From: David Goulet <dgoulet@efficios.com>
Date: Thu, 16 Aug 2012 20:12:12 +0000 (-0400)
Subject: Deny register consumer if one exists
X-Git-Tag: v2.1.0-rc1~8
X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=commitdiff_plain;h=8d3113b21fe5ed84af58fbfdff9ad7742db507d5

Deny register consumer if one exists

Is a LTTNG_REGISTER_CONSUMER command is received and a consumer is
already spawned, the command is denied returning a kernel consumer
error.

CC: Julien Desfossez <julien.desfossez@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index f24b317d0..d0b1e17e5 100644
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -4328,6 +4328,16 @@ static int process_client_msg(struct command_ctx *cmd_ctx, int sock,
 		goto error;
 	}
 
+	/* Deny register consumer if we already have a spawned consumer. */
+	if (cmd_ctx->lsm->cmd_type == LTTNG_REGISTER_CONSUMER) {
+		pthread_mutex_lock(&kconsumer_data.pid_mutex);
+		if (kconsumer_data.pid > 0) {
+			ret = LTTCOMM_KERN_CONSUMER_FAIL;
+			goto error;
+		}
+		pthread_mutex_unlock(&kconsumer_data.pid_mutex);
+	}
+
 	/*
 	 * Check for command that don't needs to allocate a returned payload. We do
 	 * this here so we don't have to make the call for no payload at each