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Message-ID: <2c062c31-ec3d-9d4a-8f5c-0ba6f623dfa4@oracle.com>
Date: Mon, 15 Jan 2018 10:02:04 +0800
From: "jianchao.wang" <jianchao.w.wang@...cle.com>
To: Sagi Grimberg <sagi@...mberg.me>, keith.busch@...el.com,
axboe@...com, hch@....de
Cc: linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 1/2] nvme: split resetting state into reset_prepate and
resetting
Hi keith
Thanks for your kindly review and response.
On 01/14/2018 05:48 PM, Sagi Grimberg wrote:
>
>> Currently, the ctrl->state will be changed to NVME_CTRL_RESETTING
>> before queue the reset work. This is not so strict. There could be
>> a big gap before the reset_work callback is invoked. In addition,
>> there is some disable work in the reset_work callback, strictly
>> speaking, not part of reset work, and could lead to some confusion.
>>
>> This patch splits the NVME_CTRL_RESETTING into NVME_CTRL_RESET_PREPARE
>> and NVME_CTRL_RESETTING. Before queue the reset work, changes state
>> to NVME_CTRL_RESET_PREPARE, after disable work completes, changes
>> state to NVME_CTRL_RESETTING.
>
> What guarantees that nvme_timeout will do the right thing? If it
> is relying on the fact that nvme-pci sets the state to RESETTING
> only _after_ quiescing the requests queues it needs to be documented
> as its a real delicate dependency.
nvme_dev_disable will iterate all the outstanding request with nvme_cancel_request to requeue
the IO requests and complete admin requests. This is the boundary.
Transit the state from RESET_PREPARE to RESETTING after nmve_dev_disable.
So when the state is RESETTING, all the previous outstanding requests all has been handled by
nvme_cancel_request, the only requests can expire at this moment is from the adminq of initializing
procedure.
>
>
>
>>
>> Suggested-by: Christoph Hellwig <hch@....de>
>> Signed-off-by: Jianchao Wang <jianchao.w.wang@...cle.com>
>> ---
>> drivers/nvme/host/core.c | 17 +++++++++++++++--
>> drivers/nvme/host/fc.c | 2 ++
>> drivers/nvme/host/nvme.h | 1 +
>> drivers/nvme/host/pci.c | 28 ++++++++++++++++++++++------
>> drivers/nvme/host/rdma.c | 8 ++++++++
>> drivers/nvme/target/loop.c | 5 +++++
>> 6 files changed, 53 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>> index 1e46e60..106a437 100644
>> --- a/drivers/nvme/host/core.c
>> +++ b/drivers/nvme/host/core.c
>> @@ -87,7 +87,7 @@ static __le32 nvme_get_log_dw10(u8 lid, size_t size)
>> int nvme_reset_ctrl(struct nvme_ctrl *ctrl)
>> {
>> - if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
>> + if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESET_PREPARE))
>> return -EBUSY;
>> if (!queue_work(nvme_wq, &ctrl->reset_work))
>> return -EBUSY;
>> @@ -243,7 +243,7 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
>> break;
>> }
>> break;
>> - case NVME_CTRL_RESETTING:
>> + case NVME_CTRL_RESET_PREPARE:
>> switch (old_state) {
>> case NVME_CTRL_NEW:
>> case NVME_CTRL_LIVE:
>> @@ -253,10 +253,21 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
>> break;
>> }
>> break;
>> +
>> + case NVME_CTRL_RESETTING:
>> + switch (old_state) {
>> + case NVME_CTRL_RESET_PREPARE:
>> + changed = true;
>> + /* FALLTHRU */
>> + default:
>> + break;
>> + }
>> + break;
>> case NVME_CTRL_RECONNECTING:
>> switch (old_state) {
>> case NVME_CTRL_LIVE:
>> case NVME_CTRL_RESETTING:
>> + case NVME_CTRL_RESET_PREPARE:
>> changed = true;
>> /* FALLTHRU */
>> default:
>> @@ -267,6 +278,7 @@ bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
>> switch (old_state) {
>> case NVME_CTRL_LIVE:
>> case NVME_CTRL_RESETTING:
>> + case NVME_CTRL_RESET_PREPARE:
>> case NVME_CTRL_RECONNECTING:
>> changed = true;
>> /* FALLTHRU */
>> @@ -2603,6 +2615,7 @@ static ssize_t nvme_sysfs_show_state(struct device *dev,
>> [NVME_CTRL_NEW] = "new",
>> [NVME_CTRL_LIVE] = "live",
>> [NVME_CTRL_RESETTING] = "resetting",
>> + [NVME_CTRL_RESET_PREPARE] = "reset-prepare",
>> [NVME_CTRL_RECONNECTING]= "reconnecting",
>> [NVME_CTRL_DELETING] = "deleting",
>> [NVME_CTRL_DEAD] = "dead",
>> diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
>> index 794e66e..516c1ea 100644
>> --- a/drivers/nvme/host/fc.c
>> +++ b/drivers/nvme/host/fc.c
>> @@ -547,6 +547,7 @@ nvme_fc_resume_controller(struct nvme_fc_ctrl *ctrl)
>> break;
>> case NVME_CTRL_RESETTING:
>> + case NVME_CTRL_RESET_PREPARE:
>> /*
>> * Controller is already in the process of terminating the
>> * association. No need to do anything further. The reconnect
>> @@ -790,6 +791,7 @@ nvme_fc_ctrl_connectivity_loss(struct nvme_fc_ctrl *ctrl)
>> break;
>> case NVME_CTRL_RESETTING:
>> + case NVME_CTRL_RESET_PREPARE:
>> /*
>> * Controller is already in the process of terminating the
>> * association. No need to do anything further. The reconnect
>
> James, can you take a look at this?
>
>> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
>> index f5800c3..e477c35 100644
>> --- a/drivers/nvme/host/pci.c
>> +++ b/drivers/nvme/host/pci.c
>> @@ -1141,8 +1141,13 @@ static bool nvme_should_reset(struct nvme_dev *dev, u32 csts)
>> bool nssro = dev->subsystem && (csts & NVME_CSTS_NSSRO);
>> /* If there is a reset ongoing, we shouldn't reset again. */
>> - if (dev->ctrl.state == NVME_CTRL_RESETTING)
>> + switch (dev->ctrl.state) {
>> + case NVME_CTRL_RESETTING:
>> + case NVME_CTRL_RESET_PREPARE:
>> return false;
>> + default:
>> + break;
>> + }
>
> Isn't the indentation off? also in other places...
I see all the "switch" in core.c and pci.c is this style.
switch(x) {
case xxx:
...
case xxx:
...
}
So I followed.... :)
>
>> @@ -2292,7 +2303,7 @@ static void nvme_reset_work(struct work_struct *work)
>> bool was_suspend = !!(dev->ctrl.ctrl_config & NVME_CC_SHN_NORMAL);
>> int result = -ENODEV;
>> - if (WARN_ON(dev->ctrl.state != NVME_CTRL_RESETTING))
>> + if (WARN_ON(dev->ctrl.state != NVME_CTRL_RESET_PREPARE))
>> goto out;
>> /*
>> @@ -2302,6 +2313,11 @@ static void nvme_reset_work(struct work_struct *work)
>> if (dev->ctrl.ctrl_config & NVME_CC_ENABLE)
>> nvme_dev_disable(dev, false);
>> + if (!nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING)) {
>> + WARN_ON_ONCE(dev->ctrl.state != NVME_CTRL_DELETING);
>> + goto out;
>> + }
>> +
>
> This needs documentation on _why_ here.
OK, sure.
>
>> - nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESETTING);
>> + nvme_change_ctrl_state(&dev->ctrl, NVME_CTRL_RESET_PREPARE);
>> dev_info(dev->ctrl.device, "pci function %s\n", dev_name(&pdev->dev));
>
> Can you rebase on top of my commit:
> 4caff8fc19f1 nvme-pci: don't open-code nvme_reset_ctrl
OK, I will
>
>> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
>> index 37af565..8ae073e 100644
>> --- a/drivers/nvme/host/rdma.c
>> +++ b/drivers/nvme/host/rdma.c
>> @@ -1753,6 +1753,14 @@ static void nvme_rdma_reset_ctrl_work(struct work_struct *work)
>> nvme_stop_ctrl(&ctrl->ctrl);
>> nvme_rdma_shutdown_ctrl(ctrl, false);
>> + changed = nvme_change_ctrl_state(&ctrl->ctrl,
>> + NVME_CTRL_RESET_PREPARE);
>> + if (!changed) {
>> + /* state change failure is ok if we're in DELETING state */
>> + WARN_ON_ONCE(ctrl->ctrl.state != NVME_CTRL_DELETING);
>> + return;
>> + }
>> +
>
> setting RESET_PREPARE here??
This is my fault. I checked the code time by time, but still a stupid fault here.
>
> Also, the error recovery code is mutually excluded from reset_work
> by trying to set the same state which is protected by the ctrl state
> machine, so a similar change is needed there.
>
> So in order not to break rdma ctrl reset (again) please look at:
> bcdacf7fc3d8 nvme-rdma: fix concurrent reset and reconnect
>
Ok, I will look into it.
Thanks for your directive. That's really appreciated.
Thanks
Jianchao
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