From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Benjamin Marzinski <bmarzins@redhat.com>

Date: Sat, 21 Mar 2020 23:49:59 -0500

Subject: [PATCH] libmutipath: don't close fd on dm_lib_release

If dm_hold_control_open() isn't set, when dm_lib_release() is called, it

will close the control fd. The control fd will get re-opened on the next

dm_task_run() call, but if there is a dm_task_run() call already

in progress in another thread, it can fail. Since many of the

device-mapper callouts happen with the vecs lock held, this wasn't too

noticeable, but there is code that calls dm_task_run() without the

vecs lock held, notably the dmevent waiter code.

Since, as Martin pointed out, dm_hold_control_open() hasn't always

existed in libdevmapper, check if it's supported on compilation,

and update the version requirements if so.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>

---

 libmultipath/Makefile    | 4 ++++

 libmultipath/devmapper.c | 7 ++++++-

 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/libmultipath/Makefile b/libmultipath/Makefile

index e5651e49..ad690a49 100644

--- a/libmultipath/Makefile

+++ b/libmultipath/Makefile

@@ -36,6 +36,10 @@ ifneq ($(call check_func,dm_task_deferred_remove,/usr/include/libdevmapper.h),0)

 	CFLAGS += -DLIBDM_API_DEFERRED

 endif

+ifneq ($(call check_func,dm_hold_control_dev,/usr/include/libdevmapper.h),0)

+	CFLAGS += -DLIBDM_API_HOLD_CONTROL

+endif

+

 OBJS = memory.o parser.o vector.o devmapper.o callout.o \

 	hwtable.o blacklist.o util.o dmparser.o config.o \

 	structs.o discovery.o propsel.o dict.o \

diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c

index bed8ddc6..13a1cf53 100644

--- a/libmultipath/devmapper.c

+++ b/libmultipath/devmapper.c

@@ -108,7 +108,9 @@ dm_lib_prereq (void)

 {

 	char version[64];

 	int v[3];

-#if defined(LIBDM_API_DEFERRED)

+#if defined(LIBDM_API_HOLD_CONTROL)

+	int minv[3] = {1, 2, 111};

+#elif defined(LIBDM_API_DEFERRED)

 	int minv[3] = {1, 2, 89};

 #elif defined(DM_SUBSYSTEM_UDEV_FLAG0)

 	int minv[3] = {1, 2, 82};

@@ -254,6 +256,9 @@ void libmp_dm_init(void)

 	memcpy(conf->version, version, sizeof(version));

 	put_multipath_config(conf);

 	dm_init(verbosity);

+#ifdef LIBDM_API_HOLD_CONTROL

+	dm_hold_control_dev(1);

+#endif

 	dm_udev_set_sync_support(libmp_dm_udev_sync);

 }

-- 

2.17.2