Re: Task watchers v2

plain text document attachment (task-watchers-v2) Associate function calls with significant events in a task's lifetime much like we handle kernel and module init/exit functions. This creates a table for each of the following events in the task_watchers_table ELF section: WATCH_TASK_INIT at the beginning of a fork/clone system call when the new task struct first becomes available. WATCH_TASK_CLONE just before returning successfully from a fork/clone. WATCH_TASK_EXEC just before successfully returning from the exec system call. WATCH_TASK_UID every time a task's real or effective user id changes. WATCH_TASK_GID every time a task's real or effective group id changes. WATCH_TASK_EXIT at the beginning of do_exit when a task is exiting for any reason. WATCH_TASK_FREE is called before critical task structures like the mm_struct become inaccessible and the task is subsequently freed. The next patch will add a debugfs interface for measuring fork and exit rates which can be used to calculate the overhead of the task watcher infrastructure. Subsequent patches will make use of task watchers to simplify fork, exit, and many of the system calls that set [er][ug]ids.