[PATCH 08/39] staging/lustre/libcfs: improve validity test for valid file descriptors

[Peng Tao <bergwolf@gmail.com>]

From: Bob Glossman <bob.glossman@intel.com>

File descriptor members of struct lustre_kernelcomm aren't set to
anything special at start time.
This leads to incorrect tests and skipping valid fd closes at stop time.
Fixed by defining, setting, and testing against a specific LK_NOFD value.

Lustre-change: http://review.whamcloud.com/7275
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3683
Signed-off-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Keith Mannthey <keith.mannthey@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
---
 .../include/linux/libcfs/libcfs_kernelcomm.h       |    1 +
 .../lustre/lustre/libcfs/kernel_user_comm.c        |   10 ++++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/lustre/include/linux/libcfs/libcfs_kernelcomm.h b/drivers/staging/lustre/include/linux/libcfs/libcfs_kernelcomm.h
index 596a15f..4e12ffc 100644
--- a/drivers/staging/lustre/include/linux/libcfs/libcfs_kernelcomm.h
+++ b/drivers/staging/lustre/include/linux/libcfs/libcfs_kernelcomm.h
@@ -97,6 +97,7 @@ extern int libcfs_kkuc_group_foreach(int group, libcfs_kkuc_cb_t cb_func,
 				     void *cb_arg);
 
 #define LK_FLG_STOP 0x01
+#define LK_NOFD -1U
 
 /* kernelcomm control structure, passed from userspace to kernel */
 typedef struct lustre_kernelcomm {
diff --git a/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c b/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c
index 74a0db5..9e5e3cc 100644
--- a/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c
+++ b/drivers/staging/lustre/lustre/libcfs/kernel_user_comm.c
@@ -56,6 +56,8 @@ int libcfs_ukuc_start(lustre_kernelcomm *link, int group)
 {
 	int pfd[2];
 
+	link->lk_rfd = link->lk_wfd = LK_NOFD;
+
 	if (pipe(pfd) < 0)
 		return -errno;
 
@@ -69,9 +71,13 @@ int libcfs_ukuc_start(lustre_kernelcomm *link, int group)
 
 int libcfs_ukuc_stop(lustre_kernelcomm *link)
 {
-	if (link->lk_wfd > 0)
+	int rc;
+
+	if (link->lk_wfd != LK_NOFD)
 		close(link->lk_wfd);
-	return close(link->lk_rfd);
+	rc = close(link->lk_rfd);
+	link->lk_rfd = link->lk_wfd = LK_NOFD;
+	return rc;
 }
 
 #define lhsz sizeof(*kuch)
-- 
1.7.9.5