From d33d0b01bf102630b7e25fb4cab9ac3d9f3152fe Mon Sep 17 00:00:00 2001 From: Peter Rajnoha Date: Tue, 3 Aug 2010 07:56:03 +0000 Subject: [PATCH] Add check for kernel semaphore support and disable udev_sync if not available. udev_sync feature requires semaphores (part of System V IPC) to be configured in kernel (CONFIG_SYSVIPC). Check whether it is supported and if not, give a warning message and disable udev synchronisation code automatically to avoid any further error states and associated problems. One should use the kernel with System V IPC support enabled or libdevmapper with udev_sync feature disabled. --- WHATS_NEW_DM | 1 + libdm/libdm-common.c | 33 +++++++++++++++++++++++++++++---- 2 files changed, 30 insertions(+), 4 deletions(-) diff --git a/WHATS_NEW_DM b/WHATS_NEW_DM index 18a522995..8c4a064f9 100644 --- a/WHATS_NEW_DM +++ b/WHATS_NEW_DM @@ -1,5 +1,6 @@ Version 1.02.54 - ================================ + Add check for kernel semaphore support and disable udev_sync if not available. Version 1.02.53 - 28th July 2010 ================================ diff --git a/libdm/libdm-common.c b/libdm/libdm-common.c index 438e46140..33a35cbd5 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.__buf = &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) -- 2.43.5