[PATCH] lockdep: s390 turn validator off in machine-check handler

Machine checks on s390 are always enabled (except in the machine check handler
itself).  Therefore use lockdep_off()/on() in the machine check handler to
avoid deadlocks in the lock validator.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/s390/s390mach.c b/drivers/s390/s390mach.c
index 432136f96e64..ffb3677e354f 100644
--- a/drivers/s390/s390mach.c
+++ b/drivers/s390/s390mach.c
@@ -378,6 +378,8 @@ s390_do_machine_check(struct pt_regs *regs)
         struct mcck_struct *mcck;
         int umode;
 
+        lockdep_off();
+
         mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
         mcck = &__get_cpu_var(cpu_mcck);
         umode = user_mode(regs);
@@ -482,6 +484,7 @@ s390_do_machine_check(struct pt_regs *regs)
                 mcck->warning = 1;
                 set_thread_flag(TIF_MCCK_PENDING);
         }
+        lockdep_on();
 }
 
 /*