[S390] Fix kernel preemption.

When returning from IRQ handling and TIF_NEED_RESCHED is set we must
call preempt_schedule_irq() instead of schedule().
Otherwise the BKL might be unlocked in schedule() and therfore
everything that relies on the BKL is broken.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 2 insertions, 10 deletions

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index e15c80efdd05..a3e47b893f07 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -623,15 +623,8 @@ io_preempt:
 io_resume_loop:
         tm      __TI_flags+7(%r9),_TIF_NEED_RESCHED
         jno     io_restore
-        larl    %r1,.Lc_pactive
-        mvc     __TI_precount(4,%r9),0(%r1)
-        TRACE_IRQS_ON
-        stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
-        brasl   %r14,schedule           # call schedule
-        stnsm   __SF_EMPTY(%r15),0xfc   # disable I/O and ext. interrupts
-        TRACE_IRQS_OFF
-        xc      __TI_precount(4,%r9),__TI_precount(%r9)
-        j       io_resume_loop
+        larl    %r14,io_resume_loop
+        jg      preempt_schedule_irq
 #endif
 
 #
@@ -1029,7 +1022,6 @@ cleanup_io_leave_insn:
  */
                 .align  4
 .Lconst:
-.Lc_pactive:    .long   PREEMPT_ACTIVE
 .Lnr_syscalls:  .long   NR_syscalls
 .L0x0130:       .short  0x130
 .L0x0140:       .short  0x140