diff options
| -rw-r--r-- | sys/kern/subr_witness.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/sys/kern/subr_witness.c b/sys/kern/subr_witness.c index dc343d0..1280807 100644 --- a/sys/kern/subr_witness.c +++ b/sys/kern/subr_witness.c @@ -1170,19 +1170,25 @@ witness_checkorder(struct lock_object *lock, int flags, const char *file, /* * Try to perform most checks without a lock. If this succeeds we - * can skip acquiring the lock and return success. + * can skip acquiring the lock and return success. Otherwise we redo + * the check with the lock held to handle races with concurrent updates. */ w1 = plock->li_lock->lo_witness; if (witness_lock_order_check(w1, w)) return; + mtx_lock_spin(&w_mtx); + if (witness_lock_order_check(w1, w)) { + mtx_unlock_spin(&w_mtx); + return; + } + witness_lock_order_add(w1, w); + /* * Check for duplicate locks of the same type. Note that we only * have to check for this on the last lock we just acquired. Any * other cases will be caught as lock order violations. */ - mtx_lock_spin(&w_mtx); - witness_lock_order_add(w1, w); if (w1 == w) { i = w->w_index; if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && @@ -1996,7 +2002,10 @@ _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) /* The flags on one better be the inverse of the flags on the other */ if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || - (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { + (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { + /* Don't squawk if we're potentially racing with an update. */ + if (!mtx_owned(&w_mtx)) + return (0); printf("%s: rmatrix mismatch between %s (index %d) and %s " "(index %d): w_rmatrix[%d][%d] == %hhx but " "w_rmatrix[%d][%d] == %hhx\n", |
