# DF-5513 VERDICT

# ppb_request_bus() owner self-request sleeps uninterruptibly forever

REPRODUCED (rig) 4/4 fresh-boot runs (deterministic test)
==========================================

A kernel thread re-requests the bus for the device that already owns it
with PPB_WAIT|PPB_NOINTR (what pcfclock_open() passes, since
PPB_NOINTR==0): the thread is still in tsleep("ppbreq") after 3 s in
every run, and only a ppb_release_bus() from another thread revives it.
In production nobody releases on the sleeper's behalf: the owner waits
for itself forever, unkillable (no PCATCH), same D-state wedge DF-5029
demonstrated end-to-end on real hardware from userland via the
world-readable /dev/pcfclock0.  This finding pins the ppbus-side defect
and the bus-level fix (idempotency), which also protects any future
driver that forgets a HAVEBUS-style guard.

FIX VALIDATED: with the owner==dev early-out the re-request returns 0
immediately (no sleep) on both patched boots.

--
status=reproduced reproduced=True impact=none confidence=certain
fix_status=fixed (baseline reproduced, patched behavior gone)

## Fix status (batch validation)
Applied with the 36 sibling fix.diffs of this batch in findings/poc/_batch41/all_fixes.patch; single in-guest `make -j6 nativekernel KERNCONF=X86_64_GENERIC` completed RC=0 with zero errors under -Werror (full log: findings/poc/_batch41/fix_build8.log). Behavior A/B intentionally skipped for this Info-tier item.