From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 499D71E896 for ; Mon, 18 Mar 2024 14:40:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710772804; cv=none; b=a0Ry1h7IA5q4WOHJ+icjLO4NfwyziU+6Dh83d5SHm3NCNJjuHh87rNi0XbJRFDc4i1ch8O5mfPfaFRyLFe9P9v1B/+w8GGgnB4nCsW+BGvJiAf8I0xyxaCeUKCdTZQm6ZUxcHKabqQEaW7vZPfSMfddanQBvfKHteaWt6O7+W5I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710772804; c=relaxed/simple; bh=mDb4fKjuX1xZ4RuUReBdzrB45DUXByBKBIZZ+nG/0t8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UXoXtxEqNsXpRLPjria0UiyF+ybH9ofsV39b9QN/0sIGp8RZnqgR4vlbuJ0ykSvwgrWT+6RNtnB74PEjXhI8mAB0CgriO2MJIYAxnvg/0BnG4FYF/O1IObSVPl7OeroiUvM2Rf5t2Xp9JwzJPYvTTmhh9LFb2s5LAipYrRNGSUg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=TZyT7g84; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TZyT7g84" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1710772802; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gA+MIz9ZKVSW6ey9YkrgV5BYJeuSIfMh0t2b+VLIzPs=; b=TZyT7g84mM7Dk6RpGF2rw0GIdTIPirjjvCGxiGUCXigLlim1B9au+7oGMC8bnv4yAcb535 PsG69Ugen+I4MteIMmwv+545E8yNzkQENGw2btBx6Yov8zRskvRZu2UxYICTZtpIBEb252 wEmmXiwPKTMF+oDvKM1yUm9Do8rAs3U= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-626-3Ae3EurMMreViBA-jFmHAw-1; Mon, 18 Mar 2024 10:39:59 -0400 X-MC-Unique: 3Ae3EurMMreViBA-jFmHAw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 863E529AC036; Mon, 18 Mar 2024 14:39:58 +0000 (UTC) Received: from fedora (unknown [10.72.116.15]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 075103C22; Mon, 18 Mar 2024 14:39:54 +0000 (UTC) Date: Mon, 18 Mar 2024 22:39:30 +0800 From: Ming Lei To: Pavel Begunkov Cc: io-uring@vger.kernel.org, linux-block@vger.kernel.org, Jens Axboe , Kanchan Joshi Subject: Re: [PATCH v2 05/14] ublk: don't hard code IO_URING_F_UNLOCKED Message-ID: References: <61b29658-e6a9-449f-a850-1881af1ecbee@gmail.com> <2095ac3e-5e5f-4ea2-a906-a924a25c121a@gmail.com> <8bf6d549-cf66-4412-bebd-fd6e98166552@gmail.com> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <8bf6d549-cf66-4412-bebd-fd6e98166552@gmail.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 On Mon, Mar 18, 2024 at 02:32:16PM +0000, Pavel Begunkov wrote: > On 3/18/24 13:37, Pavel Begunkov wrote: > > On 3/18/24 12:52, Pavel Begunkov wrote: > > > On 3/18/24 08:16, Ming Lei wrote: > > > > On Mon, Mar 18, 2024 at 12:41:50AM +0000, Pavel Begunkov wrote: > > > > > uring_cmd implementations should not try to guess issue_flags, just use > > > > > a newly added io_uring_cmd_complete(). We're loosing an optimisation in > > > > > the cancellation path in ublk_uring_cmd_cancel_fn(), but the assumption > > > > > is that we don't care that much about it. > > > > > > > > > > Signed-off-by: Pavel Begunkov > > > > > Link: https://lore.kernel.org/r/2f7bc9fbc98b11412d10b8fd88e58e35614e3147.1710514702.git.asml.silence@gmail.com > > > > > Signed-off-by: Jens Axboe > > > > > --- > > > > >   drivers/block/ublk_drv.c | 18 ++++++++---------- > > > > >   1 file changed, 8 insertions(+), 10 deletions(-) > > > > > > > > > > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c > > > > > index bea3d5cf8a83..97dceecadab2 100644 > > > > > --- a/drivers/block/ublk_drv.c > > > > > +++ b/drivers/block/ublk_drv.c > > > > > @@ -1417,8 +1417,7 @@ static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq) > > > > >       return true; > > > > >   } > > > > > -static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > > > > > -        unsigned int issue_flags) > > > > > +static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io) > > > > >   { > > > > >       bool done; > > > > > @@ -1432,15 +1431,14 @@ static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io, > > > > >       spin_unlock(&ubq->cancel_lock); > > > > >       if (!done) > > > > > -        io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags); > > > > > +        io_uring_cmd_complete(io->cmd, UBLK_IO_RES_ABORT, 0); > > > > >   } > > > > >   /* > > > > >    * The ublk char device won't be closed when calling cancel fn, so both > > > > >    * ublk device and queue are guaranteed to be live > > > > >    */ > > > > > -static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > > > > > -        unsigned int issue_flags) > > > > > +static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd) > > > > >   { > > > > >       struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd); > > > > >       struct ublk_queue *ubq = pdu->ubq; > > > > > @@ -1464,7 +1462,7 @@ static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd, > > > > >       io = &ubq->ios[pdu->tag]; > > > > >       WARN_ON_ONCE(io->cmd != cmd); > > > > > -    ublk_cancel_cmd(ubq, io, issue_flags); > > > > > +    ublk_cancel_cmd(ubq, io); > > > > > > > > .cancel_fn is always called with .uring_lock held, so this 'issue_flags' can't > > > > be removed, otherwise double task run is caused because .cancel_fn > > > > can be called multiple times if the request stays in ctx->cancelable_uring_cmd. > > > > > > I see, that's exactly why I was asking whether it can be deferred > > > to tw. Let me see if I can get by without that patch, but honestly > > > it's a horrible abuse of the ring state. Any ideas how that can be > > > cleaned up? > > > > I assume io_uring_try_cancel_uring_cmd() can run in parallel with > > completions, so there can be two parallel calls calls to ->uring_cmd > > (e.g. io-wq + cancel), which gives me shivers. Also, I'd rather > > no cancel in place requests of another task, io_submit_flush_completions() > > but it complicates things. > > I'm wrong though on flush_completions, the task there cancels only > its own requests > > io_uring_try_cancel_uring_cmd() { > ... > if (!cancel_all && req->task != task) > continue; > } > > > > Is there any argument against removing requests from the cancellation > > list in io_uring_try_cancel_uring_cmd() before calling ->uring_cmd? > > > > io_uring_try_cancel_uring_cmd() { > >     lock(); > >     for_each_req() { > >         remove_req_from_cancel_list(req); > >         req->file->uring_cmd(); > >     } > >     unlock(); Also the req may not be ready to cancel in ->uring_cmd(), so it should be allowed to retry in future if it isn't canceled this time. Thanks, Ming