* [PATCH 1/2] nvme: sanitize KATO setting
2021-04-16 11:46 [PATCHv4 0/2] nvme: sanitize KATO setting Hannes Reinecke
@ 2021-04-16 11:46 ` Hannes Reinecke
2021-04-16 11:46 ` [PATCH 2/2] nvme: add 'kato' sysfs attribute Hannes Reinecke
2021-04-20 8:07 ` [PATCHv4 0/2] nvme: sanitize KATO setting Christoph Hellwig
2 siblings, 0 replies; 4+ messages in thread
From: Hannes Reinecke @ 2021-04-16 11:46 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: Sagi Grimberg, Keith Busch, linux-nvme, Hannes Reinecke
According to the NVMe base spec the KATO commands should be sent
at half of the KATO interval, to properly account for round-trip
times.
As we now will only ever send one KATO command per connection we
can easily use the recommended values.
This also fixes a potential issue where the request timeout for
the KATO command does not match the value in the connect command,
which might be causing spurious connection drops from the target.
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/nvme/host/core.c | 18 +++++++++++++++---
drivers/nvme/host/fabrics.c | 4 +---
drivers/nvme/host/nvme.h | 1 -
3 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 40f08e6325ef..f58e196d5b4b 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1109,6 +1109,18 @@ void nvme_execute_passthru_rq(struct request *rq)
}
EXPORT_SYMBOL_NS_GPL(nvme_execute_passthru_rq, NVME_TARGET_PASSTHRU);
+/*
+ * Recommended frequency for KATO commands per NVMe 1.4 section 7.12.1:
+ *
+ * The host should send Keep Alive commands at half of the
+ * Keep Alive Timeout accounting for transport roundtrip times [..].
+ */
+static inline void nvme_queue_keep_alive_work(struct nvme_ctrl *ctrl)
+{
+ queue_delayed_work(nvme_wq, &ctrl->ka_work,
+ ctrl->kato * HZ / 2);
+}
+
static void nvme_keep_alive_end_io(struct request *rq, blk_status_t status)
{
struct nvme_ctrl *ctrl = rq->end_io_data;
@@ -1131,7 +1143,7 @@ static void nvme_keep_alive_end_io(struct request *rq, blk_status_t status)
startka = true;
spin_unlock_irqrestore(&ctrl->lock, flags);
if (startka)
- queue_delayed_work(nvme_wq, &ctrl->ka_work, ctrl->kato * HZ);
+ nvme_queue_keep_alive_work(ctrl);
}
static int nvme_keep_alive(struct nvme_ctrl *ctrl)
@@ -1161,7 +1173,7 @@ static void nvme_keep_alive_work(struct work_struct *work)
dev_dbg(ctrl->device,
"reschedule traffic based keep-alive timer\n");
ctrl->comp_seen = false;
- queue_delayed_work(nvme_wq, &ctrl->ka_work, ctrl->kato * HZ);
+ nvme_queue_keep_alive_work(ctrl);
return;
}
@@ -1178,7 +1190,7 @@ static void nvme_start_keep_alive(struct nvme_ctrl *ctrl)
if (unlikely(ctrl->kato == 0))
return;
- queue_delayed_work(nvme_wq, &ctrl->ka_work, ctrl->kato * HZ);
+ nvme_queue_keep_alive_work(ctrl);
}
void nvme_stop_keep_alive(struct nvme_ctrl *ctrl)
diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
index 604ab0e5a2ad..13c2747e3d00 100644
--- a/drivers/nvme/host/fabrics.c
+++ b/drivers/nvme/host/fabrics.c
@@ -379,10 +379,8 @@ int nvmf_connect_admin_queue(struct nvme_ctrl *ctrl)
/*
* Set keep-alive timeout in seconds granularity (ms * 1000)
- * and add a grace period for controller kato enforcement
*/
- cmd.connect.kato = ctrl->kato ?
- cpu_to_le32((ctrl->kato + NVME_KATO_GRACE) * 1000) : 0;
+ cmd.connect.kato = cpu_to_le32(ctrl->kato * 1000);
if (ctrl->opts->disable_sqflow)
cmd.connect.cattr |= NVME_CONNECT_DISABLE_SQFLOW;
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index c6102ce83bb4..49276186d5bd 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -27,7 +27,6 @@ extern unsigned int admin_timeout;
#define NVME_ADMIN_TIMEOUT (admin_timeout * HZ)
#define NVME_DEFAULT_KATO 5
-#define NVME_KATO_GRACE 10
#ifdef CONFIG_ARCH_NO_SG_CHAIN
#define NVME_INLINE_SG_CNT 0
--
2.29.2
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^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 2/2] nvme: add 'kato' sysfs attribute
2021-04-16 11:46 [PATCHv4 0/2] nvme: sanitize KATO setting Hannes Reinecke
2021-04-16 11:46 ` [PATCH 1/2] " Hannes Reinecke
@ 2021-04-16 11:46 ` Hannes Reinecke
2021-04-20 8:07 ` [PATCHv4 0/2] nvme: sanitize KATO setting Christoph Hellwig
2 siblings, 0 replies; 4+ messages in thread
From: Hannes Reinecke @ 2021-04-16 11:46 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: Sagi Grimberg, Keith Busch, linux-nvme, Hannes Reinecke
Add a 'kato' controller sysfs attribute to display the current
keep-alive timeout value (if any). This allows userspace to identify
persistent discovery controllers, as these will have a non-zero
KATO value.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
---
drivers/nvme/host/core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f58e196d5b4b..67f0607055e8 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3173,6 +3173,7 @@ nvme_show_int_function(cntlid);
nvme_show_int_function(numa_node);
nvme_show_int_function(queue_count);
nvme_show_int_function(sqsize);
+nvme_show_int_function(kato);
static ssize_t nvme_sysfs_delete(struct device *dev,
struct device_attribute *attr, const char *buf,
@@ -3370,6 +3371,7 @@ static struct attribute *nvme_dev_attrs[] = {
&dev_attr_ctrl_loss_tmo.attr,
&dev_attr_reconnect_delay.attr,
&dev_attr_fast_io_fail_tmo.attr,
+ &dev_attr_kato.attr,
NULL
};
--
2.29.2
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^ permalink raw reply related [flat|nested] 4+ messages in thread