Revert: "powerpc/tm: Check for already reclaimed tasks"

BugLink: http://bugs.launchpad.net/bugs/1580754

This reverts commit e924c60d which was
commit 7f821fc9 upstream.

It shouldn't have been applied as the original was already in 4.4.
Reported-by: Jiri Slaby <jslaby@suse.cz>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

arch/powerpc/kernel/process.c

@@ -551,24 +551,6 @@ static void tm_reclaim_thread(struct thread_struct *thr,
 		msr_diff &= MSR_FP | MSR_VEC | MSR_VSX | MSR_FE0 | MSR_FE1;
 	}
 
-	/*
-	 * Use the current MSR TM suspended bit to track if we have
-	 * checkpointed state outstanding.
-	 * On signal delivery, we'd normally reclaim the checkpointed
-	 * state to obtain stack pointer (see:get_tm_stackpointer()).
-	 * This will then directly return to userspace without going
-	 * through __switch_to(). However, if the stack frame is bad,
-	 * we need to exit this thread which calls __switch_to() which
-	 * will again attempt to reclaim the already saved tm state.
-	 * Hence we need to check that we've not already reclaimed
-	 * this state.
-	 * We do this using the current MSR, rather tracking it in
-	 * some specific thread_struct bit, as it has the additional
-	 * benifit of checking for a potential TM bad thing exception.
-	 */
-	if (!MSR_TM_SUSPENDED(mfmsr()))
-		return;
-
 	/*
 	 * Use the current MSR TM suspended bit to track if we have
 	 * checkpointed state outstanding.