[PATCH] nvmet: Always remove processed AER elements from list

[Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>]

From: Daniel Wagner <dwagner@suse.de>

All async events are enqueued via nvmet_add_async_event() which
updates the ctrl->async_event_cmds[] array and additionally an struct
nvmet_async_event is added to the ctrl->async_events list.

Under normal operations the nvmet_async_event_work() updates again the
ctrl->async_event_cmds and removes the corresponding struct
nvmet_async_event from the list again. Though nvmet_sq_destroy() could
be called which calles nvmet_async_events_free() which only updates
the ctrl->async_event_cmds[] array.

Add a new function nvmet_async_events_process() which processes the
async events and updates both array and the list. With this we avoid
having two places where the array and list are modified.

When the status value is set != NVME_SC_SUCCESS that implies
nvmet_async_events_process() is called from free events context.
In this case after clearing the aen present on the ctrl->async_list we
also loop over ctrl->async_event_cmds[] for any requests posted by the
host for which we don't have the AEN in the ctrl->async_events list.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
---

Hi,

I've added the code to loop over and clear out outstanding requests
present in the ctrl->async_event_cmds[] for which aen is not generated.
Also updated the patch description.

I did the basic testing create/delete ctrl and enable/disable ns that
did not produced any hands or errors.

Regards,
Chaitanya

Following is the test log if anyone wants to take a look:-

nvmet: adding nsid 1 to subsystem fs
nvmet: creating controller 1 for subsystem fs for NQN \
nqn.2014-08.org.nvmexpress:uuid:a0b58ccb-6b6a-4045-8ee1-641816bf548d.
nvme nvme1: Please enable CONFIG_NVME_MULTIPATH for full support of multi-port devices.
nvme nvme1: creating 12 I/O queues.
nvme nvme1: new ctrl: "fs"
# nvme list | tr -s ' ' ' ' | grep Linux | grep -v '\-\-\-\-'
/dev/nvme1n1 c71f2d6a3f577a29 Linux 1 524.29 MB / 524.29 MB 1 B + 9 B 5.4.0-rc
# cat /sys/kernel/config/nvmet/subsystems/fs/namespaces/1/enable 
1
# nvme list | tr -s ' ' ' ' | grep Linux | grep -v '\-\-\-\-'
/dev/nvme1n1 c71f2d6a3f577a29 Linux 1 524.29 MB / 524.29 MB 1 B + 9 B 5.4.0-rc
# echo 0 > /sys/kernel/config/nvmet/subsystems/fs/namespaces/1/enable 
# nvme list | tr -s ' ' ' ' | grep Linux | grep -v '\-\-\-\-'
# echo 1 > /sys/kernel/config/nvmet/subsystems/fs/namespaces/1/enable 
# nvme list | tr -s ' ' ' ' | grep Linux | grep -v '\-\-\-\-'
/dev/nvme1n1 c71f2d6a3f577a29 Linux 1 524.29 MB / 524.29 MB 1 B + 9 B 5.4.0-rc
# echo 0 > /sys/kernel/config/nvmet/subsystems/fs/namespaces/1/enable 
# nvme list | tr -s ' ' ' ' | grep Linux | grep -v '\-\-\-\-'
# echo 1 > /sys/kernel/config/nvmet/subsystems/fs/namespaces/1/enable 


---
 drivers/nvme/target/core.c | 49 ++++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 21 deletions(-)

diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 28438b833c1b..5f7f6fd864fb 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -129,11 +129,32 @@ static u32 nvmet_async_event_result(struct nvmet_async_event *aen)
 	return aen->event_type | (aen->event_info << 8) | (aen->log_page << 16);
 }
 
-static void nvmet_async_events_free(struct nvmet_ctrl *ctrl)
+static void nvmet_async_events_process(struct nvmet_ctrl *ctrl, u16 status)
 {
+	struct nvmet_async_event *aen;
 	struct nvmet_req *req;
 
 	while (1) {
+		mutex_lock(&ctrl->lock);
+		aen = list_first_entry_or_null(&ctrl->async_events,
+				struct nvmet_async_event, entry);
+		if (!aen || !ctrl->nr_async_event_cmds) {
+			mutex_unlock(&ctrl->lock);
+			break;
+		}
+
+		req = ctrl->async_event_cmds[--ctrl->nr_async_event_cmds];
+		if (status == 0)
+			nvmet_set_result(req, nvmet_async_event_result(aen));
+
+		list_del(&aen->entry);
+		kfree(aen);
+
+		mutex_unlock(&ctrl->lock);
+		nvmet_req_complete(req, status);
+	}
+
+	while (status) {
 		mutex_lock(&ctrl->lock);
 		if (!ctrl->nr_async_event_cmds) {
 			mutex_unlock(&ctrl->lock);
@@ -146,31 +167,17 @@ static void nvmet_async_events_free(struct nvmet_ctrl *ctrl)
 	}
 }
 
+static void nvmet_async_events_free(struct nvmet_ctrl *ctrl)
+{
+	nvmet_async_events_process(ctrl, NVME_SC_INTERNAL | NVME_SC_DNR);
+}
+
 static void nvmet_async_event_work(struct work_struct *work)
 {
 	struct nvmet_ctrl *ctrl =
 		container_of(work, struct nvmet_ctrl, async_event_work);
-	struct nvmet_async_event *aen;
-	struct nvmet_req *req;
-
-	while (1) {
-		mutex_lock(&ctrl->lock);
-		aen = list_first_entry_or_null(&ctrl->async_events,
-				struct nvmet_async_event, entry);
-		if (!aen || !ctrl->nr_async_event_cmds) {
-			mutex_unlock(&ctrl->lock);
-			return;
-		}
-
-		req = ctrl->async_event_cmds[--ctrl->nr_async_event_cmds];
-		nvmet_set_result(req, nvmet_async_event_result(aen));
 
-		list_del(&aen->entry);
-		kfree(aen);
-
-		mutex_unlock(&ctrl->lock);
-		nvmet_req_complete(req, 0);
-	}
+	nvmet_async_events_process(ctrl, 0);
 }
 
 void nvmet_add_async_event(struct nvmet_ctrl *ctrl, u8 event_type,
-- 
2.22.1


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