From: Vijay Viswanath <[email protected]>
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_MEM_RECLAIM flag enabled.
Such a workqueue will have a rescue thread which will be called
when the above deadlock condition is possible.
Signed-off-by: Vijay Viswanath <[email protected]>
Signed-off-by: Can Guo <[email protected]>
Signed-off-by: Asutosh Das <[email protected]>
---
drivers/scsi/ufs/ufshcd.c | 11 ++++++++++-
drivers/scsi/ufs/ufshcd.h | 1 +
2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 557d538..3be61b7 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1483,7 +1483,8 @@ 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.
@@ -1669,6 +1670,8 @@ 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;
@@ -1676,6 +1679,11 @@ 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 = alloc_ordered_workqueue(wq_name,
+ WQ_MEM_RECLAIM);
+
hba->clk_gating.is_enabled = true;
hba->clk_gating.delay_attr.show = ufshcd_clkgate_delay_show;
@@ -1703,6 +1711,7 @@ 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 76c31d5..2e6bdc0 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.
On 2018-05-03 04:07, Asutosh Das wrote:
> From: Vijay Viswanath <[email protected]>
>
> 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_MEM_RECLAIM flag enabled.
> Such a workqueue will have a rescue thread which will be called
> when the above deadlock condition is possible.
>
> Signed-off-by: Vijay Viswanath <[email protected]>
> Signed-off-by: Can Guo <[email protected]>
> Signed-off-by: Asutosh Das <[email protected]>
> ---
> drivers/scsi/ufs/ufshcd.c | 11 ++++++++++-
> drivers/scsi/ufs/ufshcd.h | 1 +
> 2 files changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 557d538..3be61b7 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1483,7 +1483,8 @@ 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.
> @@ -1669,6 +1670,8 @@ 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;
>
> @@ -1676,6 +1679,11 @@ 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 = alloc_ordered_workqueue(wq_name,
> + WQ_MEM_RECLAIM);
> +
> hba->clk_gating.is_enabled = true;
>
> hba->clk_gating.delay_attr.show = ufshcd_clkgate_delay_show;
> @@ -1703,6 +1711,7 @@ 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 76c31d5..2e6bdc0 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 {
Looks good to me.
Reviewed-by: Subhash Jadavani <[email protected]>
--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project