diff options
Diffstat (limited to 'sys/kern/kern_umtx.c')
-rw-r--r-- | sys/kern/kern_umtx.c | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/sys/kern/kern_umtx.c b/sys/kern/kern_umtx.c index 5b42c6fd118a..317e05bfb57a 100644 --- a/sys/kern/kern_umtx.c +++ b/sys/kern/kern_umtx.c @@ -1302,6 +1302,47 @@ umtx_pi_adjust_thread(struct umtx_pi *pi, struct thread *td) return (1); } +static struct umtx_pi * +umtx_pi_next(struct umtx_pi *pi) +{ + struct umtx_q *uq_owner; + + if (pi->pi_owner == NULL) + return (NULL); + uq_owner = pi->pi_owner->td_umtxq; + if (uq_owner == NULL) + return (NULL); + return (uq_owner->uq_pi_blocked); +} + +/* + * Floyd's Cycle-Finding Algorithm. + */ +static bool +umtx_pi_check_loop(struct umtx_pi *pi) +{ + struct umtx_pi *pi1; /* fast iterator */ + + mtx_assert(&umtx_lock, MA_OWNED); + if (pi == NULL) + return (false); + pi1 = pi; + for (;;) { + pi = umtx_pi_next(pi); + if (pi == NULL) + break; + pi1 = umtx_pi_next(pi1); + if (pi1 == NULL) + break; + pi1 = umtx_pi_next(pi1); + if (pi1 == NULL) + break; + if (pi == pi1) + return (true); + } + return (false); +} + /* * Propagate priority when a thread is blocked on POSIX * PI mutex. @@ -1319,6 +1360,8 @@ umtx_propagate_priority(struct thread *td) pi = uq->uq_pi_blocked; if (pi == NULL) return; + if (umtx_pi_check_loop(pi)) + return; for (;;) { td = pi->pi_owner; @@ -1362,6 +1405,8 @@ umtx_repropagate_priority(struct umtx_pi *pi) mtx_assert(&umtx_lock, MA_OWNED); + if (umtx_pi_check_loop(pi)) + return; while (pi != NULL && pi->pi_owner != NULL) { pri = PRI_MAX; uq_owner = pi->pi_owner->td_umtxq; @@ -1694,6 +1739,11 @@ do_lock_pi(struct thread *td, struct umutex *m, uint32_t flags, continue; } + if ((owner & ~UMUTEX_CONTESTED) == id) { + error = EDEADLK; + break; + } + if (try != 0) { error = EBUSY; break; |