[PATCH AUTOSEL 4.19 43/59] nvme: Prevent resets during paused controller state

Sasha Levin
2019-10-26T13:29:12Z

From: Keith Busch <kbusch@kernel.org>

[ Upstream commit 4c75f877853cfa81b12374a07208e07b077f39b8 ]

A paused controller is doing critical internal activation work in the
background. Prevent subsequent controller resets from occurring during
this period by setting the controller state to RESETTING first. A helper
function, nvme_try_sched_reset_work(), is introduced for these paths so
they may continue with scheduling the reset_work after they've completed
their uninterruptible critical section.

Tested-by: Edmund Nadolski <edmund.nadolski@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/nvme/host/core.c | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index ddd5c72a565ad..95d4f1a6dd795 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -126,6 +126,21 @@ static void nvme_queue_scan(struct nvme_ctrl *ctrl)
queue_work(nvme_wq, &ctrl->scan_work);
}

+/*
+ * Use this function to proceed with scheduling reset_work for a controller
+ * that had previously been set to the resetting state. This is intended for
+ * 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)
+{
+ if (ctrl->state != NVME_CTRL_RESETTING)
+ return -EBUSY;
+ if (!queue_work(nvme_reset_wq, &ctrl->reset_work))
+ return -EBUSY;
+ return 0;
+}
+
int nvme_reset_ctrl(struct nvme_ctrl *ctrl)
{
if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
@@ -3445,13 +3460,13 @@ static void nvme_fw_act_work(struct work_struct *work)
if (time_after(jiffies, fw_act_timeout)) {
dev_warn(ctrl->device,
"Fw activation timeout, reset controller\n");
- nvme_reset_ctrl(ctrl);
- break;
+ nvme_try_sched_reset(ctrl);
+ return;
}
msleep(100);
}

- if (ctrl->state != NVME_CTRL_LIVE)
+ if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_LIVE))
return;

nvme_start_queues(ctrl);
@@ -3467,7 +3482,13 @@ static void nvme_handle_aen_notice(struct nvme_ctrl *ctrl, u32 result)
nvme_queue_scan(ctrl);
break;
case NVME_AER_NOTICE_FW_ACT_STARTING:
- queue_work(nvme_wq, &ctrl->fw_act_work);
+ /*
+ * We are (ab)using the RESETTING state to prevent subsequent
+ * recovery actions from interfering with the controller's
+ * firmware activation.
+ */
+ if (nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING))
+ queue_work(nvme_wq, &ctrl->fw_act_work);
break;
#ifdef CONFIG_NVME_MULTIPATH
case NVME_AER_NOTICE_ANA:
--
2.20.1