This is a note to let you know that I've just added the patch titled

nvme: fix subsystem multiple controllers support check

to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: nvme-fix-subsystem-multiple-controllers-support-check.patch and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From b837b28394fb76993c28bb242db7061ee0417da6 Mon Sep 17 00:00:00 2001

From: Israel Rukshin israelr@mellanox.com Date: Thu, 4 Jan 2018 17:56:14 +0200 Subject: nvme: fix subsystem multiple controllers support check

From: Israel Rukshin israelr@mellanox.com

commit b837b28394fb76993c28bb242db7061ee0417da6 upstream.

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: Keith Busch keith.busch@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/nvme/host/core.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)

--- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -2052,6 +2052,22 @@ static const struct attribute_group *nvm 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 nv * 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);

Patches currently in stable-queue which might be from israelr@mellanox.com are

queue-4.15/nvme-fix-subsystem-multiple-controllers-support-check.patch