linux-kernel - [RFC] nvme: Do not reject dynamic controller cntlid

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Date:   Thu, 27 Jan 2022 14:36:48 +0100
From:   Daniel Wagner <dwagner@...e.de>
To:     linux-nvme@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, Daniel Wagner <dwagner@...e.de>
Subject: [RFC] nvme: Do not reject dynamic controller cntlid

The NVME spec states in 3.1.1 Controller Model there are two types
controllers: dynamic and static.

The nvme_validate_cntlid() check ensures that the newly discovered
controller does not have the same cntlid as a known controller. For
the dynamic controller model this check doesn't make sense as all
cntlid will be 0xffff. In this case ignore this check.

Signed-off-by: Daniel Wagner <dwagner@...e.de>
---

I got a bug report with this:

 nvme nvme10: pci function 0000:00:19.0
 nvme 0000:00:19.0: enabling device (0000 -> 0002)
 nvme nvme10: Duplicate cntlid 65535 with nvme7, rejecting
 nvme nvme10: Removing after probe failure status: -22

>From reading the spec I got the impression that it should be enough to
ignore the cntlid check if the cntlid is 0xffff. Though I might be
completely wrong here.

 drivers/nvme/host/core.c | 2 +-
 drivers/nvme/host/nvme.h | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index dd18861f77c0..918abb54771c 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2701,7 +2701,7 @@ static bool nvme_validate_cntlid(struct nvme_subsystem *subsys,
 		if (nvme_state_terminal(tmp))
 			continue;
 
-		if (tmp->cntlid == ctrl->cntlid) {
+		if (!nvme_ctrl_dynamic(tmp) && tmp->cntlid == ctrl->cntlid) {
 			dev_err(ctrl->device,
 				"Duplicate cntlid %u with %s, subsys %s, rejecting\n",
 				ctrl->cntlid, dev_name(tmp->device),
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index a162f6c6da6e..ed75245263f5 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -539,6 +539,11 @@ static inline struct request *nvme_cid_to_rq(struct blk_mq_tags *tags,
 	return blk_mq_tag_to_rq(tags, nvme_tag_from_cid(command_id));
 }
 
+static inline bool nvme_ctrl_dynamic(struct nvme_ctrl *ctrl)
+{
+	return ctrl->cntlid == 0xffff;
+}
+
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
 void nvme_fault_inject_init(struct nvme_fault_inject *fault_inj,
 			    const char *dev_name);
-- 
2.29.2