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From: Andrea Parri <andrea.parri@amarulasolutions.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
	will.deacon@arm.com, aou@eecs.berkeley.edu, arnd@arndb.de,
	bp@alien8.de, catalin.marinas@arm.com, davem@davemloft.net,
	fenghua.yu@intel.com, heiko.carstens@de.ibm.com,
	herbert@gondor.apana.org.au, ink@jurassic.park.msu.ru,
	jhogan@kernel.org, linux@armlinux.org.uk, mattst88@gmail.com,
	mingo@kernel.org, mpe@ellerman.id.au, palmer@sifive.com,
	paul.burton@mips.com, paulus@samba.org, ralf@linux-mips.org,
	rth@twiddle.net, stable@vger.kernel.org, tglx@linutronix.de,
	tony.luck@intel.com, vgupta@synopsys.com
Subject: Re: [PATCH 00/18] locking/atomic: atomic64 type cleanup
Date: Thu, 23 May 2019 10:30:13 +0200	[thread overview]
Message-ID: <20190523083013.GA4616@andrea> (raw)
In-Reply-To: <20190522132250.26499-1-mark.rutland@arm.com>

Hi Mark,

On Wed, May 22, 2019 at 02:22:32PM +0100, Mark Rutland wrote:
> Currently architectures return inconsistent types for atomic64 ops. Some return
> long (e..g. powerpc), some return long long (e.g. arc), and some return s64
> (e.g. x86).

(only partially related, but probably worth asking:)

While reading the series, I realized that the following expression:

	atomic64_t v;
        ...
	typeof(v.counter) my_val = atomic64_set(&v, VAL);

is a valid expression on some architectures (in part., on architectures
which #define atomic64_set() to WRITE_ONCE()) but is invalid on others.
(This is due to the fact that WRITE_ONCE() can be used as an rvalue in
the above assignment; TBH, I ignore the reasons for having such rvalue?)

IIUC, similar considerations hold for atomic_set().

The question is whether this is a known/"expected" inconsistency in the
implementation of atomic64_set() or if this would also need to be fixed
/addressed (say in a different patchset)?

Thanks,
  Andrea

  parent reply	other threads:[~2019-05-23  8:30 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22 13:22 Mark Rutland
2019-05-22 13:22 ` [PATCH 01/18] locking/atomic: crypto: nx: prepare for atomic64_read() conversion Mark Rutland
2019-06-03 13:34   ` [tip:locking/core] locking/atomic, crypto/nx: Prepare " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 02/18] locking/atomic: s390/pci: prepare " Mark Rutland
2019-06-03 13:34   ` [tip:locking/core] locking/atomic, s390/pci: Prepare " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 03/18] locking/atomic: generic: use s64 for atomic64 Mark Rutland
2019-05-22 21:16   ` Arnd Bergmann
2019-06-03 13:35   ` [tip:locking/core] locking/atomic: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 04/18] locking/atomic: alpha: use " Mark Rutland
2019-06-03 13:36   ` [tip:locking/core] locking/atomic, alpha: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 05/18] locking/atomic: arc: use " Mark Rutland
2019-05-23 23:10   ` Vineet Gupta
2019-06-03 13:36   ` [tip:locking/core] locking/atomic, arc: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 06/18] locking/atomic: arm: use " Mark Rutland
2019-06-03 13:37   ` [tip:locking/core] locking/atomic, arm: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 07/18] locking/atomic: arm64: use " Mark Rutland
2019-06-03 13:38   ` [tip:locking/core] locking/atomic, arm64: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 08/18] locking/atomic: ia64: use " Mark Rutland
2019-06-03 13:39   ` [tip:locking/core] locking/atomic, ia64: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 09/18] locking/atomic: mips: use " Mark Rutland
2019-06-03 13:39   ` [tip:locking/core] locking/atomic, mips: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 10/18] locking/atomic: powerpc: use " Mark Rutland
2019-05-23 13:27   ` Michael Ellerman
2019-06-03 13:40   ` [tip:locking/core] locking/atomic, powerpc: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 11/18] locking/atomic: riscv: fix atomic64_sub_if_positive() offset argument Mark Rutland
2019-05-22 19:06   ` Palmer Dabbelt
2019-06-03 13:41   ` [tip:locking/core] locking/atomic, riscv: Fix " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 12/18] locking/atomic: riscv: use s64 for atomic64 Mark Rutland
2019-05-22 19:06   ` Palmer Dabbelt
2019-05-23 10:23     ` Mark Rutland
2019-06-03 13:41   ` [tip:locking/core] locking/atomic, riscv: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 13/18] locking/atomic: s390: use " Mark Rutland
2019-06-03 13:42   ` [tip:locking/core] locking/atomic, s390: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 14/18] locking/atomic: sparc: use " Mark Rutland
2019-06-03 13:43   ` [tip:locking/core] locking/atomic, sparc: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 15/18] locking/atomic: x86: use " Mark Rutland
2019-06-03 13:44   ` [tip:locking/core] locking/atomic, x86: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 16/18] locking/atomic: use s64 for atomic64_t on 64-bit Mark Rutland
2019-06-03 13:44   ` [tip:locking/core] locking/atomic: Use " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 17/18] locking/atomic: crypto: nx: remove redundant casts Mark Rutland
2019-06-03 13:45   ` [tip:locking/core] locking/atomic, crypto/nx: Remove " tip-bot for Mark Rutland
2019-05-22 13:22 ` [PATCH 18/18] locking/atomic: s390/pci: remove " Mark Rutland
2019-06-03 13:46   ` [tip:locking/core] locking/atomic, s390/pci: Remove " tip-bot for Mark Rutland
2019-05-22 21:18 ` [PATCH 00/18] locking/atomic: atomic64 type cleanup Arnd Bergmann
2019-05-23 10:28   ` Mark Rutland
2019-05-23  8:30 ` Andrea Parri [this message]
2019-05-23 10:19   ` Mark Rutland
2019-05-23 11:20     ` Andrea Parri
2019-05-24 10:37     ` Peter Zijlstra
2019-05-24 11:18       ` Peter Zijlstra
2019-05-24 11:38         ` Greg KH
2019-05-24 11:42         ` Will Deacon
2019-05-24 11:52           ` Peter Zijlstra
2019-05-24 22:43             ` Andrea Parri
2019-05-28 10:47               ` Peter Zijlstra
2019-05-28 11:15                 ` Andrea Parri
2019-06-03 13:46             ` [tip:locking/core] Documentation/atomic_t.txt: Clarify pure non-rmw usage tip-bot for Peter Zijlstra
2019-06-06  8:44               ` Andrea Parri
2019-06-06  9:04                 ` Peter Zijlstra
2019-06-06  9:11                   ` Andrea Parri

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