mtools: fix race issue while mtools invoked frequently

While invoking mtools frequently, the unblocking request
caused race issue. Here is an example of syslinux
[snip]
dd if=/dev/zero of=floppy.img bs=1024 count=144
losetup /dev/loop1 floppy.img
mkdosfs /dev/loop1
syslinux -i /dev/loop1
|plain floppy: device "/proc/6351/fd/3" busy (Resource temporarily unavailable):
|Cannot initialize 'S:'
|Bad target s:/ldlinux.sys
[snip]

The idea is from:
https://bugzilla.redhat.com/show_bug.cgi?id=1235016
https://groups.google.com/a/chromium.org/forum/#!msg/chromium-os-dev/bRPUCFHoBTQ/ZjB8kjjx1vUJ

(From OE-Core rev: 927fad7881841a58e1d88f3a6ce070eaa66ba1a5)

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 45 insertions, 0 deletions

diff --git a/meta/recipes-devtools/mtools/mtools/0001-remove-LOCK_NB-to-use-blocking-request.patch b/meta/recipes-devtools/mtools/mtools/0001-remove-LOCK_NB-to-use-blocking-request.patch
new file mode 100644
index 0000000000..47385a582b
--- /dev/null
+++ b/meta/recipes-devtools/mtools/mtools/0001-remove-LOCK_NB-to-use-blocking-request.patch
@@ -0,0 +1,44 @@
+From 5bdbfe0a63fed48104b17412854b26ee2275869a Mon Sep 17 00:00:00 2001
+From: Hongxu Jia <hongxu.jia@windriver.com>
+Date: Wed, 22 Aug 2018 16:54:39 +0800
+Subject: [PATCH] remove LOCK_NB to use blocking request
+
+While invoking mtools frequently, the unblocking request
+caused race issue. Here is an example of syslinux
+[snip]
+dd if=/dev/zero of=floppy.img bs=1024 count=144
+losetup /dev/loop1 floppy.img
+mkdosfs /dev/loop1
+syslinux -i /dev/loop1
+|plain floppy: device "/proc/6351/fd/3" busy (Resource temporarily unavailable):
+|Cannot initialize 'S:'
+|Bad target s:/ldlinux.sys
+[snip]
+
+The idea is from:
+https://bugzilla.redhat.com/show_bug.cgi?id=1235016
+https://groups.google.com/a/chromium.org/forum/#!msg/chromium-os-dev/bRPUCFHoBTQ/ZjB8kjjx1vUJ
+
+Upstream-Status: Pending
+
+Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
+---
+ lockdev.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/lockdev.h b/lockdev.h
+index 4467bc2..5a135ad 100644
+--- a/lockdev.h
++++ b/lockdev.h
+@@ -43,7 +43,7 @@ int lock_dev(int fd, int mode, struct device *dev)
+                return 0;
+ 
+ #if (defined(HAVE_FLOCK) && defined (LOCK_EX) && defined(LOCK_NB))
+-       if (flock(fd, (mode ? LOCK_EX : LOCK_SH)|LOCK_NB) < 0)
++       if (flock(fd, (mode ? LOCK_EX : LOCK_SH)) < 0)
+ #else /* FLOCK */
+ 
+ #if (defined(HAVE_LOCKF) && defined(F_TLOCK))
+-- 
+2.7.4
+
diff --git a/meta/recipes-devtools/mtools/mtools_4.0.18.bb b/meta/recipes-devtools/mtools/mtools_4.0.18.bb
index dcd32ed94c..91f7b7c610 100644
--- a/meta/recipes-devtools/mtools/mtools_4.0.18.bb
+++ b/meta/recipes-devtools/mtools/mtools_4.0.18.bb
@@ -31,6 +31,7 @@ SRC_URI = "${GNU_MIRROR}/mtools/mtools-${PV}.tar.bz2 \
            file://mtools-makeinfo.patch \
            file://no-x11.gplv3.patch \
            file://0001-Continue-even-if-fs-size-is-not-divisible-by-sectors.patch \
+           file://0001-remove-LOCK_NB-to-use-blocking-request.patch \
            "
 
 SRC_URI_append_class-native = " file://disable-hardcoded-configs.patch"