linux-kernel - Re: [PATCH 34/33] netfs: Use in_interrupt() not in

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Message-ID: <20210216090626.kqnk726i6f77libt@linutronix.de>
Date:   Tue, 16 Feb 2021 10:06:26 +0100
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Christoph Hellwig <hch@....de>
Cc:     David Howells <dhowells@...hat.com>,
        Trond Myklebust <trondmy@...merspace.com>,
        Marc Dionne <marc.dionne@...istor.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        Steve French <sfrench@...ba.org>,
        Dominique Martinet <asmadeus@...ewreck.org>,
        linux-cifs@...r.kernel.org, ceph-devel@...r.kernel.org,
        Jeff Layton <jlayton@...hat.com>,
        Matthew Wilcox <willy@...radead.org>, linux-cachefs@...hat.com,
        Alexander Viro <viro@...iv.linux.org.uk>, linux-mm@...ck.org,
        linux-afs@...ts.infradead.org,
        v9fs-developer@...ts.sourceforge.net,
        linux-fsdevel@...r.kernel.org, linux-nfs@...r.kernel.org,
        Jeff Layton <jlayton@...nel.org>,
        David Wysochanski <dwysocha@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 34/33] netfs: Use in_interrupt() not in_softirq()

On 2021-02-16 09:42:30 [+0100], Christoph Hellwig wrote:
> On Mon, Feb 15, 2021 at 10:46:23PM +0000, David Howells wrote:
> > The in_softirq() in netfs_rreq_terminated() works fine for the cache being
> > on a normal disk, as the completion handlers may get called in softirq
> > context, but for an NVMe drive, the completion handler may get called in
> > IRQ context.
> > 
> > Fix to use in_interrupt() instead of in_softirq() throughout the read
> > helpers, particularly when deciding whether to punt code that might sleep
> > off to a worker thread.
> 
> We must not use either check, as they all are unreliable especially
> for PREEMPT-RT.

Yes, please. I try to cleanup the users one by one
    https://lore.kernel.org/r/20200914204209.256266093@linutronix.de/
    https://lore.kernel.org/amd-gfx/20210209124439.408140-1-bigeasy@linutronix.de/

Sebastian