+static void rcutorture_one_extend(int *readstate, int newstate,
+ struct torture_random_state *trsp)
+{
+ int idxnew = -1;
+ int idxold = *readstate;
+ int statesnew = ~*readstate & newstate;
+ int statesold = *readstate & ~newstate;
+
+ WARN_ON_ONCE(idxold < 0);
+ WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
+
+ /* First, put new protection in place to avoid critical-section gap. */
+ if (statesnew & RCUTORTURE_RDR_BH)
+ local_bh_disable();
+ if (statesnew & RCUTORTURE_RDR_IRQ)
+ local_irq_disable();
+ if (statesnew & RCUTORTURE_RDR_PREEMPT)
+ preempt_disable();
+ if (statesnew & RCUTORTURE_RDR_RCU)
+ idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
+
+ /* Next, remove old protection, irq first due to bh conflict. */
+ if (statesold & RCUTORTURE_RDR_IRQ)
+ local_irq_enable();
+ if (statesold & RCUTORTURE_RDR_BH)
+ local_bh_enable();
+ if (statesold & RCUTORTURE_RDR_PREEMPT)
+ preempt_enable();
+ if (statesold & RCUTORTURE_RDR_RCU)
+ cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
+
+ /* Delay if neither beginning nor end and there was a change. */
+ if ((statesnew || statesold) && *readstate && newstate)
+ cur_ops->read_delay(trsp);
+
+ /* Update the reader state. */
+ if (idxnew == -1)
+ idxnew = idxold & ~RCUTORTURE_RDR_MASK;
+ WARN_ON_ONCE(idxnew < 0);
+ WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
+ *readstate = idxnew | newstate;
+ WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
+ WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
+}
+
+/* Return the biggest extendables mask given current RCU and boot parameters. */
+static int rcutorture_extend_mask_max(void)
+{
+ int mask;
+
+ WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
+ mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
+ mask = mask | RCUTORTURE_RDR_RCU;
+ return mask;
+}
+
+/* Return a random protection state mask, but with at least one bit set. */
+static int
+rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
+{
+ int mask = rcutorture_extend_mask_max();
+ unsigned long randmask1 = torture_random(trsp) >> 8;
+ unsigned long randmask2 = randmask1 >> 1;
+
+ WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
+ /* Half the time lots of bits, half the time only one bit. */
+ if (randmask1 & 0x1)
+ mask = mask & randmask2;
+ else
+ mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
+ if ((mask & RCUTORTURE_RDR_IRQ) &&
+ !(mask & RCUTORTURE_RDR_BH) &&
+ (oldmask & RCUTORTURE_RDR_BH))
+ mask |= RCUTORTURE_RDR_BH; /* Can't enable bh w/irq disabled. */
+ if ((mask & RCUTORTURE_RDR_IRQ) &&
+ !(mask & cur_ops->ext_irq_conflict) &&
+ (oldmask & cur_ops->ext_irq_conflict))
+ mask |= cur_ops->ext_irq_conflict; /* Or if readers object. */
+ return mask ?: RCUTORTURE_RDR_RCU;
+}
+
+/*
+ * Do a randomly selected number of extensions of an existing RCU read-side
+ * critical section.
+ */
+static void rcutorture_loop_extend(int *readstate,
+ struct torture_random_state *trsp)
+{
+ int i;
+ int mask = rcutorture_extend_mask_max();
+
+ WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
+ if (!((mask - 1) & mask))
+ return; /* Current RCU flavor not extendable. */
+ i = (torture_random(trsp) >> 3) & RCUTORTURE_RDR_MAX_LOOPS;
+ while (i--) {
+ mask = rcutorture_extend_mask(*readstate, trsp);
+ rcutorture_one_extend(readstate, mask, trsp);
+ }
+}
+
+/*
+ * Do one read-side critical section, returning false if there was
+ * no data to read. Can be invoked both from process context and
+ * from a timer handler.
+ */
+static bool rcu_torture_one_read(struct torture_random_state *trsp)