From: Pavel Machek <pavel@denx.de>
To: Sasha Levin <sashal@kernel.org>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Oleg.Karfich@wago.com, Thomas Gleixner <tglx@linutronix.de>,
Al Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH AUTOSEL 4.19 14/14] fs/dcache: Disable preemption on i_dir_seq write side on PREEMPT_RT
Date: Sat, 13 Aug 2022 15:43:34 +0200 [thread overview]
Message-ID: <20220813134334.GA24517@duo.ucw.cz> (raw)
In-Reply-To: <20220811160948.1542842-14-sashal@kernel.org>
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Hi!
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>
> [ Upstream commit cf634d540a29018e8d69ab1befb7e08182bc6594 ]
>
> i_dir_seq is a sequence counter with a lock which is represented by the
> lowest bit. The writer atomically updates the counter which ensures that it
> can be modified by only one writer at a time. This requires preemption to
> be disabled across the write side critical section.
>
> On !PREEMPT_RT kernels this is implicit by the caller acquiring
> dentry::lock. On PREEMPT_RT kernels spin_lock() does not disable preemption
This should not be applied to 4.19 as CONFIG_PREEMPT_RT does not exist
there.
Best regards,
Pavel
--
'DENX Software Engineering GmbH, Managing Director: Wolfgang Denk'
'HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany'
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prev parent reply other threads:[~2022-08-13 13:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20220811160948.1542842-1-sashal@kernel.org>
2022-08-11 16:09 ` [PATCH AUTOSEL 4.19 13/14] d_add_ci(): make sure we don't miss d_lookup_done() Sasha Levin
2022-08-11 16:09 ` [PATCH AUTOSEL 4.19 14/14] fs/dcache: Disable preemption on i_dir_seq write side on PREEMPT_RT Sasha Levin
2022-08-13 13:43 ` Pavel Machek [this message]
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