATIC const uint32_t *
+STATIC _Atomic const uint32_t *
 get_cocsepdata_constptr(const void *data)
 {
-	return (uint32_t *)((char *)data + INFOSIZE);
+	return (_Atomic uint32_t *)((char *)data + INFOSIZE);
 }
 
-STATIC const uint8_t *
+STATIC _Atomic const uint8_t *
 get_h48data_constptr(const void *data)
 {
-	return (uint8_t *)data + COCSEP_FULLSIZE + INFOSIZE;
+	return (_Atomic uint8_t *)data + COCSEP_FULLSIZE + INFOSIZE;
 }
 
 STATIC_INLINE uint8_t
-get_h48_pval(const uint8_t *table, int64_t i, uint8_t k)
+get_h48_pval(_Atomic const uint8_t *table, int64_t i, uint8_t k)
 {
 	return (table[H48_INDEX(i, k)] & H48_MASK(i, k)) >> H48_SHIFT(i, k);
 }
@@ -618,7 +618,7 @@ get_h48_bound(
 	uint32_t cdata,
 	uint8_t h,
 	uint8_t k,
-	const uint8_t *table
+	_Atomic const uint8_t *table
 ) {
 	int64_t coord;
 
@@ -631,7 +631,7 @@ gendata_h48_derive(uint8_t h, const void *fulltable, void *buf)
 {
 	size_t cocsepsize, h48size;
 	uint8_t val_full, val_derive;
-	const uint8_t *h48full;
+	_Atomic const uint8_t *h48full;
 	_Atomic uint8_t *h48derive;
 	int64_t i, j, h48max;
 	gendata_h48_arg_t arg;
@@ -672,7 +672,7 @@ gendata_h48_derive(uint8_t h, const void *fulltable, void *buf)
 		goto gendata_h48_derive_error;
 	}
 
-	h48full = (const uint8_t *)fulltable + cocsepsize + INFOSIZE;
+	h48full = (_Atomic const uint8_t *)fulltable + cocsepsize + INFOSIZE;
 	h48derive = (_Atomic uint8_t *)arg.h48buf + INFOSIZE;
 	memset(h48derive, 0xFF, H48_TABLESIZE(h, arg.k));
 	memset(arg.info.distribution, 0,
@@ -684,13 +684,12 @@ gendata_h48_derive(uint8_t h, const void *fulltable, void *buf)
 			LOG("Processing %" PRId64 "th coordinate\n", i);
 		j = i >> (int64_t)(fulltableinfo.h48h - h);
 		val_full = get_h48_pval(h48full, i, arg.k);
-		val_derive = get_h48_pval((uint8_t *)h48derive, j, arg.k);
+		val_derive = get_h48_pval(h48derive, j, arg.k);
 		set_h48_pval(
 		    h48derive, j, arg.k, MIN(val_full, val_derive));
 	}
 
-	getdistribution_h48(
-	    (uint8_t *)h48derive, arg.info.distribution, h, arg.k);
+	getdistribution_h48(h48derive, arg.info.distribution, h, arg.k);
 
 	if (!writetableinfo(&arg.info, arg.h48buf)) {
 		LOG("gendata_h48_derive: could not write info for table\n");
diff --git a/src/solvers/h48/solve.h b/src/solvers/h48/solve.h
@@ -8,8 +8,8 @@ typedef struct {
 	int64_t maxsolutions;
 	uint8_t h;
 	uint8_t k;
-	const uint32_t *cocsepdata;
-	const uint8_t *h48data;
+	_Atomic const uint32_t *cocsepdata;
+	_Atomic const uint8_t *h48data;
 	char **nextsol;
 	uint8_t nissbranch;
 	int8_t npremoves;
diff --git a/src/solvers/h48/stats.h b/src/solvers/h48/stats.h
@@ -10,8 +10,8 @@ typedef struct {
 	int8_t nmoves;
 	int8_t depth;
 	uint8_t moves[MAXLEN];
-	const uint32_t *cocsepdata;
-	const uint8_t *h48data;
+	_Atomic const uint32_t *cocsepdata;
+	_Atomic const uint8_t *h48data;
 	char *s;
 } dfsarg_solveh48stats_t;