From: Al Viro <viro@zeniv.linux.org.uk>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-fsdevel@vger.kernel.org,
Matthew Wilcox <willy@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH 3/4] fs/dcache: Use __d_lookup_unhash() in __d_add/move()
Date: Tue, 26 Jul 2022 04:00:40 +0100 [thread overview]
Message-ID: <Yt9Y2JhqVHOP0vRT@ZenIV> (raw)
In-Reply-To: <20220613140712.77932-4-bigeasy@linutronix.de>
On Mon, Jun 13, 2022 at 04:07:11PM +0200, Sebastian Andrzej Siewior wrote:
> __d_add() and __d_move() invoke __d_lookup_done() from within a preemption
> disabled region. This violates the PREEMPT_RT constraints as the wake up
> acquires wait_queue_head::lock which is a "sleeping" spinlock on RT.
>
> As a preparation for solving this completely, invoke __d_lookup_unhash()
> from __d_add/move() and handle the wakeup there.
>
> This allows to move the spin_lock/unlock(dentry::lock) pair into
> __d_lookup_done() which debloats the d_lookup_done() inline.
It also changes calling conventions for a helper that is, unfortunately,
exported. Sure, nobody outside of fs/dcache.c and d_lookup_done() is
supposed to be using it. But... export is export.
Rename that sucker, please - at least that way whoever's playing with
it will get a build breakage.
next prev parent reply other threads:[~2022-07-26 3:00 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-13 14:07 fs/dcache: Resolve the last RT woes Sebastian Andrzej Siewior
2022-06-13 14:07 ` [PATCH 1/4] fs/dcache: Disable preemption on i_dir_seq write side on PREEMPT_RT Sebastian Andrzej Siewior
2022-06-13 14:07 ` [PATCH 2/4] fs/dcache: Split __d_lookup_done() Sebastian Andrzej Siewior
2022-07-27 3:31 ` Al Viro
2022-07-27 3:36 ` Al Viro
2022-06-13 14:07 ` [PATCH 3/4] fs/dcache: Use __d_lookup_unhash() in __d_add/move() Sebastian Andrzej Siewior
2022-07-26 3:00 ` Al Viro [this message]
2022-07-26 7:47 ` [PATCH 3/4 v2] " Sebastian Andrzej Siewior
2022-06-13 14:07 ` [PATCH 4/4] fs/dcache: Move wakeup out of i_seq_dir write held region Sebastian Andrzej Siewior
2022-07-08 15:52 ` fs/dcache: Resolve the last RT woes Thomas Gleixner
2022-07-25 15:49 ` Sebastian Andrzej Siewior
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