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* [PATCH] fib: implement RCU rule reclamation
@ 2024-09-06 17:09 Vladimir Medvedkin
  2024-09-27 22:12 ` Robin Jarry
  0 siblings, 1 reply; 3+ messages in thread
From: Vladimir Medvedkin @ 2024-09-06 17:09 UTC (permalink / raw)
  To: dev; +Cc: rjarry, ruifeng.wang, honnappa.nagarahalli

Currently, for DIR24-8 algorithm, the tbl8 group is freed even though the
readers might be using the tbl8 group entries. The freed tbl8 group can
be reallocated quickly. As a result, lookup may be performed incorrectly.

To address that, RCU QSBR is integrated for safe tbl8 group reclamation.

Signed-off-by: Vladimir Medvedkin <vladimir.medvedkin@intel.com>
---
 lib/fib/dir24_8.c   | 104 +++++++++++++++++++++++++++++++++++++++-----
 lib/fib/dir24_8.h   |   9 ++++
 lib/fib/meson.build |   1 +
 lib/fib/rte_fib.c   |  11 +++++
 lib/fib/rte_fib.h   |  50 ++++++++++++++++++++-
 lib/fib/version.map |   7 +++
 6 files changed, 171 insertions(+), 11 deletions(-)

diff --git a/lib/fib/dir24_8.c b/lib/fib/dir24_8.c
index c739e92304..f884b02d2c 100644
--- a/lib/fib/dir24_8.c
+++ b/lib/fib/dir24_8.c
@@ -14,6 +14,7 @@
 #include <rte_rib.h>
 #include <rte_fib.h>
 #include "dir24_8.h"
+#include "fib_log.h"
 
 #ifdef CC_DIR24_8_AVX512_SUPPORT
 
@@ -176,6 +177,13 @@ tbl8_alloc(struct dir24_8_tbl *dp, uint64_t nh)
 	uint8_t	*tbl8_ptr;
 
 	tbl8_idx = tbl8_get_idx(dp);
+	if ((tbl8_idx == -ENOSPC) && dp->dq != NULL) {
+		/* If there are no tbl8 groups try to reclaim one. */
+		if (rte_rcu_qsbr_dq_reclaim(dp->dq, 1,
+				NULL, NULL, NULL) == 0)
+			tbl8_idx = tbl8_get_idx(dp);
+	}
+
 	if (tbl8_idx < 0)
 		return tbl8_idx;
 	tbl8_ptr = (uint8_t *)dp->tbl8 +
@@ -189,6 +197,27 @@ tbl8_alloc(struct dir24_8_tbl *dp, uint64_t nh)
 	return tbl8_idx;
 }
 
+static void
+tbl8_cleanup_and_free(struct dir24_8_tbl *dp, uint64_t tbl8_idx)
+{
+	uint8_t *ptr = (uint8_t *)dp->tbl8 +
+		(tbl8_idx * DIR24_8_TBL8_GRP_NUM_ENT << dp->nh_sz);
+
+	memset(ptr, 0, DIR24_8_TBL8_GRP_NUM_ENT << dp->nh_sz);
+	tbl8_free_idx(dp, tbl8_idx);
+	dp->cur_tbl8s--;
+}
+
+static void
+__rcu_qsbr_free_resource(void *p, void *data, unsigned int n)
+{
+	struct dir24_8_tbl *dp = p;
+	uint64_t tbl8_idx = *(uint64_t *)data;
+	RTE_SET_USED(n);
+
+	tbl8_cleanup_and_free(dp, tbl8_idx);
+}
+
 static void
 tbl8_recycle(struct dir24_8_tbl *dp, uint32_t ip, uint64_t tbl8_idx)
 {
@@ -210,8 +239,6 @@ tbl8_recycle(struct dir24_8_tbl *dp, uint32_t ip, uint64_t tbl8_idx)
 		}
 		((uint8_t *)dp->tbl24)[ip >> 8] =
 			nh & ~DIR24_8_EXT_ENT;
-		for (i = 0; i < DIR24_8_TBL8_GRP_NUM_ENT; i++)
-			ptr8[i] = 0;
 		break;
 	case RTE_FIB_DIR24_8_2B:
 		ptr16 = &((uint16_t *)dp->tbl8)[tbl8_idx *
@@ -223,8 +250,6 @@ tbl8_recycle(struct dir24_8_tbl *dp, uint32_t ip, uint64_t tbl8_idx)
 		}
 		((uint16_t *)dp->tbl24)[ip >> 8] =
 			nh & ~DIR24_8_EXT_ENT;
-		for (i = 0; i < DIR24_8_TBL8_GRP_NUM_ENT; i++)
-			ptr16[i] = 0;
 		break;
 	case RTE_FIB_DIR24_8_4B:
 		ptr32 = &((uint32_t *)dp->tbl8)[tbl8_idx *
@@ -236,8 +261,6 @@ tbl8_recycle(struct dir24_8_tbl *dp, uint32_t ip, uint64_t tbl8_idx)
 		}
 		((uint32_t *)dp->tbl24)[ip >> 8] =
 			nh & ~DIR24_8_EXT_ENT;
-		for (i = 0; i < DIR24_8_TBL8_GRP_NUM_ENT; i++)
-			ptr32[i] = 0;
 		break;
 	case RTE_FIB_DIR24_8_8B:
 		ptr64 = &((uint64_t *)dp->tbl8)[tbl8_idx *
@@ -249,12 +272,20 @@ tbl8_recycle(struct dir24_8_tbl *dp, uint32_t ip, uint64_t tbl8_idx)
 		}
 		((uint64_t *)dp->tbl24)[ip >> 8] =
 			nh & ~DIR24_8_EXT_ENT;
-		for (i = 0; i < DIR24_8_TBL8_GRP_NUM_ENT; i++)
-			ptr64[i] = 0;
 		break;
 	}
-	tbl8_free_idx(dp, tbl8_idx);
-	dp->cur_tbl8s--;
+
+	if (dp->v == NULL)
+		tbl8_cleanup_and_free(dp, tbl8_idx);
+	else if (dp->rcu_mode == RTE_FIB_QSBR_MODE_SYNC) {
+		rte_rcu_qsbr_synchronize(dp->v,
+			RTE_QSBR_THRID_INVALID);
+		tbl8_cleanup_and_free(dp, tbl8_idx);
+	} else { /* RTE_FIB_QSBR_MODE_DQ */
+		if (rte_rcu_qsbr_dq_enqueue(dp->dq,
+				(void *)&tbl8_idx))
+			FIB_LOG(ERR, "Failed to push QSBR FIFO");
+	}
 }
 
 static int
@@ -569,7 +600,60 @@ dir24_8_free(void *p)
 {
 	struct dir24_8_tbl *dp = (struct dir24_8_tbl *)p;
 
+	if (dp->dq != NULL)
+		rte_rcu_qsbr_dq_delete(dp->dq);
+
 	rte_free(dp->tbl8_idxes);
 	rte_free(dp->tbl8);
 	rte_free(dp);
 }
+
+int
+dir24_8_rcu_qsbr_add(struct dir24_8_tbl *dp, struct rte_fib_rcu_config *cfg,
+	const char *name)
+{
+	struct rte_rcu_qsbr_dq_parameters params = {0};
+	char rcu_dq_name[RTE_RCU_QSBR_DQ_NAMESIZE];
+
+	if (dp == NULL || cfg == NULL) {
+		rte_errno = EINVAL;
+		return 1;
+	}
+
+	if (dp->v != NULL) {
+		rte_errno = EEXIST;
+		return 1;
+	}
+
+	if (cfg->mode == RTE_FIB_QSBR_MODE_SYNC) {
+		/* No other things to do. */
+	} else if (cfg->mode == RTE_FIB_QSBR_MODE_DQ) {
+		/* Init QSBR defer queue. */
+		snprintf(rcu_dq_name, sizeof(rcu_dq_name),
+				"FIB_RCU_%s", name);
+		params.name = rcu_dq_name;
+		params.size = cfg->dq_size;
+		if (params.size == 0)
+			params.size = RTE_FIB_RCU_DQ_RECLAIM_SZ;
+		params.trigger_reclaim_limit = cfg->reclaim_thd;
+		params.max_reclaim_size = cfg->reclaim_max;
+		if (params.max_reclaim_size == 0)
+			params.max_reclaim_size = RTE_FIB_RCU_DQ_RECLAIM_MAX;
+		params.esize = sizeof(uint64_t);
+		params.free_fn = __rcu_qsbr_free_resource;
+		params.p = dp;
+		params.v = cfg->v;
+		dp->dq = rte_rcu_qsbr_dq_create(&params);
+		if (dp->dq == NULL) {
+			FIB_LOG(ERR, "LPM defer queue creation failed");
+			return 1;
+		}
+	} else {
+		rte_errno = EINVAL;
+		return 1;
+	}
+	dp->rcu_mode = cfg->mode;
+	dp->v = cfg->v;
+
+	return 0;
+}
\ No newline at end of file
diff --git a/lib/fib/dir24_8.h b/lib/fib/dir24_8.h
index 7125049f15..08fd818ce4 100644
--- a/lib/fib/dir24_8.h
+++ b/lib/fib/dir24_8.h
@@ -10,6 +10,7 @@
 
 #include <rte_prefetch.h>
 #include <rte_branch_prediction.h>
+#include <rte_rcu_qsbr.h>
 
 /**
  * @file
@@ -30,6 +31,10 @@ struct dir24_8_tbl {
 	uint32_t	rsvd_tbl8s;	/**< Number of reserved tbl8s */
 	uint32_t	cur_tbl8s;	/**< Current number of tbl8s */
 	enum rte_fib_dir24_8_nh_sz	nh_sz;	/**< Size of nexthop entry */
+	/* RCU config. */
+	enum rte_fib_qsbr_mode rcu_mode;/* Blocking, defer queue. */
+	struct rte_rcu_qsbr *v;		/* RCU QSBR variable. */
+	struct rte_rcu_qsbr_dq *dq;	/* RCU QSBR defer queue. */
 	uint64_t	def_nh;		/**< Default next hop */
 	uint64_t	*tbl8;		/**< tbl8 table. */
 	uint64_t	*tbl8_idxes;	/**< bitmap containing free tbl8 idxes*/
@@ -250,4 +255,8 @@ int
 dir24_8_modify(struct rte_fib *fib, uint32_t ip, uint8_t depth,
 	uint64_t next_hop, int op);
 
+int
+dir24_8_rcu_qsbr_add(struct dir24_8_tbl *dp, struct rte_fib_rcu_config *cfg,
+	const char *name);
+
 #endif /* _DIR24_8_H_ */
diff --git a/lib/fib/meson.build b/lib/fib/meson.build
index 6795f41a0a..1895f37050 100644
--- a/lib/fib/meson.build
+++ b/lib/fib/meson.build
@@ -11,6 +11,7 @@ endif
 sources = files('rte_fib.c', 'rte_fib6.c', 'dir24_8.c', 'trie.c')
 headers = files('rte_fib.h', 'rte_fib6.h')
 deps += ['rib']
+deps += ['rcu']
 
 # compile AVX512 version if:
 # we are building 64-bit binary AND binutils can generate proper code
diff --git a/lib/fib/rte_fib.c b/lib/fib/rte_fib.c
index 4f9fba5a4f..f1b73d64cb 100644
--- a/lib/fib/rte_fib.c
+++ b/lib/fib/rte_fib.c
@@ -338,3 +338,14 @@ rte_fib_select_lookup(struct rte_fib *fib,
 		return -EINVAL;
 	}
 }
+
+int
+rte_fib_rcu_qsbr_add(struct rte_fib *fib, struct rte_fib_rcu_config *cfg)
+{
+	switch (fib->type) {
+	case RTE_FIB_DIR24_8:
+	        return dir24_8_rcu_qsbr_add(fib->dp, cfg, fib->name);
+	default:
+	        return -ENOTSUP;
+	}
+}
\ No newline at end of file
diff --git a/lib/fib/rte_fib.h b/lib/fib/rte_fib.h
index d7a5aafe53..346eb7f149 100644
--- a/lib/fib/rte_fib.h
+++ b/lib/fib/rte_fib.h
@@ -16,7 +16,7 @@
  */
 
 #include <stdint.h>
-
+#include <rte_rcu_qsbr.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -28,6 +28,19 @@ struct rte_rib;
 /** Maximum depth value possible for IPv4 FIB. */
 #define RTE_FIB_MAXDEPTH	32
 
+/** @internal Default RCU defer queue entries to reclaim in one go. */
+#define RTE_FIB_RCU_DQ_RECLAIM_MAX	16
+/** @internal Default RCU defer queue size. */
+#define RTE_FIB_RCU_DQ_RECLAIM_SZ	128
+
+/** RCU reclamation modes */
+enum rte_fib_qsbr_mode {
+	/** Create defer queue for reclaim. */
+	RTE_FIB_QSBR_MODE_DQ = 0,
+	/** Use blocking mode reclaim. No defer queue created. */
+	RTE_FIB_QSBR_MODE_SYNC
+};
+
 /** Type of FIB struct */
 enum rte_fib_type {
 	RTE_FIB_DUMMY,		/**< RIB tree based FIB */
@@ -89,6 +102,22 @@ struct rte_fib_conf {
 	};
 };
 
+/** FIB RCU QSBR configuration structure. */
+struct rte_fib_rcu_config {
+	struct rte_rcu_qsbr *v;	/* RCU QSBR variable. */
+	/* Mode of RCU QSBR. RTE_FIB_QSBR_MODE_xxx
+	 * '0' for default: create defer queue for reclaim.
+	 */
+	enum rte_fib_qsbr_mode mode;
+	uint32_t dq_size;	/* RCU defer queue size.
+				 * default: RTE_FIB_RCU_DQ_RECLAIM_SZ.
+				 */
+	uint32_t reclaim_thd;	/* Threshold to trigger auto reclaim. */
+	uint32_t reclaim_max;	/* Max entries to reclaim in one go.
+				 * default: RTE_FIB_RCU_DQ_RECLAIM_MAX.
+				 */
+};
+
 /**
  * Create FIB
  *
@@ -219,6 +248,25 @@ rte_fib_get_rib(struct rte_fib *fib);
 int
 rte_fib_select_lookup(struct rte_fib *fib, enum rte_fib_lookup_type type);
 
+/**
+ * Associate RCU QSBR variable with a FIB object.
+ *
+ * @param fib
+ *   the fib object to add RCU QSBR
+ * @param cfg
+ *   RCU QSBR configuration
+ * @return
+ *   On success - 0
+ *   On error - 1 with error code set in rte_errno.
+ *   Possible rte_errno codes are:
+ *   - EINVAL - invalid pointer
+ *   - EEXIST - already added QSBR
+ *   - ENOMEM - memory allocation failure
+ *   - ENOTSUP - not supported by configured dataplane algorithm
+ */
+__rte_experimental
+int rte_fib_rcu_qsbr_add(struct rte_fib *fib, struct rte_fib_rcu_config *cfg);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/fib/version.map b/lib/fib/version.map
index c6d2769611..df8f113df3 100644
--- a/lib/fib/version.map
+++ b/lib/fib/version.map
@@ -22,3 +22,10 @@ DPDK_25 {
 
 	local: *;
 };
+
+EXPERIMENTAL {
+	global:
+
+	# added in 24.11
+	rte_fib_rcu_qsbr_add;
+};
-- 
2.34.1


^ permalink raw reply	[flat|nested] 3+ messages in thread
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2024-09-06 17:09 [PATCH] fib: implement RCU rule reclamation Vladimir Medvedkin
2024-09-27 22:12 ` Robin Jarry
2024-09-27 23:52   ` David Marchand

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