On Thu, Oct 18, 2012 at 12:23 PM, Stanislav Kinsbursky <skinsbur...@parallels.com> wrote: > This patch is required for checkpoint/restore in userspace. > IOW, c/r requires some way to get all pending IPC messages without deleting > them from the queue (checkpoint can fail and in this case tasks will be > resumed, > so queue have to be valid). > To achive this, new operation flag MSG_COPY for sys_msgrcv() system call was > introduced. If this flag was specified, then mtype is interpreted as number of > the message to copy. > If MSG_COPY is set, then kernel will allocate dummy message with passed size, > and then use new copy_msg() helper function to copy desired message (instead > of > unlinking it from the queue). > > Notes: > 1) Return -ENOSYS if MSG_COPY is specified, but CONFIG_CHECKPOINT_RESTORE is > not set.
Stanislav, A naive question, because I have not followed C/R closely. How do you deal with the case that other processes may be reading from the queue? (Or is that disabled during checkpointing?) Thanks, Michael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
