[lvm-devel] [PATCH] Add check for semaphore kernel support
Peter Rajnoha
prajnoha at redhat.com
Mon Aug 2 19:24:57 UTC 2010
We also need to check for kernel semaphore support (part of System V IPC,
kernel's CONFIG_SYSVIPC). If not compiled in the kernel, we need to disable
udev synchronisation code and show a warning message at least (so one knows
that it should be added in the kernel or that libdebmapper should be compiled
without udev_sync alternatively).
Inspired by util-linux-ng's ipcs code.
Initiated by the problem reported here:
http://bugs.gentoo.org/show_bug.cgi?id=330375
Peter
---
libdm/libdm-common.c | 33 +++++++++++++++++++++++++++++----
1 files changed, 29 insertions(+), 4 deletions(-)
diff --git a/libdm/libdm-common.c b/libdm/libdm-common.c
index 438e461..23dd761 100644
--- a/libdm/libdm-common.c
+++ b/libdm/libdm-common.c
@@ -60,6 +60,7 @@ static char _dm_dir[PATH_MAX] = DEV_DIR DM_DIR;
static int _verbose = 0;
#ifdef UDEV_SYNC_SUPPORT
+static int _semaphore_supported = -1;
static int _udev_running = -1;
static int _sync_with_udev = 1;
static int _udev_checking = 1;
@@ -929,6 +930,23 @@ int dm_udev_wait(uint32_t cookie)
#else /* UDEV_SYNC_SUPPORT */
+static int _check_semaphore_is_supported()
+{
+ int maxid;
+ union semun arg;
+ struct seminfo seminfo;
+
+ arg.array = (unsigned short int *) (void *) &seminfo;
+ maxid = semctl(0, 0, SEM_INFO, arg);
+
+ if (maxid < 0) {
+ log_warn("Kernel not configured for semaphores (System V IPC). "
+ "Not using udev synchronisation code.");
+ return 0;
+ }
+
+ return 1;
+}
static int _check_udev_is_running(void)
{
@@ -958,20 +976,27 @@ bad:
return 0;
}
-void dm_udev_set_sync_support(int sync_with_udev)
+static void _check_udev_sync_requirements_once()
{
+ if (_semaphore_supported < 0)
+ _semaphore_supported = _check_semaphore_is_supported();
+
if (_udev_running < 0)
_udev_running = _check_udev_is_running();
+}
+void dm_udev_set_sync_support(int sync_with_udev)
+{
+ _check_udev_sync_requirements_once();
_sync_with_udev = sync_with_udev;
}
int dm_udev_get_sync_support(void)
{
- if (_udev_running < 0)
- _udev_running = _check_udev_is_running();
+ _check_udev_sync_requirements_once();
- return dm_cookie_supported() && _udev_running && _sync_with_udev;
+ return _semaphore_supported && dm_cookie_supported() &&
+ _udev_running && _sync_with_udev;
}
void dm_udev_set_checking(int checking)
More information about the lvm-devel
mailing list