locking/rwsem: Disable preemption in all down_write*() and up_write() code paths

jira LE-1907
Rebuild_History Non-Buildable kernel-rt-5.14.0-284.30.1.rt14.315.el9_2
commit-author Waiman Long <longman@redhat.com>
commit 1d61659
Empty-Commit: Cherry-Pick Conflicts during history rebuild.
Will be included in final tarball splat. Ref for failed cherry-pick at:
ciq/ciq_backports/kernel-rt-5.14.0-284.30.1.rt14.315.el9_2/1d61659c.failed

The previous patch has disabled preemption in all the down_read() and
up_read() code paths. For symmetry, this patch extends commit:

  48dfb5d ("locking/rwsem: Disable preemption while trying for rwsem lock")

... to have preemption disabled in all the down_write() and up_write()
code paths, including downgrade_write().

	Suggested-by: Peter Zijlstra <peterz@infradead.org>
	Signed-off-by: Waiman Long <longman@redhat.com>
	Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126003628.365092-4-longman@redhat.com
(cherry picked from commit 1d61659)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

# Conflicts:
#	kernel/locking/rwsem.c

Author: PlaidCat

ciq/ciq_backports/kernel-rt-5.14.0-284.30.1.rt14.315.el9_2/1d61659c.failed

@@ -0,0 +1,91 @@
+locking/rwsem: Disable preemption in all down_write*() and up_write() code paths
+
+jira LE-1907
+Rebuild_History Non-Buildable kernel-rt-5.14.0-284.30.1.rt14.315.el9_2
+commit-author Waiman Long <longman@redhat.com>
+commit 1d61659ced6bd8881cf2fb5cbcb28f9541fc7430
+Empty-Commit: Cherry-Pick Conflicts during history rebuild.
+Will be included in final tarball splat. Ref for failed cherry-pick at:
+ciq/ciq_backports/kernel-rt-5.14.0-284.30.1.rt14.315.el9_2/1d61659c.failed
+
+The previous patch has disabled preemption in all the down_read() and
+up_read() code paths. For symmetry, this patch extends commit:
+
+  48dfb5d2560d ("locking/rwsem: Disable preemption while trying for rwsem lock")
+
+... to have preemption disabled in all the down_write() and up_write()
+code paths, including downgrade_write().
+
+	Suggested-by: Peter Zijlstra <peterz@infradead.org>
+	Signed-off-by: Waiman Long <longman@redhat.com>
+	Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Link: https://lore.kernel.org/r/20230126003628.365092-4-longman@redhat.com
+(cherry picked from commit 1d61659ced6bd8881cf2fb5cbcb28f9541fc7430)
+	Signed-off-by: Jonathan Maple <jmaple@ciq.com>
+
+# Conflicts:
+#	kernel/locking/rwsem.c
+diff --cc kernel/locking/rwsem.c
+index 6e9b6fe29f61,acb5a50309a1..000000000000
+--- a/kernel/locking/rwsem.c
++++ b/kernel/locking/rwsem.c
+@@@ -1093,51 -1167,17 +1085,54 @@@ rwsem_down_write_slowpath(struct rw_sem
+  		 * In this case, we attempt to acquire the lock again
+  		 * without sleeping.
+  		 */
+ -		if (waiter.handoff_set) {
+ +		if (wstate == WRITER_HANDOFF) {
+  			enum owner_state owner_state;
+  
+- 			preempt_disable();
+  			owner_state = rwsem_spin_on_owner(sem);
+- 			preempt_enable();
+- 
+  			if (owner_state == OWNER_NULL)
+  				goto trylock_again;
+  		}
+  
+++<<<<<<< HEAD
+ +		/* Block until there are no active lockers. */
+ +		for (;;) {
+ +			if (signal_pending_state(state, current))
+ +				goto out_nolock;
+ +
+ +			schedule();
+ +			lockevent_inc(rwsem_sleep_writer);
+ +			set_current_state(state);
+ +			/*
+ +			 * If HANDOFF bit is set, unconditionally do
+ +			 * a trylock.
+ +			 */
+ +			if (wstate == WRITER_HANDOFF)
+ +				break;
+ +
+ +			if ((wstate == WRITER_NOT_FIRST) &&
+ +			    (rwsem_first_waiter(sem) == &waiter))
+ +				wstate = WRITER_FIRST;
+ +
+ +			count = atomic_long_read(&sem->count);
+ +			if (!(count & RWSEM_LOCK_MASK))
+ +				break;
+ +
+ +			/*
+ +			 * The setting of the handoff bit is deferred
+ +			 * until rwsem_try_write_lock() is called.
+ +			 */
+ +			if ((wstate == WRITER_FIRST) && (rt_task(current) ||
+ +			    time_after(jiffies, waiter.timeout))) {
+ +				wstate = WRITER_HANDOFF;
+ +				lockevent_inc(rwsem_wlock_handoff);
+ +				break;
+ +			}
+ +		}
+++=======
++ 		schedule_preempt_disabled();
++ 		lockevent_inc(rwsem_sleep_writer);
++ 		set_current_state(state);
+++>>>>>>> 1d61659ced6b (locking/rwsem: Disable preemption in all down_write*() and up_write() code paths)
+  trylock_again:
+  		raw_spin_lock_irq(&sem->wait_lock);
+  	}
+* Unmerged path kernel/locking/rwsem.c