[PATCH AUTOSEL for 4.15 068/124] nvme: fix subsystem multiple controllers support check

Sasha Levin
2018-03-19T15:49:08Z

From: Israel Rukshin <israelr@mellanox.com>

[ Upstream commit b837b28394fb76993c28bb242db7061ee0417da6 ]

There is a problem when another module (e.g. nvmet) takes a reference on
the nvme block device and the physical nvme drive is removed. In that
case nvme_free_ctrl() will not be called and the controller state will be
"deleting" or "dead" unless nvmet module releases the block device.
Later on, the same nvme drive probes back and nvme_init_subsystem() will
be called and fail due to duplicate subnqn (if the nvme device doesn't
support subsystem with multiple controllers). This will cause a probe
failure. This commit changes the check of multiple controllers support
at nvme_init_subsystem() by not counting all the controllers at "dead" or
"deleting" state (this is safe because controllers at this state will
never be active again).

Fixes: ab9e00cc72fa ("nvme: track subsystems")
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Israel Rukshin <israelr@mellanox.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/nvme/host/core.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 3551fbd6fe41..935593032123 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2052,6 +2052,22 @@ static const struct attribute_group *nvme_subsys_attrs_groups[] = {
NULL,
};

+static int nvme_active_ctrls(struct nvme_subsystem *subsys)
+{
+ int count = 0;
+ struct nvme_ctrl *ctrl;
+
+ mutex_lock(&subsys->lock);
+ list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry) {
+ if (ctrl->state != NVME_CTRL_DELETING &&
+ ctrl->state != NVME_CTRL_DEAD)
+ count++;
+ }
+ mutex_unlock(&subsys->lock);
+
+ return count;
+}
+
static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
{
struct nvme_subsystem *subsys, *found;
@@ -2090,7 +2106,7 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
* Verify that the subsystem actually supports multiple
* controllers, else bail out.
*/
- if (!(id->cmic & (1 << 1))) {
+ if (nvme_active_ctrls(found) && !(id->cmic & (1 << 1))) {
dev_err(ctrl->device,
"ignoring ctrl due to duplicate subnqn (%s).\n",
found->subnqn);
--
2.14.1