[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>

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 764d561..b2b2edc 100644 (file)
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -640,15 +640,9 @@ io_preempt:
 io_resume_loop:
        tm      __TI_flags+3(%r9),_TIF_NEED_RESCHED
        bno     BASED(io_restore)
-       mvc     __TI_precount(4,%r9),BASED(.Lc_pactive)
-       TRACE_IRQS_ON
-       stosm   __SF_EMPTY(%r15),0x03  # reenable interrupts
-       l       %r1,BASED(.Lschedule)
-       basr    %r14,%r1               # call schedule
-       stnsm   __SF_EMPTY(%r15),0xfc  # disable I/O and ext. interrupts
-       TRACE_IRQS_OFF
-       xc      __TI_precount(4,%r9),__TI_precount(%r9)
-       b       BASED(io_resume_loop)
+       l       %r1,BASED(.Lpreempt_schedule_irq)
+       la      %r14,BASED(io_resume_loop)
+       br      %r1                     # call schedule
 #endif
 
 #
@@ -1062,7 +1056,6 @@ cleanup_io_leave_insn:
                .align  4
 .Lc_spsize:    .long   SP_SIZE
 .Lc_overhead:  .long   STACK_FRAME_OVERHEAD
-.Lc_pactive:   .long   PREEMPT_ACTIVE
 .Lnr_syscalls: .long   NR_syscalls
 .L0x018:       .short  0x018
 .L0x020:       .short  0x020
@@ -1086,6 +1079,8 @@ cleanup_io_leave_insn:
 .Lexecve_tail: .long   execve_tail
 .Ljump_table:  .long   pgm_check_table
 .Lschedule:    .long   schedule
+.Lpreempt_schedule_irq:
+               .long   preempt_schedule_irq
 .Ltrace:       .long   syscall_trace
 .Lschedtail:   .long   schedule_tail
 .Lsysc_table:  .long   sys_call_table

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index e15c80e..a3e47b8 100644 (file)
--- 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