[PATCH v2 4/4] powerpc/tm: Do not recheckpoint non-tm task

[Breno Leitao <leitao@debian.org>]

If __switch_to() tries to context switch from task A to task B, and task A
 had task->thread->regs->msr[TM] enabled, then __switch_to_tm() will call
tm_recheckpoint_new_task(), which will call trecheckpoint, for task B, which
 is clearly wrong since task B might not be an active TM user.

This does not cause a lot of damage because tm_recheckpoint() will abort
the call since it realize that the current task does not have msr[TM] bit
set.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 arch/powerpc/kernel/process.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f8beee03f00a..d26a150766ef 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1036,7 +1036,8 @@ static inline void __switch_to_tm(struct task_struct *prev,
 				prev->thread.regs->msr &= ~MSR_TM;
 		}
 
-		tm_recheckpoint_new_task(new);
+		if (tm_enabled(new))
+			tm_recheckpoint_new_task(new);
 	}
 }
 
-- 
2.16.3