mirror-linux/include
Sebastian Andrzej Siewior 3c118547f8 u64_stats: Disable preemption on 32bit UP+SMP PREEMPT_RT during updates.
On PREEMPT_RT the seqcount_t for synchronisation is required on 32bit
architectures even on UP because the softirq (and the threaded IRQ handler) can
be preempted.

With the seqcount_t for synchronisation, a reader with higher priority can
preempt the writer and then spin endlessly in read_seqcount_begin() while the
writer can't make progress.

To avoid such a lock up on PREEMPT_RT the writer must disable preemption during
the update. There is no need to disable interrupts because no writer is using
this API in hard-IRQ context on PREEMPT_RT.

Disable preemption on 32bit-RT within the u64_stats write section.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-12-13 12:42:08 +00:00
..
acpi Merge branches 'acpica', 'acpi-ec', 'acpi-pmic' and 'acpi-video' 2021-11-10 14:03:14 +01:00
asm-generic Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-11-26 13:45:19 -08:00
clocksource
crypto
drm Removed the TTM Huge Page functionnality to address a crash, a timeout 2021-11-11 08:14:19 +10:00
dt-bindings dt-bindings: Rename Ingenic CGU headers to ingenic,*.h 2021-11-11 22:27:14 -06:00
keys
kunit
kvm
linux u64_stats: Disable preemption on 32bit UP+SMP PREEMPT_RT during updates. 2021-12-13 12:42:08 +00:00
math-emu
media Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
memory
misc
net bareudp: Move definition of struct bareudp_conf to bareudp.c 2021-12-13 12:34:09 +00:00
pcmcia
ras
rdma RDMA/netlink: Add __maybe_unused to static inline in C file 2021-11-16 13:13:08 -04:00
scsi SCSI misc on 20211112 2021-11-12 12:25:50 -08:00
soc net: ocelot: add FDMA support 2021-12-10 20:56:58 -08:00
sound ASoC: Fixes for v5.16 2021-11-25 14:35:24 +01:00
target
trace NFS client bugfixes for Linux 5.16 2021-11-27 10:33:55 -08:00
uapi Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-12-10 15:56:13 -08:00
vdso
video
xen xen: add "not_essential" flag to struct xenbus_driver 2021-11-23 13:41:29 -06:00