rcutorture: Sanitize RCUTORTURE_RDR_MASK

RCUTORTURE_RDR_MASK is currently not the bit indicated by
RCUTORTURE_RDR_SHIFT, but is instead all the bits less significant than
that one.  This is an accident waiting to happen, so this commit makes
RCUTORTURE_RDR_MASK be that one bit and adjusts uses accordingly.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 8b410d982990ce0642d269798e774833f95fb4f5..1e03fe681f0255c7495a424d786dbac7190854af 100644 (file)
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -54,7 +54,7 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@
 
 /* Bits for ->extendables field, extendables param, and related definitions. */
 #define RCUTORTURE_RDR_SHIFT    8      /* Put SRCU index in upper bits. */
-#define RCUTORTURE_RDR_MASK     ((1 << RCUTORTURE_RDR_SHIFT) - 1)
+#define RCUTORTURE_RDR_MASK     (1 << RCUTORTURE_RDR_SHIFT)
 #define RCUTORTURE_RDR_BH       0x01   /* Extend readers by disabling bh. */
 #define RCUTORTURE_RDR_IRQ      0x02   /*  ... disabling interrupts. */
 #define RCUTORTURE_RDR_PREEMPT  0x04   /*  ... disabling preemption. */
@@ -1466,6 +1466,7 @@ static void rcutorture_one_extend(int *readstate, int newstate,
                if (lockit)
                        raw_spin_lock_irqsave(&current->pi_lock, flags);
                cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
+               idxold = 0;
                if (lockit)
                        raw_spin_unlock_irqrestore(&current->pi_lock, flags);
        }
@@ -1476,7 +1477,7 @@ static void rcutorture_one_extend(int *readstate, int newstate,
 
        /* Update the reader state. */
        if (idxnew == -1)
-               idxnew = idxold & ~RCUTORTURE_RDR_MASK;
+               idxnew = idxold & RCUTORTURE_RDR_MASK;
        WARN_ON_ONCE(idxnew < 0);
        WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
        *readstate = idxnew | newstate;
@@ -1626,7 +1627,7 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp, long myid)
                          rcu_torture_writer_state,
                          cookie, cur_ops->get_gp_state());
        rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
-       WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
+       WARN_ON_ONCE(readstate);
        // This next splat is expected behavior if leakpointer, especially
        // for CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels.
        WARN_ON_ONCE(leakpointer && READ_ONCE(p->rtort_pipe_count) > 1);