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From: Waiman Long <longman@redhat.com>
To: Arnd Bergmann <arnd@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>
Cc: Jonas Bonn <jonas@southpole.se>,
	linux-s390@vger.kernel.org,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	linux-ia64@vger.kernel.org, Vasily Gorbik <gor@linux.ibm.com>,
	Arnd Bergmann <arnd@arndb.de>, Boqun Feng <boqun.feng@gmail.com>,
	linux-kernel@vger.kernel.org,
	Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	openrisc@lists.librecores.org, Paul Mackerras <paulus@samba.org>,
	linux-parisc@vger.kernel.org, Stafford Horne <shorne@gmail.com>,
	linuxppc-dev@lists.ozlabs.org, Helge Deller <deller@gmx.de>,
	Heiko Carstens <hca@linux.ibm.com>
Subject: Re: [PATCH] locking: remove spin_lock_flags() etc
Date: Fri, 22 Oct 2021 21:37:22 -0400	[thread overview]
Message-ID: <cc8e3c58-457d-fdf3-6a62-98bde0cefdea@redhat.com> (raw)
In-Reply-To: <20211022120058.1031690-1-arnd@kernel.org>

On 10/22/21 7:59 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> parisc, ia64 and powerpc32 are the only remaining architectures that
> provide custom arch_{spin,read,write}_lock_flags() functions, which are
> meant to re-enable interrupts while waiting for a spinlock.
>
> However, none of these can actually run into this codepath, because
> it is only called on architectures without CONFIG_GENERIC_LOCKBREAK,
> or when CONFIG_DEBUG_LOCK_ALLOC is set without CONFIG_LOCKDEP, and none
> of those combinations are possible on the three architectures.
>
> Going back in the git history, it appears that arch/mn10300 may have
> been able to run into this code path, but there is a good chance that
> it never worked. On the architectures that still exist, it was
> already impossible to hit back in 2008 after the introduction of
> CONFIG_GENERIC_LOCKBREAK, and possibly earlier.
>
> As this is all dead code, just remove it and the helper functions built
> around it. For arch/ia64, the inline asm could be cleaned up, but
> it seems safer to leave it untouched.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Does that mean we can also remove the GENERIC_LOCKBREAK config option 
from the Kconfig files as well?

Cheers,
Longman



  parent reply	other threads:[~2021-10-23  1:38 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-22 11:59 [PATCH] locking: remove spin_lock_flags() etc Arnd Bergmann
2021-10-22 14:10 ` Helge Deller
2021-10-23  1:37 ` Waiman Long [this message]
2021-10-23 16:04   ` Arnd Bergmann
2021-10-25  9:57     ` Peter Zijlstra
2021-10-25 10:06       ` Peter Zijlstra
2021-10-25 13:06       ` Arnd Bergmann
2021-10-25 14:33         ` Peter Zijlstra
2021-10-27 12:01           ` Michael Ellerman
2021-10-25 15:28         ` Waiman Long
2021-10-25 15:44           ` Arnd Bergmann
2021-10-25 18:25             ` Waiman Long

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