From: Balbir Singh <bsingharora@gmail.com>
To: Keith Busch <kbusch@kernel.org>
Cc: Sagi Grimberg <sagi@grimberg.me>,
James Smart <james.smart@broadcom.com>,
linux-nvme@lists.infradead.org,
Edmund Nadolski <edmund.nadolski@intel.com>,
Judy Brock <judy.brock@samsung.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCHv4 5/5] nvme: Wait for reset state when required
Date: Wed, 16 Oct 2019 11:56:57 +1100 [thread overview]
Message-ID: <20191016005247.GA18485@balbir-desktop> (raw)
In-Reply-To: <20191010165736.12081-6-kbusch@kernel.org>
On Fri, Oct 11, 2019 at 01:57:36AM +0900, Keith Busch wrote:
> Prevent simultaneous controller disabling/enabling tasks from interfering
> with each other through a method to wait until the task successfully
> transitioned the controller to the RESETTING state. This ensures disabling
> the controller will not be interrupted by another reset path, otherwise
> a concurrent reset would leave the controller in the wrong state.
>
Yes, I've run into this when nvme_core.io_timeout is smaller than the
time required to wait on reset (CTS.RDY) and multiple resets occur one
after the other.
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
> drivers/nvme/host/core.c | 41 +++++++++++++++++++++++++++++++++--
> drivers/nvme/host/nvme.h | 4 ++++
> drivers/nvme/host/pci.c | 46 +++++++++++++++++++++++++++-------------
> 3 files changed, 74 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 0f5a82b7d3a4..7442c99a5ed7 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -126,7 +126,7 @@ static void nvme_queue_scan(struct nvme_ctrl *ctrl)
> * code paths that can't be interrupted by other reset attempts. A hot removal
> * may prevent this from succeeding.
> */
> -static int nvme_try_sched_reset(struct nvme_ctrl *ctrl)
> +int nvme_try_sched_reset(struct nvme_ctrl *ctrl)
> {
> if (ctrl->state != NVME_CTRL_RESETTING)
> return -EBUSY;
> @@ -134,6 +134,7 @@ static int nvme_try_sched_reset(struct nvme_ctrl *ctrl)
> return -EBUSY;
> return 0;
> }
> +EXPORT_SYMBOL_GPL(nvme_try_sched_reset);
>
> int nvme_reset_ctrl(struct nvme_ctrl *ctrl)
> {
> @@ -384,8 +385,10 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
> break;
> }
>
> - if (changed)
> + if (changed) {
> ctrl->state = new_state;
> + wake_up_all(&ctrl->state_wq);
> + }
Shouldn't we wake up only if the new_state is terminal or if the
new_state is NVME_CTRL_RESETTING?
>
> spin_unlock_irqrestore(&ctrl->lock, flags);
> if (changed && ctrl->state == NVME_CTRL_LIVE)
> @@ -394,6 +397,39 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
> }
> EXPORT_SYMBOL_GPL(nvme_change_ctrl_state);
>
> +/*
> + * Returns true for sink states that can't ever transition back to live.
> + */
> +static bool nvme_state_terminal(struct nvme_ctrl *ctrl)
> +{
> + switch (ctrl->state) {
> + case NVME_CTRL_NEW:
> + case NVME_CTRL_LIVE:
> + case NVME_CTRL_RESETTING:
> + case NVME_CTRL_CONNECTING:
> + return false;
> + case NVME_CTRL_DELETING:
> + case NVME_CTRL_DEAD:
> + return true;
> + default:
> + WARN_ONCE(1, "Unhandled ctrl state:%d", ctrl->state);
> + return true;
> + }
> +}
> +
> +/*
> + * Waits for the controller state to be resetting, or returns false if it is
> + * not possible to ever transition to that state.
> + */
> +bool nvme_wait_reset(struct nvme_ctrl *ctrl)
> +{
> + wait_event(ctrl->state_wq,
> + nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING) ||
Would we expect this nvme_change_ctrl_state to cause a wake_up_all()
right away?
> + nvme_state_terminal(ctrl));
> + return ctrl->state == NVME_CTRL_RESETTING;
> +}
> +EXPORT_SYMBOL_GPL(nvme_wait_reset);
> +
> static void nvme_free_ns_head(struct kref *ref)
> {
> struct nvme_ns_head *head =
> @@ -3999,6 +4035,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
> INIT_WORK(&ctrl->async_event_work, nvme_async_event_work);
> INIT_WORK(&ctrl->fw_act_work, nvme_fw_act_work);
> INIT_WORK(&ctrl->delete_work, nvme_delete_ctrl_work);
> + init_waitqueue_head(&ctrl->state_wq);
>
> INIT_DELAYED_WORK(&ctrl->ka_work, nvme_keep_alive_work);
> memset(&ctrl->ka_cmd, 0, sizeof(ctrl->ka_cmd));
> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> index 2ba577271ada..22e8401352c2 100644
> --- a/drivers/nvme/host/nvme.h
> +++ b/drivers/nvme/host/nvme.h
> @@ -15,6 +15,7 @@
> #include <linux/sed-opal.h>
> #include <linux/fault-inject.h>
> #include <linux/rcupdate.h>
> +#include <linux/wait.h>
>
> #include <trace/events/block.h>
>
> @@ -198,6 +199,7 @@ struct nvme_ctrl {
> struct cdev cdev;
> struct work_struct reset_work;
> struct work_struct delete_work;
> + wait_queue_head_t state_wq;
>
> struct nvme_subsystem *subsys;
> struct list_head subsys_entry;
> @@ -448,6 +450,7 @@ void nvme_complete_rq(struct request *req);
> bool nvme_cancel_request(struct request *req, void *data, bool reserved);
> bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
> enum nvme_ctrl_state new_state);
> +bool nvme_wait_reset(struct nvme_ctrl *ctrl);
> int nvme_disable_ctrl(struct nvme_ctrl *ctrl);
> int nvme_enable_ctrl(struct nvme_ctrl *ctrl);
> int nvme_shutdown_ctrl(struct nvme_ctrl *ctrl);
> @@ -498,6 +501,7 @@ int nvme_set_queue_count(struct nvme_ctrl *ctrl, int *count);
> void nvme_stop_keep_alive(struct nvme_ctrl *ctrl);
> int nvme_reset_ctrl(struct nvme_ctrl *ctrl);
> int nvme_reset_ctrl_sync(struct nvme_ctrl *ctrl);
> +int nvme_try_sched_reset(struct nvme_ctrl *ctrl);
> int nvme_delete_ctrl(struct nvme_ctrl *ctrl);
>
> int nvme_get_log(struct nvme_ctrl *ctrl, u32 nsid, u8 log_page, u8 lsp,
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index 7d0de87d733d..4fcfd01f350d 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -2463,6 +2463,14 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown)
> mutex_unlock(&dev->shutdown_lock);
> }
>
> +static int nvme_disable_prepare_reset(struct nvme_dev *dev, bool shutdown)
> +{
This sounds like we should disable the prepare reset, but I think it
really means in nvme disable, prepare for reset. Should we call it
nvme_disable_and_prepare_reset()?
I've not checked the state machine by hand, but
Acked-by: Balbir Singh <bsingharora@gmail.com>
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next prev parent reply other threads:[~2019-10-16 0:57 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 16:57 [PATCHv4 0/5] nvme: double reset prevention Keith Busch
2019-10-10 16:57 ` [PATCHv4 1/5] nvme-pci: Free tagset if no IO queues Keith Busch
2019-10-10 16:57 ` [PATCHv4 2/5] nvme: Remove ADMIN_ONLY state Keith Busch
2019-10-10 16:57 ` [PATCHv4 3/5] nvme: Restart request timers in resetting state Keith Busch
2019-10-10 16:57 ` [PATCHv4 4/5] nvme: Prevent resets during paused controller state Keith Busch
2019-10-10 16:57 ` [PATCHv4 5/5] nvme: Wait for reset state when required Keith Busch
2019-10-16 0:56 ` Balbir Singh [this message]
2019-10-10 17:09 ` [PATCHv4 0/5] nvme: double reset prevention Nadolski, Edmund
2019-10-11 15:58 ` Nadolski, Edmund
2019-10-11 16:27 ` Keith Busch
2019-10-14 7:15 ` Christoph Hellwig
2019-10-14 15:06 ` Keith Busch
2019-10-14 7:14 ` Christoph Hellwig
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