From: Al Viro <viro@ZenIV.linux.org.uk>
To: Christoph Hellwig <hch@lst.de>
Cc: Avi Kivity <avi@scylladb.com>,
linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
netdev@vger.kernel.org, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 06/28] aio: implement IOCB_CMD_POLL
Date: Thu, 22 Mar 2018 16:52:55 +0000 [thread overview]
Message-ID: <20180322165255.GI30522@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20180321074032.14211-7-hch@lst.de>
On Wed, Mar 21, 2018 at 08:40:10AM +0100, Christoph Hellwig wrote:
> Simple one-shot poll through the io_submit() interface. To poll for
> a file descriptor the application should submit an iocb of type
> IOCB_CMD_POLL. It will poll the fd for the events specified in the
> the first 32 bits of the aio_buf field of the iocb.
>
> Unlike poll or epoll without EPOLLONESHOT this interface always works
> in one shot mode, that is once the iocb is completed, it will have to be
> resubmitted.
AFAICS, your wakeup can race with io_cancel(), leading to double fput().
You are checking the "somebody had committed itself to cancelling that
thing" bit outside of ->ctx_lock on the wakeup side, and I don't see
anything to prevent both getting to __aio_poll_complete() on the same
iocb, with obvious results.
I might be missing something subtle in there, but then it would be nice to
have it covered in commit message...
next prev parent reply other threads:[~2018-03-22 16:52 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-21 7:40 aio poll and a new in-kernel poll API V6 Christoph Hellwig
2018-03-21 7:40 ` [PATCH 01/28] fs: unexport poll_schedule_timeout Christoph Hellwig
2018-03-21 9:05 ` Greg KH
2018-03-21 7:40 ` [PATCH 02/28] fs: cleanup do_pollfd Christoph Hellwig
2018-03-21 9:06 ` Greg KH
2018-03-21 7:40 ` [PATCH 03/28] fs: update documentation to mention __poll_t Christoph Hellwig
2018-03-21 9:06 ` Greg KH
2018-03-21 16:28 ` Darrick J. Wong
2018-03-21 7:40 ` [PATCH 04/28] fs: add new vfs_poll and file_can_poll helpers Christoph Hellwig
2018-03-21 9:07 ` Greg KH
2018-03-21 7:40 ` [PATCH 05/28] fs: introduce new ->get_poll_head and ->poll_mask methods Christoph Hellwig
2018-03-21 9:08 ` Greg KH
2018-03-21 16:29 ` Darrick J. Wong
2018-03-21 7:40 ` [PATCH 06/28] aio: implement IOCB_CMD_POLL Christoph Hellwig
2018-03-21 9:09 ` Greg KH
2018-03-21 16:31 ` Darrick J. Wong
2018-03-22 16:52 ` Al Viro [this message]
2018-03-22 17:24 ` Christoph Hellwig
2018-03-22 18:16 ` Al Viro
2018-03-23 18:05 ` Christoph Hellwig
2018-03-21 7:40 ` [PATCH 07/28] net: refactor socket_poll Christoph Hellwig
2018-03-21 7:40 ` [PATCH 08/28] net: add support for ->poll_mask in proto_ops Christoph Hellwig
2018-03-21 7:40 ` [PATCH 09/28] net: remove sock_no_poll Christoph Hellwig
2018-03-21 7:40 ` [PATCH 10/28] net/tcp: convert to ->poll_mask Christoph Hellwig
2018-03-21 7:40 ` [PATCH 11/28] net/unix: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 12/28] net: convert datagram_poll users tp ->poll_mask Christoph Hellwig
2018-03-21 9:11 ` Greg KH
2018-03-21 7:40 ` [PATCH 13/28] net/dccp: convert to ->poll_mask Christoph Hellwig
2018-03-21 7:40 ` [PATCH 14/28] net/atm: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 15/28] net/vmw_vsock: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 16/28] net/tipc: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 17/28] net/sctp: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 18/28] net/bluetooth: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 19/28] net/caif: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 20/28] net/nfc: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 21/28] net/phonet: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 22/28] net/iucv: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 23/28] net/rxrpc: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 24/28] crypto: af_alg: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 25/28] pipe: " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 26/28] eventfd: switch " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 27/28] timerfd: convert " Christoph Hellwig
2018-03-21 7:40 ` [PATCH 28/28] random: " Christoph Hellwig
2018-03-21 9:10 ` Greg KH
2018-03-22 13:49 ` Theodore Y. Ts'o
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