Re: [PATCH V3 1/2] nvme: split resetting state into reset_prepate and resetting
From: Sagi Grimberg
Date: Sun Jan 14 2018 - 04:48:56 EST
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.
Suggested-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
---
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...
@@ -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.
- 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
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??
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