On Wed, Feb 21, 2018 at 5:56 AM, Asutosh Das <asuto...@codeaurora.org> wrote:
> From: Vijay Viswanath <vvisw...@codeaurora.org>
>
> UFS driver can receive a request during memory reclaim by kswapd.
> So when ufs driver puts the ungate work in queue, and if there are no
> idle workers, kthreadd is invoked to create a new kworker. Since
> kswapd task holds a mutex which kthreadd also needs, this can cause
> a deadlock situation. So ungate work must be done in a separate
> work queue with WQ__RECLAIM flag enabled.Such a workqueue will have
WQ_MEM_RECLAIM here. Also space after dot.
> a rescue thread which will be called when the above deadlock
> condition is possible.
>
> Signed-off-by: Vijay Viswanath <vvisw...@codeaurora.org>
> Signed-off-by: Can Guo <c...@codeaurora.org>
> Signed-off-by: Asutosh Das <asuto...@codeaurora.org>
> ---
> drivers/scsi/ufs/ufshcd.c | 10 +++++++++-
> drivers/scsi/ufs/ufshcd.h | 1 +
> 2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 6541e1d..bb3382a 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1503,7 +1503,8 @@ int ufshcd_hold(struct ufs_hba *hba, bool async)
> hba->clk_gating.state = REQ_CLKS_ON;
> trace_ufshcd_clk_gating(dev_name(hba->dev),
> hba->clk_gating.state);
> - schedule_work(&hba->clk_gating.ungate_work);
> + queue_work(hba->clk_gating.clk_gating_workq,
> + &hba->clk_gating.ungate_work);
> /*
> * fall through to check if we should wait for this
> * work to be done or not.
> @@ -1689,6 +1690,8 @@ static ssize_t ufshcd_clkgate_enable_store(struct
> device *dev,
>
> static void ufshcd_init_clk_gating(struct ufs_hba *hba)
> {
> + char wq_name[sizeof("ufs_clk_gating_00")];
> +
> if (!ufshcd_is_clkgating_allowed(hba))
> return;
>
> @@ -1696,6 +1699,10 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba)
> INIT_DELAYED_WORK(&hba->clk_gating.gate_work, ufshcd_gate_work);
> INIT_WORK(&hba->clk_gating.ungate_work, ufshcd_ungate_work);
>
> + snprintf(wq_name, ARRAY_SIZE(wq_name), "ufs_clk_gating_%d",
> + hba->host->host_no);
> + hba->clk_gating.clk_gating_workq =
> create_singlethread_workqueue(wq_name);
Shouldn't this be alloc_ordered_workqueue() with WQ_MEM_RECLAIM then?
(create_singlethread_workqueue() and friends are deprecated).
Cheers,
Miguel
> +
> hba->clk_gating.is_enabled = true;
>
> hba->clk_gating.delay_attr.show = ufshcd_clkgate_delay_show;
> @@ -1723,6 +1730,7 @@ static void ufshcd_exit_clk_gating(struct ufs_hba *hba)
> device_remove_file(hba->dev, &hba->clk_gating.enable_attr);
> cancel_work_sync(&hba->clk_gating.ungate_work);
> cancel_delayed_work_sync(&hba->clk_gating.gate_work);
> + destroy_workqueue(hba->clk_gating.clk_gating_workq);
> }
>
> /* Must be called with host lock acquired */
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 4385741..570c33e 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -361,6 +361,7 @@ struct ufs_clk_gating {
> struct device_attribute enable_attr;
> bool is_enabled;
> int active_reqs;
> + struct workqueue_struct *clk_gating_workq;
> };
>
> struct ufs_saved_pwr_info {
> --
> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
> Foundation Collaborative Project.
>
