[OE-core] [PATCH 29/43] linux-yocto-rt/4.19: fix merge conflict in lru_drain

[Armin Kuster]

From: Bruce Ashfield <bruce.ashfield at gmail.com>

Paul Gortmaker sent along the following fixup for 4.19-rt:

[
  Author: Paul Gortmaker <paul.gortmaker at windriver.com>
  Date:   Mon Apr 15 12:01:31 2019 -0400

    Revert "mm: handle lru_add_drain_all for UP properly"

    This reverts commit e6e9d6e290028b0a6b83b563fad9fafa7f1d515e.

    It was a 4.19.31 backport of commit 6ea183d60c46 ("mm: handle
    lru_add_drain_all for UP properly").  In summary, what that did
    was to fix a possible harmless WARN_ON on non-SMP, introduced at
    commit 4d43d395fed1 ("workqueue: Try to catch flush_work() without
    INIT_WORK().") by adding non-SMP variants of lru functions.

    The combination of that, with the -rt commit 473f14a9f234 ("mm:
    perform lru_add_drain_all() remotely") at the merge of the two
    results in the following build failure:

      mm/swap.c:736:2: error: #endif without #if

    since the -rt change wants RT specific lru and the stable backport
    wants non-SMP specific lru, and a chunk of the backport with
    an #ifdef CONFIG_SMP is missing.

    However, before we add a four way cluster of ifdeffery to handle all
    cases, we note 4d43d395fed1 was added to the v5.1 release, and it
    was not (currently) backported to any 4.19.x stable release - so it is
    unclear to me why this commit was ever backported to 4.19.31 at all.

    Further, we note this change was to mm/swap.c -- and by definition,
    any preempt-rt deployment that uses swap for anything other than a
    failure contingency mitigation is broken by design.

    Given all that, I decided that the best path forward was to revert
    the two of the three chunks of the backport that remain in the -rt
    branch, and return us to the pre-4.19.31 merge behaviour for -rt.

    Signed-off-by: Paul Gortmaker <paul.gortmaker at windriver.com>
]

Signed-off-by: Paul Gortmaker <paul.gortmaker at windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield at gmail.com>
Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808 at gmail.com>
---
 meta/recipes-kernel/linux/linux-yocto-rt_4.19.bb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/meta/recipes-kernel/linux/linux-yocto-rt_4.19.bb b/meta/recipes-kernel/linux/linux-yocto-rt_4.19.bb
index cdba9d2..834b8fc 100644
--- a/meta/recipes-kernel/linux/linux-yocto-rt_4.19.bb
+++ b/meta/recipes-kernel/linux/linux-yocto-rt_4.19.bb
@@ -11,7 +11,7 @@ python () {
         raise bb.parse.SkipRecipe("Set PREFERRED_PROVIDER_virtual/kernel to linux-yocto-rt to enable it")
 }
 
-SRCREV_machine ?= "b0ea9ef736c8ab8695bdfba61cd121ce5aa47e49"
+SRCREV_machine ?= "c279a81f1e654023c4cc78afa9f14350ee5f836f"
 SRCREV_meta ?= "9bda6190bfc9e7858c2f7588109a0ec966f37a09"
 
 SRC_URI = "git://git.yoctoproject.org/linux-yocto.git;branch=${KBRANCH};name=machine \
-- 
2.7.4