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[142.68.57.212]) by smtp.gmail.com with ESMTPSA id f21sm17199382qtc.97.2020.04.07.04.51.15 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 07 Apr 2020 04:51:15 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jLml9-0007SR-15; Tue, 07 Apr 2020 08:51:15 -0300 Date: Tue, 7 Apr 2020 08:51:15 -0300 From: Jason Gunthorpe To: Leon Romanovsky Cc: linux-rdma@vger.kernel.org Subject: Re: [PATCH] RDMA/uverbs: Make the event_queue fds return POLLERR when disassociated Message-ID: <20200407115115.GT20941@ziepe.ca> References: <0-v1-ace813388969+48859-uverbs_poll_fix%jgg@mellanox.com> <20200407051632.GL80989@unreal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200407051632.GL80989@unreal> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Apr 07, 2020 at 08:16:32AM +0300, Leon Romanovsky wrote: > On Mon, Apr 06, 2020 at 09:44:26PM -0300, Jason Gunthorpe wrote: > > From: Jason Gunthorpe > > > > If is_closed is set, and the event list is empty, then read() will return > > -EIO without blocking. After setting is_closed in > > ib_uverbs_free_event_queue(), we do trigger a wake_up on the poll_wait, > > but the fops->poll() function does not check it, so poll will continue to > > sleep on an empty list. > > > > Fixes: 14e23bd6d221 ("RDMA/core: Fix locking in ib_uverbs_event_read") > > Signed-off-by: Jason Gunthorpe > > drivers/infiniband/core/uverbs_main.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c > > index 2d4083bf4a0487..8710a3427146e7 100644 > > +++ b/drivers/infiniband/core/uverbs_main.c > > @@ -296,6 +296,8 @@ static __poll_t ib_uverbs_event_poll(struct ib_uverbs_event_queue *ev_queue, > > spin_lock_irq(&ev_queue->lock); > > if (!list_empty(&ev_queue->event_list)) > > pollflags = EPOLLIN | EPOLLRDNORM; > > + else if (ev_queue->is_closed) > > + pollflags = EPOLLERR; > > spin_unlock_irq(&ev_queue->lock); > > Don't you need to set EPOLLHUP too? Probably, it won't change anything, > just for the sake of the correctness. HUP means read will return 0, in this case read returns -EIO Jason