From: Sagi Grimberg <sagig@dev.mellanox.co.il>
To: Keith Busch <keith.busch@intel.com>
Cc: Wenbo Wang <wenbo.wang@memblaze.com>, Jens Axboe <axboe@fb.com>,
Wenbo Wang <mail_weber_wang@163.com>,
"Wenwei.Tao" <wenwei.tao@memblaze.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
Subject: Re: [PATCH] NVMe: do not touch sq door bell if nvmeq has been suspended
Date: Tue, 2 Feb 2016 19:20:01 +0200 [thread overview]
Message-ID: <56B0E541.1000907@dev.mellanox.co.il> (raw)
In-Reply-To: <20160202144648.GA10728@localhost.localdomain>
> We free the transfer buffers when a command is cancelled. The controller,
> however, may still own the command and may try to write to them. We
> have to fence the controller off from being able to do that, so we can't
> cancel inflight commands while the PCI device is still bus master enabled.
>
> In a perfect world, we could trust in disabling with NVMe registers,
> but sometimes we can't rely on that.
OK, I wasn't aware that we cannot rely on that.
So it looks like we cannot change the ordering. So this leaves us with
the need to guarantee that no queue_rq is inflight before we unmap.
WARNING: multiple messages have this Message-ID (diff)
From: sagig@dev.mellanox.co.il (Sagi Grimberg)
Subject: [PATCH] NVMe: do not touch sq door bell if nvmeq has been suspended
Date: Tue, 2 Feb 2016 19:20:01 +0200 [thread overview]
Message-ID: <56B0E541.1000907@dev.mellanox.co.il> (raw)
In-Reply-To: <20160202144648.GA10728@localhost.localdomain>
> We free the transfer buffers when a command is cancelled. The controller,
> however, may still own the command and may try to write to them. We
> have to fence the controller off from being able to do that, so we can't
> cancel inflight commands while the PCI device is still bus master enabled.
>
> In a perfect world, we could trust in disabling with NVMe registers,
> but sometimes we can't rely on that.
OK, I wasn't aware that we cannot rely on that.
So it looks like we cannot change the ordering. So this leaves us with
the need to guarantee that no queue_rq is inflight before we unmap.
next prev parent reply other threads:[~2016-02-02 17:20 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-01 15:42 [PATCH] NVMe: do not touch sq door bell if nvmeq has been suspended Wenbo Wang
2016-02-01 15:42 ` Wenbo Wang
2016-02-01 15:59 ` Busch, Keith
2016-02-01 15:59 ` Busch, Keith
2016-02-01 16:17 ` Wenbo Wang
2016-02-01 16:17 ` Wenbo Wang
2016-02-01 16:54 ` Jens Axboe
2016-02-01 16:54 ` Jens Axboe
2016-02-02 7:15 ` Wenbo Wang
2016-02-02 12:41 ` Sagi Grimberg
2016-02-02 12:41 ` Sagi Grimberg
2016-02-02 14:27 ` Keith Busch
2016-02-02 14:27 ` Keith Busch
2016-02-02 14:33 ` Sagi Grimberg
2016-02-02 14:33 ` Sagi Grimberg
2016-02-02 14:46 ` Keith Busch
2016-02-02 14:46 ` Keith Busch
2016-02-02 17:20 ` Sagi Grimberg [this message]
2016-02-02 17:20 ` Sagi Grimberg
2016-02-03 0:49 ` Wenbo Wang
2016-02-02 17:25 ` Keith Busch
2016-02-02 17:25 ` Keith Busch
2016-02-03 0:19 ` Wenbo Wang
2016-02-03 14:41 ` Keith Busch
2016-02-03 14:41 ` Keith Busch
2016-02-03 16:35 ` Wenbo Wang
2016-02-03 16:38 ` Keith Busch
2016-02-03 16:38 ` Keith Busch
2016-02-06 14:32 ` Wenbo Wang
2016-02-07 13:41 ` Sagi Grimberg
2016-02-07 13:41 ` Sagi Grimberg
2016-02-08 15:01 ` Keith Busch
2016-02-08 15:01 ` Keith Busch
2016-02-09 11:22 ` Wenbo Wang
2016-02-09 22:55 ` Keith Busch
2016-02-09 22:55 ` Keith Busch
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