[dpdk-dev] [PATCH 20.08] telemetry: add upper limit on connections

[dpdk-dev] [PATCH 20.08] telemetry: add upper limit on connections

[Ciara Power]

This patch limits the number of client connections to the new telemetry
socket. The limit is set at 10.

Signed-off-by: Ciara Power <ciara.power@intel.com>
---
 lib/librte_telemetry/telemetry.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/librte_telemetry/telemetry.c b/lib/librte_telemetry/telemetry.c
index 56a2fed3f5..5c9d7983e3 100644
--- a/lib/librte_telemetry/telemetry.c
+++ b/lib/librte_telemetry/telemetry.c
@@ -7,6 +7,7 @@
 #include <sys/socket.h>
 #include <sys/un.h>
 #include <dlfcn.h>
+#include <semaphore.h>
 
 /* we won't link against libbsd, so just always use DPDKs-specific strlcpy */
 #undef RTE_USE_LIBBSD
@@ -23,6 +24,7 @@
 #define MAX_CMD_LEN 56
 #define MAX_HELP_LEN 64
 #define MAX_OUTPUT_LEN (1024 * 16)
+#define MAX_CONNECTIONS 10
 
 static void *
 client_handler(void *socket);
@@ -37,6 +39,7 @@ struct socket {
 	int sock;
 	char path[sizeof(((struct sockaddr_un *)0)->sun_path)];
 	handler fn;
+	sem_t *limit;
 };
 static struct socket v2_socket; /* socket for v2 telemetry */
 static struct socket v1_socket; /* socket for v1 telemetry */
@@ -46,6 +49,7 @@ static struct cmd_callback callbacks[TELEMETRY_MAX_CALLBACKS];
 static int num_callbacks; /* How many commands are registered */
 /* Used when accessing or modifying list of command callbacks */
 static rte_spinlock_t callback_sl = RTE_SPINLOCK_INITIALIZER;
+static sem_t v2_limit;
 
 int
 rte_telemetry_register_cmd(const char *cmd, telemetry_cb fn, const char *help)
@@ -263,6 +267,7 @@ client_handler(void *sock_id)
 		bytes = read(s, buffer, sizeof(buffer) - 1);
 	}
 	close(s);
+	sem_post(&v2_limit);
 	return NULL;
 }
 
@@ -272,6 +277,8 @@ socket_listener(void *socket)
 	while (1) {
 		pthread_t th;
 		struct socket *s = (struct socket *)socket;
+		if (s->limit != NULL)
+			sem_wait(s->limit);
 		int s_accepted = accept(s->sock, NULL, NULL);
 		if (s_accepted < 0) {
 			snprintf(telemetry_log_error,
@@ -372,6 +379,9 @@ telemetry_v2_init(const char *runtime_dir)
 {
 	pthread_t t_new;
 
+	RTE_BUILD_BUG_ON(_SC_SEM_VALUE_MAX < MAX_CONNECTIONS);
+	(void)sem_init(&v2_limit, 0, MAX_CONNECTIONS);
+	v2_socket.limit = &v2_limit;
 	rte_telemetry_register_cmd("/", list_commands,
 			"Returns list of available commands, Takes no parameters");
 	rte_telemetry_register_cmd("/info", json_info,
-- 
2.17.1

Re: [dpdk-dev] [PATCH 20.08] telemetry: add upper limit on connections

[Stephen Hemminger]

On Mon, 18 May 2020 17:12:32 +0100
Ciara Power <ciara.power@intel.com> wrote:

> This patch limits the number of client connections to the new telemetry
> socket. The limit is set at 10.
> 
> Signed-off-by: Ciara Power <ciara.power@intel.com>

The upper limit is fine, but using System V semaphores is not a good
way to do this. Please consider using some other atomic primitive.

Re: [dpdk-dev] [PATCH 20.08] telemetry: add upper limit on connections

[Thomas Monjalon]

19/05/2020 02:07, Stephen Hemminger:
> On Mon, 18 May 2020 17:12:32 +0100
> Ciara Power <ciara.power@intel.com> wrote:
> 
> > This patch limits the number of client connections to the new telemetry
> > socket. The limit is set at 10.
> > 
> > Signed-off-by: Ciara Power <ciara.power@intel.com>
> 
> The upper limit is fine, but using System V semaphores is not a good
> way to do this. Please consider using some other atomic primitive.

Why no reply?

Re: [dpdk-dev] [PATCH 20.08] telemetry: add upper limit on connections

[Power, Ciara]

>-----Original Message-----
>From: Thomas Monjalon <thomas@monjalon.net>
>Sent: Friday 10 July 2020 21:51
>To: Power, Ciara <ciara.power@intel.com>
>Cc: dev@dpdk.org; Laatz, Kevin <kevin.laatz@intel.com>; Stephen
>Hemminger <stephen@networkplumber.org>; Richardson, Bruce
><bruce.richardson@intel.com>
>Subject: Re: [dpdk-dev] [PATCH 20.08] telemetry: add upper limit on
>connections
>
>19/05/2020 02:07, Stephen Hemminger:
>> On Mon, 18 May 2020 17:12:32 +0100
>> Ciara Power <ciara.power@intel.com> wrote:
>>
>> > This patch limits the number of client connections to the new
>> > telemetry socket. The limit is set at 10.
>> >
>> > Signed-off-by: Ciara Power <ciara.power@intel.com>
>>
>> The upper limit is fine, but using System V semaphores is not a good
>> way to do this. Please consider using some other atomic primitive.
>
>Why no reply?
>

Hi Thomas,

I had contacted Stephen offline for some detail on his suggestion. I thought I would have a patch sent soon after, but it took longer than expected, and I forgot to reply on list.
I have a patch in progress that will hopefully be sent up soon after internal review.

Thanks,
Ciara

[dpdk-dev] [PATCH v2] telemetry: add upper limit on connections

[Ciara Power]

This patch limits the number of client connections to the new telemetry
socket. The limit is set to 10.

Signed-off-by: Ciara Power <ciara.power@intel.com>
---
 lib/librte_telemetry/telemetry.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/lib/librte_telemetry/telemetry.c b/lib/librte_telemetry/telemetry.c
index e7e3d861d..025228273 100644
--- a/lib/librte_telemetry/telemetry.c
+++ b/lib/librte_telemetry/telemetry.c
@@ -23,6 +23,7 @@
 #define MAX_CMD_LEN 56
 #define MAX_HELP_LEN 64
 #define MAX_OUTPUT_LEN (1024 * 16)
+#define MAX_CONNECTIONS 10
 
 static void *
 client_handler(void *socket);
@@ -37,6 +38,7 @@ struct socket {
 	int sock;
 	char path[sizeof(((struct sockaddr_un *)0)->sun_path)];
 	handler fn;
+	uint16_t *num_clients;
 };
 static struct socket v2_socket; /* socket for v2 telemetry */
 static struct socket v1_socket; /* socket for v1 telemetry */
@@ -46,6 +48,7 @@ static struct cmd_callback callbacks[TELEMETRY_MAX_CALLBACKS];
 static int num_callbacks; /* How many commands are registered */
 /* Used when accessing or modifying list of command callbacks */
 static rte_spinlock_t callback_sl = RTE_SPINLOCK_INITIALIZER;
+static uint16_t v2_clients;
 
 int
 rte_telemetry_register_cmd(const char *cmd, telemetry_cb fn, const char *help)
@@ -263,6 +266,7 @@ client_handler(void *sock_id)
 		bytes = read(s, buffer, sizeof(buffer) - 1);
 	}
 	close(s);
+	__atomic_sub_fetch(&v2_clients, 1, __ATOMIC_RELAXED);
 	return NULL;
 }
 
@@ -279,6 +283,16 @@ socket_listener(void *socket)
 				"Error with accept, telemetry thread quitting");
 			return NULL;
 		}
+		if (s->num_clients != NULL) {
+			uint16_t conns = __atomic_load_n(s->num_clients,
+					__ATOMIC_RELAXED);
+			if (conns >= MAX_CONNECTIONS) {
+				close(s_accepted);
+				continue;
+			}
+			__atomic_add_fetch(s->num_clients, 1,
+					__ATOMIC_RELAXED);
+		}
 		pthread_create(&th, NULL, s->fn, (void *)(uintptr_t)s_accepted);
 		pthread_detach(th);
 	}
@@ -373,6 +387,7 @@ telemetry_v2_init(const char *runtime_dir, rte_cpuset_t *cpuset)
 {
 	pthread_t t_new;
 
+	v2_socket.num_clients = &v2_clients;
 	rte_telemetry_register_cmd("/", list_commands,
 			"Returns list of available commands, Takes no parameters");
 	rte_telemetry_register_cmd("/info", json_info,
-- 
2.17.1

Re: [dpdk-dev] [PATCH v2] telemetry: add upper limit on connections

[Thomas Monjalon]

15/07/2020 17:03, Ciara Power:
> This patch limits the number of client connections to the new telemetry
> socket. The limit is set to 10.
> 
> Signed-off-by: Ciara Power <ciara.power@intel.com>

Not sure I should wait for any review.
Applied, thanks