[dpdk-stable] patch 'doc: add a note for multi-process in mempool guide' has been queued to LTS release 18.11.3

[Kevin Traynor]

Hi,

FYI, your patch has been queued to LTS release 18.11.3

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 08/28/19. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable-queue

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable-queue/commit/44eddd06f4c240f27722e2d31c8d51f488088b1c

Thanks.

Kevin Traynor

---
>From 44eddd06f4c240f27722e2d31c8d51f488088b1c Mon Sep 17 00:00:00 2001
From: Gage Eads <gage.eads at intel.com>
Date: Thu, 20 Jun 2019 17:07:35 -0500
Subject: [PATCH] doc: add a note for multi-process in mempool guide

[ upstream commit 4ae9f32eccef0e12ec7282889fc2a2e444b8ec4d ]

The mempool library assigns handler ops indexes based on the dynamic load
order of mempool handlers. Indexes are used so a mempool can be used by
multiple processes, but this only works if all processes agree on the
mapping from index to mempool handler.

When using the '-d' argument, it's possible for different processes to load
mempool handlers in different orders, and thus have different
index->handler mappings. Using a mempool in multiple of such processes will
result in undefined behavior.

This commit adds a note to the mempool library programmer's guide warning
users against this.

Fixes: 449c49b93a6b ("mempool: support handler operations")

Signed-off-by: Gage Eads <gage.eads at intel.com>
Acked-by: Andrew Rybchenko <arybchenko at solarflare.com>
---
 doc/guides/prog_guide/mempool_lib.rst | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/doc/guides/prog_guide/mempool_lib.rst b/doc/guides/prog_guide/mempool_lib.rst
index 52a569f57..3bb84b0a6 100644
--- a/doc/guides/prog_guide/mempool_lib.rst
+++ b/doc/guides/prog_guide/mempool_lib.rst
@@ -134,4 +134,12 @@ For applications that use ``rte_pktmbuf_create()``, there is a config setting
 an alternative mempool handler.
 
+  .. note::
+
+    When running a DPDK application with shared libraries, mempool handler
+    shared objects specified with the '-d' EAL command-line parameter are
+    dynamically loaded. When running a multi-process application with shared
+    libraries, the -d arguments for mempool handlers *must be specified in the
+    same order for all processes* to ensure correct operation.
+
 
 Use Cases
-- 
2.20.1

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2019-08-22 19:38:23.168129454 +0100
+++ 0042-doc-add-a-note-for-multi-process-in-mempool-guide.patch	2019-08-22 19:38:20.474025998 +0100
@@ -1 +1 @@
-From 4ae9f32eccef0e12ec7282889fc2a2e444b8ec4d Mon Sep 17 00:00:00 2001
+From 44eddd06f4c240f27722e2d31c8d51f488088b1c Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 4ae9f32eccef0e12ec7282889fc2a2e444b8ec4d ]
+
@@ -20 +21,0 @@
-Cc: stable at dpdk.org