[dpdk-stable] patch 'mem: fix alignment of requested virtual areas' has been queued to stable release 18.05.1

[Christian Ehrhardt]

Hi,

FYI, your patch has been queued to stable release 18.05.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 08/01/18. So please
shout if anyone has objections.

Thanks.

Christian Ehrhardt <christian.ehrhardt at canonical.com>

---
>From a132f9990766c2fdb0a6895614bd37f91038d966 Mon Sep 17 00:00:00 2001
From: Anatoly Burakov <anatoly.burakov at intel.com>
Date: Mon, 16 Jul 2018 15:57:19 +0100
Subject: [PATCH] mem: fix alignment of requested virtual areas

[ upstream commit d5dd22c9f6ba86ce9175d84a8f95946edbdb04fc ]

The original code did not align any addresses that were requested as
page-aligned, but were different because addr_is_hint was set.

Below fix by Dariusz has introduced an issue where all unaligned addresses
were left as unaligned.

This patch is a partial revert of
commit 7fa7216ed48d ("mem: fix alignment of requested virtual areas")

and implements a proper fix for this issue, by asking for alignment in all
but the following two cases:

1) page size is equal to system page size, or
2) we got an aligned requested address, and will not accept a different one

This ensures that alignment is performed in all cases, except for those we
can guarantee that the address will not need alignment.

Fixes: b7cc54187ea4 ("mem: move virtual area function in common directory")
Fixes: 7fa7216ed48d ("mem: fix alignment of requested virtual areas")

Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
Tested-by: Lei Yao <lei.a.yao at intel.com>
Acked-by: Dariusz Stojaczyk <dariuszx.stojaczyk at intel.com>
---
 lib/librte_eal/common/eal_common_memory.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/lib/librte_eal/common/eal_common_memory.c b/lib/librte_eal/common/eal_common_memory.c
index ecc5bb248..341c28ad7 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -63,14 +63,17 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
 		addr_is_hint = true;
 	}
 
-	/* if requested address is not aligned by page size, or if requested
-	 * address is NULL, add page size to requested length as we may get an
-	 * address that's aligned by system page size, which can be smaller than
-	 * our requested page size. additionally, we shouldn't try to align if
-	 * system page size is the same as requested page size.
+	/* we don't need alignment of resulting pointer in the following cases:
+	 *
+	 * 1. page size is equal to system size
+	 * 2. we have a requested address, and it is page-aligned, and we will
+	 *    be discarding the address if we get a different one.
+	 *
+	 * for all other cases, alignment is potentially necessary.
 	 */
 	no_align = (requested_addr != NULL &&
-		((uintptr_t)requested_addr & (page_sz - 1)) == 0) ||
+		requested_addr == RTE_PTR_ALIGN(requested_addr, page_sz) &&
+		!addr_is_hint) ||
 		page_sz == system_page_sz;
 
 	do {
-- 
2.17.1