From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 6/6] fs: replace f_ops->get_poll_head with a static
        ->f_poll_head pointer
Date: Fri, 29 Jun 2018 15:29:24 +0200
Message-ID: <20180629132924.GB28510@lst.de>
References: <20180628142059.10017-1-hch@lst.de> <20180628142059.10017-7-hch@lst.de> <CA+55aFxy=GFVumxzOqv0LH9kr5aV10yccVUpFWGY3BX2pTsVHw@mail.gmail.com> <20180628181727.GH30522@ZenIV.linux.org.uk> <CA+55aFyPUpd3tWVqbTVXGKjMb42+g-9MCfvjXLpb0RGSOW8sbA@mail.gmail.com> <20180628202837.GI30522@ZenIV.linux.org.uk> <CA+55aFxfkD9ozw77j-bshReLJN4dN2GEdW+R-LkxztceCW6OTg@mail.gmail.com> <20180628213027.GK30522@ZenIV.linux.org.uk>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Christoph Hellwig <hch@lst.de>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>, LKP <lkp@01.org>
To: Al Viro <viro@ZenIV.linux.org.uk>
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On Thu, Jun 28, 2018 at 10:30:27PM +0100, Al Viro wrote:
> > Because I think that what it can do is simply to do the ->poll() calls
> > outside the iocb locks, and then just attach the poll table to the
> > kioctx afterwards.
> 
> I'd do a bit more - embed the first poll_table_entry into poll iocb itself,
> so that the instances that use only one queue wouldn't need any allocations
> at all.

No need for poll_table_entry, we just need a wait_queue_head.
poll_table_entry is an select.c internal (except for two nasty driver) -
neither epoll nor most in-kernel callers use it.