kernel/linux.git/lib/atomic64.c, branch v6.12.80

atomic64: Use arch_spin_locks instead of raw_spin_locks

2025-02-17T09:05:14+00:00

commit 6c8ad3ab45ad0e94bfb7a9c71f2fa9c6cacea4b2 upstream. raw_spin_locks can be traced by lockdep or tracing itself. Atomic64 operations can be used in the tracing infrastructure. When an architecture does not have true atomic64 operations it can use the generic version that disables interrupts and uses spin_locks. The tracing ring buffer code uses atomic64 operations for the time keeping. But because some architectures use the default operations, the locking inside the atomic operations can cause an infinite recursion. As atomic64 implementation is architecture specific, it should not be using raw_spin_locks() but instead arch_spin_locks as that is the purpose of arch_spin_locks. To be used in architecture specific implementations of generic infrastructure like atomic64 operations. Note, by switching from raw_spin_locks to arch_spin_locks, the locks taken to emulate the atomic64 operations will not have lockdep, mmio, or any kind of checks done on them. They will not even disable preemption, although the code will disable interrupts preventing the tasks that hold the locks from being preempted. As the locks held are done so for very short periods of time, and the logic is only done to emulate atomic64, not having them be instrumented should not be an issue. Cc: stable@vger.kernel.org Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Linus Torvalds Cc: Andreas Larsson Link: https://lore.kernel.org/20250122144311.64392baf@gandalf.local.home Fixes: c84897c0ff592 ("ring-buffer: Remove 32bit timestamp logic") Closes: https://lore.kernel.org/all/86fb4f86-a0e4-45a2-a2df-3154acc4f086@gaisler.com/ Reported-by: Ludwig Rydberg Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman

locking/atomic: atomic64: Remove unusable atomic ops

2021-12-13T09:56:09+00:00

The generic atomic64 implementation provides: * atomic64_and_return() * atomic64_or_return() * atomic64_xor_return() ... but none of these exist in the standard atomic64 API as described by scripts/atomic/atomics.tbl, and none of these have prototypes exposed by . The lkp kernel test robot noted this results in warnings when building with W=1: lib/atomic64.c:82:5: warning: no previous prototype for 'generic_atomic64_and_return' [-Wmissing-prototypes] lib/atomic64.c:82:5: warning: no previous prototype for 'generic_atomic64_or_return' [-Wmissing-prototypes] lib/atomic64.c:82:5: warning: no previous prototype for 'generic_atomic64_xor_return' [-Wmissing-prototypes] This appears to have been a thinko in commit: 28aa2bda2211f432 ("locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()") ... where we grouped add/sub separately from and/ox/xor, so that we could avoid implementing _return forms for the latter group, but forgot to remove ATOMIC64_OP_RETURN() for that group. This doesn't cause any functional problem, but it's pointless to build code which cannot be used. Remove the unusable code. This does not affect add/sub, for which _return forms will still be built. Reported-by: kernel test robot Signed-off-by: Mark Rutland Signed-off-by: Peter Zijlstra (Intel) Acked-by: Boqun Feng Link: https://lore.kernel.org/r/20211126115923.41489-1-mark.rutland@arm.com

locking/atomic: atomic64: support ARCH_ATOMIC

2021-05-26T11:20:50+00:00

We'd like all architectures to convert to ARCH_ATOMIC, as this will enable functionality, and once all architectures are converted it will be possible to make significant cleanups to the atomic headers. A number of architectures use asm-generic/atomic64.h, and it's impractical to convert the header and all these architectures in one go. To make it possible to convert them one-by-one, let's make the asm-generic implementation function as either atomic64_*() or arch_atomic64_*() depending on whether ARCH_ATOMIC is selected. To do this, the generic implementations are prefixed as generic_atomic64_*(), and preprocessor definitions map atomic64_*()/arch_atomic64_*() onto these as appropriate. Once all users are moved over to ARCH_ATOMIC the ifdeffery in the header can be simplified and/or removed entirely. For existing users (none of which select ARCH_ATOMIC), there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland Cc: Arnd Bergmann Cc: Boqun Feng Cc: Peter Zijlstra Cc: Will Deacon Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210525140232.53872-11-mark.rutland@arm.com

locking/atomic: Use s64 for atomic64

2019-06-03T10:32:56+00:00

As a step towards making the atomic64 API use consistent types treewide, let's have the generic atomic64 implementation use s64 as the underlying type for atomic64_t, rather than long long, matching the generated headers. Otherwise, there should be no functional change as a result of this patch. Signed-off-by: Mark Rutland Signed-off-by: Peter Zijlstra (Intel) Acked-by: Arnd Bergmann Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: aou@eecs.berkeley.edu Cc: bp@alien8.de Cc: catalin.marinas@arm.com Cc: davem@davemloft.net Cc: fenghua.yu@intel.com Cc: heiko.carstens@de.ibm.com Cc: herbert@gondor.apana.org.au Cc: ink@jurassic.park.msu.ru Cc: jhogan@kernel.org Cc: linux@armlinux.org.uk Cc: mattst88@gmail.com Cc: mpe@ellerman.id.au Cc: palmer@sifive.com Cc: paul.burton@mips.com Cc: paulus@samba.org Cc: ralf@linux-mips.org Cc: rth@twiddle.net Cc: tony.luck@intel.com Cc: vgupta@synopsys.com Link: https://lkml.kernel.org/r/20190522132250.26499-4-mark.rutland@arm.com Signed-off-by: Ingo Molnar

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

atomics/generic: Define atomic64_fetch_add_unless()

2018-06-21T12:25:21+00:00

As a step towards unifying the atomic/atomic64/atomic_long APIs, this patch converts the generic implementation of atomic64_add_unless() into a generic implementation of atomic64_fetch_add_unless(). A wrapper in will build atomic_add_unless() atop of this, provided it is given a preprocessor definition. No functional change is intended as a result of this patch. Signed-off-by: Mark Rutland Reviewed-by: Will Deacon Acked-by: Peter Zijlstra (Intel) Cc: Arnd Bergmann Cc: Boqun Feng Cc: Linus Torvalds Cc: Thomas Gleixner Link: https://lore.kernel.org/lkml/20180621121321.4761-9-mark.rutland@arm.com Signed-off-by: Ingo Molnar

atomics: Make conditional ops return 'bool'

2018-06-21T12:22:33+00:00

Some of the atomics return a status value, which is a boolean value describing whether the operation was performed. To make it clear that this is a boolean value, let's update the common fallbacks to return bool, fixing up the return values and comments likewise. At the same time, let's simplify the description of the operations in their respective comments. The instrumented atomics and generic atomic64 implementation are updated accordingly. Note that atomic64_dec_if_positive() doesn't follow the usual test op pattern, and returns the would-be decremented value. This is not changed. Signed-off-by: Mark Rutland Reviewed-by: Will Deacon Acked-by: Peter Zijlstra (Intel) Cc: Boqun Feng Cc: Linus Torvalds Cc: Michael Ellerman Cc: Thomas Gleixner Link: https://lore.kernel.org/lkml/20180621121321.4761-5-mark.rutland@arm.com Signed-off-by: Ingo Molnar

locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()

2016-06-16T08:48:32+00:00

Now that all the architectures have implemented support for these new atomic primitives add on the generic infrastructure to expose and use it. Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Arnd Bergmann Cc: Boqun Feng Cc: Borislav Petkov Cc: Davidlohr Bueso Cc: Frederic Weisbecker Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

atomic: Provide atomic_{or,xor,and}

2015-07-27T12:06:24+00:00

Implement atomic logic ops -- atomic_{or,xor,and}. These will replace the atomic_{set,clear}_mask functions that are available on some archs. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner

locking,arch: Rewrite generic atomic support

2014-08-14T10:48:14+00:00

Rewrite generic atomic support to only require cmpxchg(), generate all other primitives from that. Furthermore reduce the endless repetition for all these primitives to a few CPP macros. This way we get more for less lines. Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140508135852.940119622@infradead.org Cc: Arnd Bergmann Cc: David Howells Cc: Paul E. McKenney Cc: David S. Miller Cc: Linus Torvalds Cc: linux-arch@vger.kernel.org Signed-off-by: Ingo Molnar