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Commit b8e7a54c authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

[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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 37e3a6ac

arch/s390/kernel/entry.S

+5 −10
Original line number Diff line number Diff line
@@ -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

arch/s390/kernel/entry64.S

+2 −10
Original line number Diff line number Diff line
@@ -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