pub(crate) static SCHED_IDENTITY: RwLock<SchedIdentity>Expand description
Identity maps : cold path: PID/TID lookups, process groups, sessions, parent/child.
Separate from GLOBAL_SCHED_STATE so that identity lookups (getpid, getpgid,
setpgid, etc.) never contend with fork/exit/zombie management.
Upgraded to an RwLock so that concurrent readers (getpid, gettid,
getppid, getpgid, getsid, get_task_by_pid) do not serialize on
each other. Only writers (fork, exit, setpgid, setsid, kill)
acquire the exclusive write lock.
Lock order: SCHED_IDENTITY before LOCAL (never the reverse). SCHED_IDENTITY and BLOCKED_TASKS are independent : never hold both.