[dpdk-dev] [PATCH v4 04/14] acl: remove library constructor

[Konstantin Ananyev <konstantin.ananyev@intel.com>]

Right now ACL library determines best possible (default) classify method
on a given platform with specilal constructor function rte_acl_init().
This patch makes the following changes:
 - Move selection of default classify method into a separate private
   function and call it for each ACL context creation (rte_acl_create()).
 - Remove library constructor function
 - Make rte_acl_set_ctx_classify() to check that requested algorithm
   is supported on given platform.

The purpose of these changes to improve and simplify algorithm selection
process and prepare ACL library to be integrated with:
add max SIMD bitwidth to EAL
(https://patches.dpdk.org/project/dpdk/list/?series=11831)
patch-set

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
---
 lib/librte_acl/rte_acl.c | 166 ++++++++++++++++++++++++++++++---------
 lib/librte_acl/rte_acl.h |   1 +
 2 files changed, 132 insertions(+), 35 deletions(-)

diff --git a/lib/librte_acl/rte_acl.c b/lib/librte_acl/rte_acl.c
index 715b023592..863549a38b 100644
--- a/lib/librte_acl/rte_acl.c
+++ b/lib/librte_acl/rte_acl.c
@@ -79,57 +79,153 @@ static const rte_acl_classify_t classify_fns[] = {
 	[RTE_ACL_CLASSIFY_ALTIVEC] = rte_acl_classify_altivec,
 };
 
-/* by default, use always available scalar code path. */
-static enum rte_acl_classify_alg rte_acl_default_classify =
-	RTE_ACL_CLASSIFY_SCALAR;
+/*
+ * Helper function for acl_check_alg.
+ * Check support for ARM specific classify methods.
+ */
+static int
+acl_check_alg_arm(enum rte_acl_classify_alg alg)
+{
+	if (alg == RTE_ACL_CLASSIFY_NEON) {
+#if defined(RTE_ARCH_ARM64)
+		return 0;
+#elif defined(RTE_ARCH_ARM)
+		if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_NEON))
+			return 0;
+		return -ENOTSUP;
+#else
+		return -ENOTSUP;
+#endif
+	}
+
+	return -EINVAL;
+}
 
-static void
-rte_acl_set_default_classify(enum rte_acl_classify_alg alg)
+/*
+ * Helper function for acl_check_alg.
+ * Check support for PPC specific classify methods.
+ */
+static int
+acl_check_alg_ppc(enum rte_acl_classify_alg alg)
 {
-	rte_acl_default_classify = alg;
+	if (alg == RTE_ACL_CLASSIFY_ALTIVEC) {
+#if defined(RTE_ARCH_PPC_64)
+		return 0;
+#else
+		return -ENOTSUP;
+#endif
+	}
+
+	return -EINVAL;
 }
 
-extern int
-rte_acl_set_ctx_classify(struct rte_acl_ctx *ctx, enum rte_acl_classify_alg alg)
+/*
+ * Helper function for acl_check_alg.
+ * Check support for x86 specific classify methods.
+ */
+static int
+acl_check_alg_x86(enum rte_acl_classify_alg alg)
 {
-	if (ctx == NULL || (uint32_t)alg >= RTE_DIM(classify_fns))
-		return -EINVAL;
+	if (alg == RTE_ACL_CLASSIFY_AVX2) {
+#ifdef CC_AVX2_SUPPORT
+		if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_AVX2))
+			return 0;
+#endif
+		return -ENOTSUP;
+	}
 
-	ctx->alg = alg;
-	return 0;
+	if (alg == RTE_ACL_CLASSIFY_SSE) {
+#ifdef RTE_ARCH_X86
+		if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE4_1))
+			return 0;
+#endif
+		return -ENOTSUP;
+	}
+
+	return -EINVAL;
 }
 
 /*
- * Select highest available classify method as default one.
- * Note that CLASSIFY_AVX2 should be set as a default only
- * if both conditions are met:
- * at build time compiler supports AVX2 and target cpu supports AVX2.
+ * Check if input alg is supported by given platform/binary.
+ * Note that both conditions should be met:
+ * - at build time compiler supports ISA used by given methods
+ * - at run time target cpu supports necessary ISA.
  */
-RTE_INIT(rte_acl_init)
+static int
+acl_check_alg(enum rte_acl_classify_alg alg)
 {
-	enum rte_acl_classify_alg alg = RTE_ACL_CLASSIFY_DEFAULT;
+	switch (alg) {
+	case RTE_ACL_CLASSIFY_NEON:
+		return acl_check_alg_arm(alg);
+	case RTE_ACL_CLASSIFY_ALTIVEC:
+		return acl_check_alg_ppc(alg);
+	case RTE_ACL_CLASSIFY_AVX2:
+	case RTE_ACL_CLASSIFY_SSE:
+		return acl_check_alg_x86(alg);
+	/* scalar method is supported on all platforms */
+	case RTE_ACL_CLASSIFY_SCALAR:
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
 
-#if defined(RTE_ARCH_ARM64)
-	alg =  RTE_ACL_CLASSIFY_NEON;
-#elif defined(RTE_ARCH_ARM)
-	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_NEON))
-		alg =  RTE_ACL_CLASSIFY_NEON;
+/*
+ * Get preferred alg for given platform.
+ */
+static enum rte_acl_classify_alg
+acl_get_best_alg(void)
+{
+	/*
+	 * array of supported methods for each platform.
+	 * Note that order is important - from most to less preferable.
+	 */
+	static const enum rte_acl_classify_alg alg[] = {
+#if defined(RTE_ARCH_ARM)
+		RTE_ACL_CLASSIFY_NEON,
 #elif defined(RTE_ARCH_PPC_64)
-	alg = RTE_ACL_CLASSIFY_ALTIVEC;
-#else
-#ifdef CC_AVX2_SUPPORT
-	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_AVX2))
-		alg = RTE_ACL_CLASSIFY_AVX2;
-	else if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE4_1))
-#else
-	if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE4_1))
+		RTE_ACL_CLASSIFY_ALTIVEC,
+#elif defined(RTE_ARCH_X86)
+		RTE_ACL_CLASSIFY_AVX2,
+		RTE_ACL_CLASSIFY_SSE,
 #endif
-		alg = RTE_ACL_CLASSIFY_SSE;
+		RTE_ACL_CLASSIFY_SCALAR,
+	};
 
-#endif
-	rte_acl_set_default_classify(alg);
+	uint32_t i;
+
+	/* find best possible alg */
+	for (i = 0; i != RTE_DIM(alg) && acl_check_alg(alg[i]) != 0; i++)
+		;
+
+	/* we always have to find something suitable */
+	RTE_VERIFY(i != RTE_DIM(alg));
+	return alg[i];
+}
+
+extern int
+rte_acl_set_ctx_classify(struct rte_acl_ctx *ctx, enum rte_acl_classify_alg alg)
+{
+	int32_t rc;
+
+	/* formal parameters check */
+	if (ctx == NULL || (uint32_t)alg >= RTE_DIM(classify_fns))
+		return -EINVAL;
+
+	/* user asked us to select the *best* one */
+	if (alg == RTE_ACL_CLASSIFY_DEFAULT)
+		alg = acl_get_best_alg();
+
+	/* check that given alg is supported */
+	rc = acl_check_alg(alg);
+	if (rc != 0)
+		return rc;
+
+	ctx->alg = alg;
+	return 0;
 }
 
+
 int
 rte_acl_classify_alg(const struct rte_acl_ctx *ctx, const uint8_t **data,
 	uint32_t *results, uint32_t num, uint32_t categories,
@@ -262,7 +358,7 @@ rte_acl_create(const struct rte_acl_param *param)
 		ctx->max_rules = param->max_rule_num;
 		ctx->rule_sz = param->rule_size;
 		ctx->socket_id = param->socket_id;
-		ctx->alg = rte_acl_default_classify;
+		ctx->alg = acl_get_best_alg();
 		strlcpy(ctx->name, param->name, sizeof(ctx->name));
 
 		te->data = (void *) ctx;
diff --git a/lib/librte_acl/rte_acl.h b/lib/librte_acl/rte_acl.h
index b814423a63..3999f15ded 100644
--- a/lib/librte_acl/rte_acl.h
+++ b/lib/librte_acl/rte_acl.h
@@ -329,6 +329,7 @@ rte_acl_classify_alg(const struct rte_acl_ctx *ctx,
  *   existing algorithm, and that it could be run on the given CPU.
  * @return
  *   - -EINVAL if the parameters are invalid.
+ *   - -ENOTSUP requested algorithm is not supported by given platform.
  *   - Zero if operation completed successfully.
  */
 extern int
-- 
2.17.1