Hello

I find an issue when use  dmsetup in the situation udev event timeout.

Dmsetup use the dm_udev_wait function sync with udev event.When use the dmsetup generate a new dm-disk, if the raw disk is abnormal(for example ,a ipsan disk hung IO request), the udevd daemon handle the dm-disk udev event maybe timeout, and will not notify the dmsetup  by semaphore. And because the  dm_udev_wait use the semop to sync with udevd, if udevd event timeout, the dmsetup will hung forever even when the raw disk be recovery.

I wonder if we could use the semtimedop instead semop to add the timeout in function  dm_udev_wait. If the udevd daemon timeout when handle the dm event, the dm_udev_wait could timeout too, and the dmsetup could return error.

This is my patch base lvm2-2.02.115-3: