[dpdk-dev] [PATCH] fbarray: get fbarrays from containerized secondary

[ogawa.yasufumi at lab.ntt.co.jp]

From: Yasufumi Ogawa <ogawa.yasufumi at lab.ntt.co.jp>

In secondary_msl_create_walk(), it creates a file for fbarrays with its
PID for reserving unique name among secondary processes. However, it
does not work as expected if secondary is run as app container becuase
each of containerized secondary has PID 1. To reserve unique name, use
hostname instead of PID if the value is 1.

Cc: stable at dpdk.org

Signed-off-by: Yasufumi Ogawa <ogawa.yasufumi at lab.ntt.co.jp>
---
 lib/librte_eal/linux/eal/eal_memalloc.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/lib/librte_eal/linux/eal/eal_memalloc.c b/lib/librte_eal/linux/eal/eal_memalloc.c
index 1e9ebb86d..beec03648 100644
--- a/lib/librte_eal/linux/eal/eal_memalloc.c
+++ b/lib/librte_eal/linux/eal/eal_memalloc.c
@@ -1362,6 +1362,7 @@ secondary_msl_create_walk(const struct rte_memseg_list *msl,
 	struct rte_memseg_list *primary_msl, *local_msl;
 	char name[PATH_MAX];
 	int msl_idx, ret;
+	char proc_id[16];
 
 	if (msl->external)
 		return 0;
@@ -1371,8 +1372,28 @@ secondary_msl_create_walk(const struct rte_memseg_list *msl,
 	local_msl = &local_memsegs[msl_idx];
 
 	/* create distinct fbarrays for each secondary */
-	snprintf(name, RTE_FBARRAY_NAME_LEN, "%s_%i",
-		primary_msl->memseg_arr.name, getpid());
+	/* if run secondary in a container, the name of fbarray file cannot
+	 * be decided with pid because getpid() always returns 1, so use
+	 * hostname as a unique identifier among containers instead.
+	 */
+	if (getpid() == 1) {
+		FILE *hn_fp;
+		hn_fp = fopen("/etc/hostname", "r");
+		if (hn_fp == NULL) {
+			RTE_LOG(ERR, EAL,
+				"Cannot open '/etc/hostname' for secondary\n");
+			return -1;
+		}
+
+		/* with docker, /etc/hostname just has one entry of hostname */
+		if (fscanf(hn_fp, "%s", proc_id) == EOF)
+			return -1;
+		fclose(hn_fp);
+	} else
+		sprintf(proc_id, "%d", (int)getpid());
+
+	snprintf(name, RTE_FBARRAY_NAME_LEN, "%s_%s",
+			primary_msl->memseg_arr.name, proc_id);
 
 	ret = rte_fbarray_init(&local_msl->memseg_arr, name,
 		primary_msl->memseg_arr.len,
-- 
2.17.1