Matija Glavinic Pecotic 6f542ebeae MIPS: Fix race on setting and getting cpu_online_mask ... While testing cpu hoptlug (cpu down and up in loops) on kernel 4.4, it was observed that occasionally check for cpu online will fail in kernel/cpu.c, _cpu_up: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/kernel/cpu.c?h=v4.4.79#n485 518 /* Arch-specific enabling code. */ 519 ret = __cpu_up(cpu, idle); 520 521 if (ret != 0) 522 goto out_notify; 523 BUG_ON(!cpu_online(cpu)); Reason is race between start_secondary and _cpu_up. cpu_callin_map is set before cpu_online_mask. In __cpu_up, cpu_callin_map is waited for, but cpu online mask is not, resulting in race in which secondary processor started and set cpu_callin_map, but not yet set the online mask,resulting in above BUG being hit. Upstream differs in the area. cpu_online check is in bringup_wait_for_ap, which is after cpu reached AP_ONLINE_IDLE,where secondary passed its start function. Nonetheless, fix makes start_secondary safe and not depending on other locks throughout the code. It protects as well against cpu_online checks put in between sometimes in the future. Fix this by moving completion after all flags are set. Signed-off-by: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nokia.com> Cc: Alexander Sverdlin <alexander.sverdlin@nokia.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/16925/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>		2017-08-07 11:57:30 +02:00
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8250-platform.c
asm-offsets.c
binfmt_elfn32.c
binfmt_elfo32.c
bmips_5xxx_init.S
bmips_vec.S
branch.c
cacheinfo.c
cevt-bcm1480.c
cevt-ds1287.c
cevt-gt641xx.c
cevt-r4k.c
cevt-sb1250.c
cevt-txx9.c
cmpxchg.c
cps-vec-ns16550.S
cps-vec.S
cpu-bugs64.c
cpu-probe.c
crash_dump.c
crash.c
csrc-bcm1480.c
csrc-ioasic.c
csrc-r4k.c
csrc-sb1250.c
early_printk_8250.c
early_printk.c
elf.c
entry.S
ftrace.c
genex.S
gpio_txx9.c
head.S
i8253.c
idle.c
irq_txx9.c
irq-gt641xx.c
irq-msc01.c
irq-rm7000.c
irq.c
jump_label.c
kgdb.c
kprobes.c
linux32.c
machine_kexec.c
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mcount.S
mips_machine.c
mips-cm.c
mips-cpc.c
mips-mt-fpaff.c
mips-mt.c
mips-r2-to-r6-emul.c
module.c
octeon_switch.S
perf_event_mipsxx.c
perf_event.c
pm-cps.c
pm.c
probes-common.h
proc.c
process.c
prom.c
ptrace32.c
ptrace.c
r4k_fpu.S
r4k_switch.S
r2300_fpu.S
r2300_switch.S
r6000_fpu.S
relocate_kernel.S
relocate.c
reset.c
rtlx-cmp.c
rtlx-mt.c
rtlx.c
scall32-o32.S
scall64-64.S
scall64-n32.S
scall64-o32.S
segment.c
setup.c
signal32.c
signal_n32.c
signal_o32.c
signal-common.h
signal.c
smp-bmips.c
smp-cmp.c
smp-cps.c
smp-mt.c
smp-up.c
smp.c
spinlock_test.c
spram.c
stacktrace.c
sync-r4k.c
syscall.c
sysrq.c
time.c
topology.c
traps.c
unaligned.c
uprobes.c
vdso.c
vmlinux.lds.S
vpe-cmp.c
vpe-mt.c
vpe.c
watch.c