linux-stable/include
Linus Torvalds 894076cde7 asm-generic: qspinlock: fix queued_spin_value_unlocked() implementation
[ Upstream commit 125b0bb95d ]

We really don't want to do atomic_read() or anything like that, since we
already have the value, not the lock.  The whole point of this is that
we've loaded the lock from memory, and we want to check whether the
value we loaded was a locked one or not.

The main use of this is the lockref code, which loads both the lock and
the reference count in one atomic operation, and then works on that
combined value.  With the atomic_read(), the compiler would pointlessly
spill the value to the stack, in order to then be able to read it back
"atomically".

This is the qspinlock version of commit c6f4a90022 ("asm-generic:
ticket-lock: Optimize arch_spin_value_unlocked()") which fixed this same
bug for ticket locks.

Cc: Guo Ren <guoren@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/all/CAHk-=whNRv0v6kQiV5QO6DJhjH4KEL36vWQ6Re8Csrnh4zbRkQ@mail.gmail.com/
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-12-20 15:32:37 +01:00
..
acpi ACPICA: actypes.h: Expand the ACPI_ACCESS_ definitions 2022-01-27 09:00:56 +01:00
asm-generic asm-generic: qspinlock: fix queued_spin_value_unlocked() implementation 2023-12-20 15:32:37 +01:00
clocksource
crypto crypto: drbg - make reseeding from get_random_bytes() synchronous 2022-06-25 11:46:41 +02:00
drm drm/mipi-dsi: Fix byte order of 16-bit DCS set/get brightness 2023-03-11 16:26:39 +01:00
dt-bindings dt-bindings: reset: meson8b: fix duplicate reset IDs 2020-01-23 08:20:29 +01:00
keys KEYS: Don't write out to userspace while holding key semaphore 2020-04-24 08:01:25 +02:00
kvm KVM: arm/arm64: Sync ICH_VMCR_EL2 back when about to block 2019-08-25 10:50:18 +02:00
linux cred: switch to using atomic_long_t 2023-12-20 15:32:35 +01:00
math-emu math-emu/soft-fp.h: (_FP_ROUND_ZERO) cast 0 to void to fix warning 2019-12-17 20:38:02 +01:00
media media: v4l2-mem2mem: add lock to protect parameter num_rdy 2023-08-30 16:35:10 +02:00
memory
misc
net drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group 2023-12-13 16:46:18 +01:00
pcmcia pcmcia/ds.h: introduce helper for pcmcia_driver module boilerplate 2013-03-15 12:26:03 -07:00
ras
rdma RDMA/netlink: Add __maybe_unused to static inline in C file 2021-11-26 11:40:41 +01:00
scsi scsi: core: Use 32-bit hostnum in scsi_host_lookup() 2023-09-23 10:46:58 +02:00
soc irqchip/eznps: Fix build error for !ARC700 builds 2020-09-23 10:46:27 +02:00
sound ALSA: core: Add async signal helpers 2022-08-25 11:11:37 +02:00
target scsi: target: Fix ordered tag handling 2021-11-26 11:40:38 +01:00
trace f2fs: Fix f2fs_truncate_partial_nodes ftrace event 2023-04-26 11:18:56 +02:00
uapi gtp: uapi: fix GTPA_MAX 2023-11-08 11:21:06 +01:00
video video: of_display_timing.h: include errno.h 2022-07-12 16:27:28 +02:00
xen xen/gnttab: fix gnttab_end_foreign_access() without page specified 2022-03-11 10:13:33 +01:00