From: keith.busch@intel.com (Keith Busch)
Subject: [PATCH] nvme-pci: use NOWAIT flag for nvme_set_host_mem
Date: Mon, 29 Jan 2018 13:17:16 -0700 [thread overview]
Message-ID: <20180129201716.GB25515@localhost.localdomain> (raw)
In-Reply-To: <1b7d3700-945f-9272-b6aa-d2ebeaf0cb1e@grimberg.me>
On Mon, Jan 29, 2018@09:55:41PM +0200, Sagi Grimberg wrote:
> > Thanks for the fix. It looks like we still have a problem, though.
> > Commands submitted with the "shutdown_lock" held need to be able to make
> > forward progress without relying on a completion, but this one could
> > block indefinitely.
>
> Can you explain to me why is the shutdown_lock needed to synchronize
> nvme_dev_disable? More concretely, how is nvme_dev_disable different
> from other places where we rely on the ctrl state to serialize stuff?
>
> The only reason I see would be to protect against completion-after-abort
> scenario but I think the block layer should protect against it (checks
> if the request timeout timer fired).
We can probably find a way to use the state machine for this. Disabling
the controller pre-dates the state machine, and the mutex is there to
protect against two actors shutting the controller down at the same
time, like a hot removal at the same time as a timeout handling reset.
next prev parent reply other threads:[~2018-01-29 20:17 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-29 3:07 [PATCH] nvme-pci: use NOWAIT flag for nvme_set_host_mem Jianchao Wang
2018-01-29 8:06 ` jianchao.wang
2018-01-29 16:01 ` Keith Busch
2018-01-29 19:55 ` Sagi Grimberg
2018-01-29 20:17 ` Keith Busch [this message]
2018-01-30 3:41 ` jianchao.wang
2018-01-30 16:13 ` Keith Busch
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