From: Peter Zijlstra <peterz@infradead.org>
To: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Cc: linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org,
linux-arch@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
Boqun Feng <boqun.feng@gmail.com>,
Russell King <linux@armlinux.org.uk>,
Arnd Bergmann <arnd@arndb.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Darren Hart <dvhart@infradead.org>, Shuah Khan <shuah@kernel.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Josh Triplett <josh@joshtriplett.org>,
Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
David Laight <David.Laight@ACULAB.COM>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] atomic{64}_t: Explicitly specify data storage length and alignment
Date: Mon, 9 Jul 2018 15:35:42 +0200 [thread overview]
Message-ID: <20180709133542.GP2476@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180709124741.21037-1-abrodkin@synopsys.com>
On Mon, Jul 09, 2018 at 03:47:41PM +0300, Alexey Brodkin wrote:
> diff --git a/include/asm-generic/atomic64.h b/include/asm-generic/atomic64.h
> index 8d28eb010d0d..b94b749b5952 100644
> --- a/include/asm-generic/atomic64.h
> +++ b/include/asm-generic/atomic64.h
> @@ -13,7 +13,7 @@
> #define _ASM_GENERIC_ATOMIC64_H
>
> typedef struct {
> - long long counter;
> + u64 __aligned(8) counter;
> } atomic64_t;
The type is wrong, atomic is signed, the alignment also really doesn't
matter, generic atomic64 is utter crap.
> #define ATOMIC64_INIT(i) { (i) }
> diff --git a/include/linux/types.h b/include/linux/types.h
> index 9834e90aa010..e2f631782621 100644
> --- a/include/linux/types.h
> +++ b/include/linux/types.h
> @@ -174,12 +174,12 @@ typedef phys_addr_t resource_size_t;
> typedef unsigned long irq_hw_number_t;
>
> typedef struct {
> - int counter;
> + u32 __aligned(4) counter;
> } atomic_t;
u32 is wrong, the atomic type is signed.
Also, if an architecture doesn't properly align its native machine word
size but requires alignment for atomics it's a broken architecture.
>
> #ifdef CONFIG_64BIT
> typedef struct {
> - long counter;
> + u64 __aligned(8) counter;
> } atomic64_t;
> #endif
>
Similar for this one, on 64bit archs that support atomics the native
64bit types (long included) had better already imply this alignment.
next prev parent reply other threads:[~2018-07-09 13:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-09 12:47 [PATCH] atomic{64}_t: Explicitly specify data storage length and alignment Alexey Brodkin
2018-07-09 12:55 ` Geert Uytterhoeven
2018-07-09 13:07 ` Will Deacon
2018-07-09 13:30 ` David Laight
2018-07-09 13:49 ` Geert Uytterhoeven
2018-07-09 13:35 ` Peter Zijlstra [this message]
2018-07-09 14:30 ` Alexey Brodkin
2018-07-09 14:45 ` Peter Zijlstra
2018-07-09 14:04 ` Russell King - ARM Linux
2018-07-09 16:25 ` kbuild test robot
2018-07-09 18:05 ` kbuild test robot
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