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

nvmet: confirm sq percpu has scheduled and switched to atomic

to the 4.9-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: nvmet-confirm-sq-percpu-has-scheduled-and-switched-to-atomic.patch and it can be found in the queue-4.9 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 foo@baz Mon Dec 18 14:12:34 CET 2017

From: Sagi Grimberg sagi@grimberg.me Date: Mon, 6 Mar 2017 18:46:20 +0200 Subject: nvmet: confirm sq percpu has scheduled and switched to atomic

From: Sagi Grimberg sagi@grimberg.me

[ Upstream commit d11ea004a458b982e19b188c386e25a9b66ec446 ]

percpu_ref_kill is not enough to prevent subsequent percpu_ref_tryget_live from failing. Hence call perfcpu_ref_kill_confirm to make it safe.

Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Sagi Grimberg sagi@grimberg.me Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/nvme/target/core.c | 11 ++++++++++- drivers/nvme/target/nvmet.h | 1 + 2 files changed, 11 insertions(+), 1 deletion(-)

--- a/drivers/nvme/target/core.c +++ b/drivers/nvme/target/core.c @@ -422,6 +422,13 @@ void nvmet_sq_setup(struct nvmet_ctrl *c ctrl->sqs[qid] = sq; }

+static void nvmet_confirm_sq(struct percpu_ref *ref) +{ + struct nvmet_sq *sq = container_of(ref, struct nvmet_sq, ref); + + complete(&sq->confirm_done); +} + void nvmet_sq_destroy(struct nvmet_sq *sq) { /* @@ -430,7 +437,8 @@ void nvmet_sq_destroy(struct nvmet_sq *s */ if (sq->ctrl && sq->ctrl->sqs && sq->ctrl->sqs[0] == sq) nvmet_async_events_free(sq->ctrl); - percpu_ref_kill(&sq->ref); + percpu_ref_kill_and_confirm(&sq->ref, nvmet_confirm_sq); + wait_for_completion(&sq->confirm_done); wait_for_completion(&sq->free_done); percpu_ref_exit(&sq->ref);

@@ -458,6 +466,7 @@ int nvmet_sq_init(struct nvmet_sq *sq) return ret; } init_completion(&sq->free_done); + init_completion(&sq->confirm_done);

return 0; } --- a/drivers/nvme/target/nvmet.h +++ b/drivers/nvme/target/nvmet.h @@ -73,6 +73,7 @@ struct nvmet_sq { u16 qid; u16 size; struct completion free_done; + struct completion confirm_done; };

/**

Patches currently in stable-queue which might be from sagi@grimberg.me are

queue-4.9/blk-mq-fix-tagset-reinit-in-the-presence-of-cpu-hot-unplug.patch queue-4.9/nvmet-confirm-sq-percpu-has-scheduled-and-switched-to-atomic.patch queue-4.9/nvme-use-kref_get_unless_zero-in-nvme_find_get_ns.patch queue-4.9/nvme-loop-fix-a-possible-use-after-free-when-destroying-the-admin-queue.patch queue-4.9/nvmet-rdma-fix-a-possible-uninitialized-variable-dereference.patch