[RFC 0/6] Packet capture fixes

[RFC 0/6] Packet capture fixes

[Stephen Hemminger]

This patch series addresses the problem of packet capture when
the secondary process is sending/receiving by using the same
mechanism as hot plug.  It also fixes some bugs on shutdown
of dumpcap (and pdump).

In draft form at this point, works but needs more testing.

Stephen Hemminger (6):
  dumpcap: handle primary process exit
  pdump: handle primary process exit
  pdump: fix races in callbacks
  dumpcap: handle pdump requests from primary
  pdump: handle pdump requests from primary
  pdump: forward callback enable to secondary

 app/dumpcap/main.c    |  14 +++
 app/pdump/main.c      |  16 ++-
 lib/pdump/rte_pdump.c | 261 +++++++++++++++++++++++++++++++++++++-----
 3 files changed, 256 insertions(+), 35 deletions(-)

-- 
2.47.2

[RFC 1/6] dumpcap: handle primary process exit

[Stephen Hemminger]

If primary process exits, then it is not possible (or needed)
to cleanup resources. Instead just exit after closing the
capture file.

Bugzilla ID: 1760
Fixes: cbb44143be74 ("app/dumpcap: add new packet capture application")
Cc: stable@dpdk.org

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 app/dumpcap/main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/app/dumpcap/main.c b/app/dumpcap/main.c
index 3d3c0dbc66..7b19c830b5 100644
--- a/app/dumpcap/main.c
+++ b/app/dumpcap/main.c
@@ -1058,6 +1058,10 @@ int main(int argc, char **argv)
 	else
 		pcap_dump_close(out.dumper);
 
+	/* If primary has exited, do not try and communicate with it */
+	if (!rte_eal_primary_proc_alive(NULL))
+		return 0;
+
 	cleanup_pdump_resources();
 
 	rte_ring_free(r);
-- 
2.47.2

[RFC 2/6] pdump: handle primary process exit

[Stephen Hemminger]

If primary process exits, then it is not possible (or needed)
to cleanup resources. Instead just exit after closing the
capture file.

Bugzilla ID: 1760
Fixes: a99a311ba101 ("app/pdump: exit with primary process")
Cc: stable@dpdk.org

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 app/pdump/main.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/app/pdump/main.c b/app/pdump/main.c
index fa85859703..1741d7e709 100644
--- a/app/pdump/main.c
+++ b/app/pdump/main.c
@@ -1028,13 +1028,15 @@ main(int argc, char **argv)
 	dump_packets();
 
 	disable_primary_monitor();
-	cleanup_pdump_resources();
+
 	/* dump debug stats */
 	print_pdump_stats();
 
-	ret = rte_eal_cleanup();
-	if (ret)
-		printf("Error from rte_eal_cleanup(), %d\n", ret);
+	/* If primary has exited, do not try and communicate with it */
+	if (!rte_eal_primary_proc_alive(NULL))
+		return 0;
 
-	return 0;
+	cleanup_pdump_resources();
+
+	return rte_eal_cleanup() ? EXIT_FAILURE : 0;
 }
-- 
2.47.2

[RFC 3/6] pdump: fix races in callbacks

[Stephen Hemminger]

The pdump callback can race with other cpu's in the datapath.
Handle this by using reference counts and LSB in manner
similar to seqcount and bpf code.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/pdump/rte_pdump.c | 48 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/lib/pdump/rte_pdump.c b/lib/pdump/rte_pdump.c
index ba75b828f2..bfd63fa8c2 100644
--- a/lib/pdump/rte_pdump.c
+++ b/lib/pdump/rte_pdump.c
@@ -12,6 +12,7 @@
 #include <rte_memzone.h>
 #include <rte_errno.h>
 #include <rte_string_fns.h>
+#include <rte_pause.h>
 #include <rte_pcapng.h>
 
 #include "rte_pdump.h"
@@ -62,6 +63,7 @@ static struct pdump_rxtx_cbs {
 	const struct rte_bpf *filter;
 	enum pdump_version ver;
 	uint32_t snaplen;
+	RTE_ATOMIC(uint32_t) use_count;
 } rx_cbs[RTE_MAX_ETHPORTS][RTE_MAX_QUEUES_PER_PORT],
 tx_cbs[RTE_MAX_ETHPORTS][RTE_MAX_QUEUES_PER_PORT];
 
@@ -78,6 +80,36 @@ static struct {
 	const struct rte_memzone *mz;
 } *pdump_stats;
 
+static void
+pdump_cb_wait(struct pdump_rxtx_cbs *cbs)
+{
+	/* make sure the data loads happens before the use count load */
+	rte_atomic_thread_fence(rte_memory_order_acquire);
+
+	/* wait until use_count is even (not in use) */
+	RTE_WAIT_UNTIL_MASKED(&cbs->use_count, 1, ==, 0, rte_memory_order_relaxed);
+}
+
+static __rte_always_inline void
+pdump_cb_hold(struct pdump_rxtx_cbs *cbs)
+{
+	uint32_t count = cbs->use_count + 1;
+
+	rte_atomic_store_explicit(&cbs->use_count, count, rte_memory_order_relaxed);
+
+	/* prevent stores after this from happening before the use_count update */
+	rte_atomic_thread_fence(rte_memory_order_release);
+}
+
+static __rte_always_inline void
+pdump_cb_release(struct pdump_rxtx_cbs *cbs)
+{
+	uint32_t count = cbs->use_count + 1;
+
+	/* Synchronizes-with the load acquire in pdump_cb_wait */
+	rte_atomic_store_explicit(&cbs->use_count, count, rte_memory_order_release);
+}
+
 /* Create a clone of mbuf to be placed into ring. */
 static void
 pdump_copy(uint16_t port_id, uint16_t queue,
@@ -146,11 +178,14 @@ pdump_rx(uint16_t port, uint16_t queue,
 	struct rte_mbuf **pkts, uint16_t nb_pkts,
 	uint16_t max_pkts __rte_unused, void *user_params)
 {
-	const struct pdump_rxtx_cbs *cbs = user_params;
+	struct pdump_rxtx_cbs *cbs = user_params;
 	struct rte_pdump_stats *stats = &pdump_stats->rx[port][queue];
 
+	pdump_cb_hold(cbs);
 	pdump_copy(port, queue, RTE_PCAPNG_DIRECTION_IN,
 		   pkts, nb_pkts, cbs, stats);
+	pdump_cb_release(cbs);
+
 	return nb_pkts;
 }
 
@@ -158,14 +193,18 @@ static uint16_t
 pdump_tx(uint16_t port, uint16_t queue,
 		struct rte_mbuf **pkts, uint16_t nb_pkts, void *user_params)
 {
-	const struct pdump_rxtx_cbs *cbs = user_params;
+	struct pdump_rxtx_cbs *cbs = user_params;
 	struct rte_pdump_stats *stats = &pdump_stats->tx[port][queue];
 
+	pdump_cb_hold(cbs);
 	pdump_copy(port, queue, RTE_PCAPNG_DIRECTION_OUT,
 		   pkts, nb_pkts, cbs, stats);
+	pdump_cb_release(cbs);
+
 	return nb_pkts;
 }
 
+
 static int
 pdump_register_rx_callbacks(enum pdump_version ver,
 			    uint16_t end_q, uint16_t port, uint16_t queue,
@@ -186,6 +225,7 @@ pdump_register_rx_callbacks(enum pdump_version ver,
 					port, qid);
 				return -EEXIST;
 			}
+			cbs->use_count = 0;
 			cbs->ver = ver;
 			cbs->ring = ring;
 			cbs->mp = mp;
@@ -218,6 +258,7 @@ pdump_register_rx_callbacks(enum pdump_version ver,
 					-ret);
 				return ret;
 			}
+			pdump_cb_wait(cbs);
 			cbs->cb = NULL;
 		}
 	}
@@ -246,6 +287,7 @@ pdump_register_tx_callbacks(enum pdump_version ver,
 					port, qid);
 				return -EEXIST;
 			}
+			cbs->use_count = 0;
 			cbs->ver = ver;
 			cbs->ring = ring;
 			cbs->mp = mp;
@@ -277,6 +319,8 @@ pdump_register_tx_callbacks(enum pdump_version ver,
 					-ret);
 				return ret;
 			}
+
+			pdump_cb_wait(cbs);
 			cbs->cb = NULL;
 		}
 	}
-- 
2.47.2

[RFC 4/6] dumpcap: handle pdump requests from primary

[Stephen Hemminger]

The primary process will start to notify all secondary processes
about pdump changes. The dumpcap secondary process can just call
rte_pdump_init() and it take care of that.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 app/dumpcap/main.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/app/dumpcap/main.c b/app/dumpcap/main.c
index 7b19c830b5..c734fc7b9d 100644
--- a/app/dumpcap/main.c
+++ b/app/dumpcap/main.c
@@ -528,6 +528,8 @@ cleanup_pdump_resources(void)
 		if (intf->opts.promisc_mode)
 			rte_eth_promiscuous_disable(intf->port);
 	}
+
+	rte_pdump_uninit();
 }
 
 /* Alarm signal handler, used to check that primary process */
@@ -659,6 +661,14 @@ static void dpdk_init(void)
 	if (rte_eal_init(eal_argc, eal_argv) < 0)
 		rte_exit(EXIT_FAILURE, "EAL init failed: is primary process running?\n");
 
+	/*
+	 * Register pdump callback handler.
+	 * Primary will notify all secondary processes of change.
+	 * No impact for this application, but need to reply.
+	 */
+	if (rte_pdump_init() < 0)
+		rte_exit(EXIT_FAILURE, "EAL pdump init failed\n");
+
 	/*
 	 * If no lcore argument was specified, then run this program as a normal process
 	 * which can be scheduled on any non-isolated CPU.
-- 
2.47.2

[RFC 5/6] pdump: handle pdump requests from primary

[Stephen Hemminger]

The primary process will start to notify all secondary processes
about pdump changes. The pdump secondary process can just call
rte_pdump_init() and it take care of that.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 app/pdump/main.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/app/pdump/main.c b/app/pdump/main.c
index 1741d7e709..626ba0ce93 100644
--- a/app/pdump/main.c
+++ b/app/pdump/main.c
@@ -552,6 +552,7 @@ cleanup_pdump_resources(void)
 		}
 
 	}
+	rte_pdump_uninit();
 	cleanup_rings();
 }
 
@@ -822,6 +823,9 @@ enable_pdump(void)
 	struct pdump_tuples *pt;
 	int ret = 0, ret1 = 0;
 
+	if (rte_pdump_init() < 0)
+		rte_exit(EXIT_FAILURE, "pdump init failed\n");
+
 	for (i = 0; i < num_tuples; i++) {
 		pt = &pdump_t[i];
 		if (pt->dir == RTE_PDUMP_FLAG_RXTX) {
-- 
2.47.2

[RFC 6/6] pdump: forward callback enable to secondary

[Stephen Hemminger]

When packet capture is enabled, need to also notify
secondary processes to force them to do the callbacks.

Requires that all secondary processes also call rte_pdump_init()
or there will be warning about not responding secondary.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 lib/pdump/rte_pdump.c | 213 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 185 insertions(+), 28 deletions(-)

diff --git a/lib/pdump/rte_pdump.c b/lib/pdump/rte_pdump.c
index bfd63fa8c2..b95f7f863d 100644
--- a/lib/pdump/rte_pdump.c
+++ b/lib/pdump/rte_pdump.c
@@ -5,6 +5,7 @@
 #include <stdlib.h>
 
 #include <eal_export.h>
+#include <rte_alarm.h>
 #include <rte_mbuf.h>
 #include <rte_ethdev.h>
 #include <rte_lcore.h>
@@ -26,11 +27,28 @@ RTE_LOG_REGISTER_DEFAULT(pdump_logtype, NOTICE);
 /* Used for the multi-process communication */
 #define PDUMP_MP	"mp_pdump"
 
+/* Overly generous timeout for secondary to respond */
+#define MP_TIMEOUT_S 5
+
 enum pdump_operation {
 	DISABLE = 1,
 	ENABLE = 2
 };
 
+static inline const char *
+pdump_opname(enum pdump_operation op)
+{
+	static char buf[32];
+
+	if (op == DISABLE)
+		return "disable";
+	if (op == ENABLE)
+		return "enable";
+
+	snprintf(buf, sizeof(buf), "op%u", op);
+	return buf;
+}
+
 /* Internal version number in request */
 enum pdump_version {
 	V1 = 1,		    /* no filtering or snap */
@@ -56,6 +74,11 @@ struct pdump_response {
 	int32_t err_value;
 };
 
+struct pdump_bundle {
+	struct rte_mp_msg msg;
+	char peer[];
+};
+
 static struct pdump_rxtx_cbs {
 	struct rte_ring *ring;
 	struct rte_mempool *mp;
@@ -432,34 +455,150 @@ set_pdump_rxtx_cbs(const struct pdump_request *p)
 	return ret;
 }
 
+static void
+pdump_request_to_secondary(const struct pdump_request *req)
+{
+	struct rte_mp_msg mp_req = { };
+	struct rte_mp_reply mp_reply;
+	struct timespec ts = {.tv_sec = MP_TIMEOUT_S, .tv_nsec = 0};
+
+	PDUMP_LOG_LINE(DEBUG, "forward req %s to secondary", pdump_opname(req->op));
+
+	memcpy(mp_req.param, req, sizeof(*req));
+	strlcpy(mp_req.name, PDUMP_MP, sizeof(mp_req.name));
+	mp_req.len_param = sizeof(*req);
+
+	if (rte_mp_request_sync(&mp_req, &mp_reply, &ts) != 0)
+		PDUMP_LOG_LINE(ERR, "rte_mp_request_sync failed");
+
+	else if (mp_reply.nb_sent != mp_reply.nb_received)
+		PDUMP_LOG_LINE(ERR, "not all secondary's replied (sent %u recv %u)",
+			       mp_reply.nb_sent, mp_reply.nb_received);
+
+	free(mp_reply.msgs);
+}
+
+/* Allocate temporary storage for passing state to the alarm thread for deferred handling */
+static struct pdump_bundle *
+pdump_bundle_alloc(const struct rte_mp_msg *mp_msg, const char *peer)
+{
+	struct pdump_bundle *bundle;
+	size_t peer_len = strlen(peer) + 1;
+
+	/* peer is the unix domain socket path */
+	bundle = malloc(sizeof(*bundle) + peer_len);
+	if (bundle == NULL)
+		return NULL;
+
+	bundle->msg = *mp_msg;
+	memcpy(bundle->peer, peer, peer_len);
+	return bundle;
+}
+
+/* Send response to peer */
 static int
-pdump_server(const struct rte_mp_msg *mp_msg, const void *peer)
+pdump_send_response(const struct pdump_request *req, int result, const void *peer)
 {
-	struct rte_mp_msg mp_resp;
-	const struct pdump_request *cli_req;
-	struct pdump_response *resp = (struct pdump_response *)&mp_resp.param;
+	struct rte_mp_msg mp_resp = { };
+	struct pdump_response *resp = (struct pdump_response *)mp_resp.param;
+	int ret;
 
-	/* recv client requests */
-	if (mp_msg->len_param != sizeof(*cli_req)) {
-		PDUMP_LOG_LINE(ERR, "failed to recv from client");
-		resp->err_value = -EINVAL;
-	} else {
-		cli_req = (const struct pdump_request *)mp_msg->param;
-		resp->ver = cli_req->ver;
-		resp->res_op = cli_req->op;
-		resp->err_value = set_pdump_rxtx_cbs(cli_req);
+	if (req) {
+		resp->ver = req->ver;
+		resp->res_op = req->op;
 	}
+	resp->err_value = result;
 
 	rte_strscpy(mp_resp.name, PDUMP_MP, RTE_MP_MAX_NAME_LEN);
 	mp_resp.len_param = sizeof(*resp);
-	mp_resp.num_fds = 0;
-	if (rte_mp_reply(&mp_resp, peer) < 0) {
-		PDUMP_LOG_LINE(ERR, "failed to send to client:%s",
+
+	ret = rte_mp_reply(&mp_resp, peer);
+	if (ret != 0)
+		PDUMP_LOG_LINE(ERR, "failed to send response: %s",
 			  strerror(rte_errno));
-		return -1;
+	return ret;
+}
+
+/* Callback from MP request handler in secondary process */
+static int
+pdump_handle_primary_request(const struct rte_mp_msg *mp_msg, const void *peer)
+{
+	const struct pdump_request *req = NULL;
+	int ret;
+
+	if (mp_msg->len_param != sizeof(*req)) {
+		PDUMP_LOG_LINE(ERR, "invalid request from primary");
+		ret = -EINVAL;
+	} else {
+		req = (const struct pdump_request *)mp_msg->param;
+		PDUMP_LOG_LINE(DEBUG, "secondary pdump %s", pdump_opname(req->op));
+
+		/* Can just do it now, no need for interrupt thread */
+		ret = set_pdump_rxtx_cbs(req);
 	}
 
+	return pdump_send_response(req, ret, peer);
+
+}
+
+/* Callback from the alarm handler (in interrupt thread) which does actual change */
+static void
+__pdump_request(void *param)
+{
+	struct pdump_bundle *bundle = param;
+	struct rte_mp_msg *msg = &bundle->msg;
+	const struct pdump_request *req =
+		(const struct pdump_request *)msg->param;
+	int ret;
+
+	PDUMP_LOG_LINE(DEBUG, "primary pdump %s", pdump_opname(req->op));
+
+	ret = set_pdump_rxtx_cbs(req);
+	ret = pdump_send_response(req, ret, bundle->peer);
+
+	/* Primary process is responsible for broadcasting request to all secondaries */
+	if (ret == 0)
+		pdump_request_to_secondary(req);
+
+	free(bundle);
+}
+
+/* Callback from MP request handler in primary process */
+static int
+pdump_handle_secondary_request(const struct rte_mp_msg *mp_msg, const void *peer)
+{
+	struct pdump_bundle *bundle = NULL;
+	const struct pdump_request *req = NULL;
+	int ret;
+
+	if (mp_msg->len_param != sizeof(*req)) {
+		PDUMP_LOG_LINE(ERR, "invalid request from secondary");
+		ret = -EINVAL;
+		goto error;
+	}
+
+	req = (const struct pdump_request *)mp_msg->param;
+
+	bundle = pdump_bundle_alloc(mp_msg, peer);
+	if (bundle == NULL) {
+		PDUMP_LOG_LINE(ERR, "not enough memory");
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	/*
+	 * We are in IPC callback thread, sync IPC is not possible
+	 * since sending to secondary would cause livelock.
+	 * Delegate the task to interrupt thread.
+	 */
+	ret = rte_eal_alarm_set(1, __pdump_request, bundle);
+	if (ret != 0)
+		goto error;
 	return 0;
+
+error:
+	free(bundle);
+	return pdump_send_response(req, ret, peer);
 }
 
 RTE_EXPORT_SYMBOL(rte_pdump_init)
@@ -469,19 +608,36 @@ rte_pdump_init(void)
 	const struct rte_memzone *mz;
 	int ret;
 
-	mz = rte_memzone_reserve(MZ_RTE_PDUMP_STATS, sizeof(*pdump_stats),
-				 SOCKET_ID_ANY, 0);
-	if (mz == NULL) {
-		PDUMP_LOG_LINE(ERR, "cannot allocate pdump statistics");
-		rte_errno = ENOMEM;
-		return -1;
+	if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
+		ret = rte_mp_action_register(PDUMP_MP, pdump_handle_secondary_request);
+		if (ret && rte_errno != ENOTSUP)
+			return -1;
+
+		mz = rte_memzone_reserve(MZ_RTE_PDUMP_STATS, sizeof(*pdump_stats),
+					 SOCKET_ID_ANY, 0);
+		if (mz == NULL) {
+			PDUMP_LOG_LINE(ERR, "cannot allocate pdump statistics");
+			rte_mp_action_unregister(PDUMP_MP);
+			rte_errno = ENOMEM;
+			return -1;
+		}
+	} else {
+		ret = rte_mp_action_register(PDUMP_MP, pdump_handle_primary_request);
+		if (ret && rte_errno != ENOTSUP)
+			return -1;
+
+		mz = rte_memzone_lookup(MZ_RTE_PDUMP_STATS);
+		if (mz == NULL) {
+			PDUMP_LOG_LINE(ERR, "cannot find pdump statistics");
+			rte_mp_action_unregister(PDUMP_MP);
+			rte_errno = ENOENT;
+			return -1;
+		}
 	}
+
 	pdump_stats = mz->addr;
 	pdump_stats->mz = mz;
 
-	ret = rte_mp_action_register(PDUMP_MP, pdump_server);
-	if (ret && rte_errno != ENOTSUP)
-		return -1;
 	return 0;
 }
 
@@ -491,7 +647,7 @@ rte_pdump_uninit(void)
 {
 	rte_mp_action_unregister(PDUMP_MP);
 
-	if (pdump_stats != NULL) {
+	if (rte_eal_process_type() == RTE_PROC_PRIMARY && pdump_stats != NULL) {
 		rte_memzone_free(pdump_stats->mz);
 		pdump_stats = NULL;
 	}
@@ -580,11 +736,12 @@ pdump_prepare_client_request(const char *device, uint16_t queue,
 	int ret = -1;
 	struct rte_mp_msg mp_req, *mp_rep;
 	struct rte_mp_reply mp_reply;
-	struct timespec ts = {.tv_sec = 5, .tv_nsec = 0};
+	struct timespec ts = {.tv_sec = MP_TIMEOUT_S, .tv_nsec = 0};
 	struct pdump_request *req = (struct pdump_request *)mp_req.param;
 	struct pdump_response *resp;
 
 	if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
+		/* FIXME */
 		PDUMP_LOG_LINE(ERR,
 			  "pdump enable/disable not allowed in primary process");
 		return -EINVAL;
-- 
2.47.2