[PATCH v3 1/3] scsi: ufs: Protect some contexts from unexpected clock scaling

[PATCH v3 1/3] scsi: ufs: Protect some contexts from unexpected clock scaling

[Can Guo]

In contexts like suspend, shutdown and error handling, we need to suspend
devfreq to make sure these contexts won't be disturbed by clock scaling.
However, suspending devfreq is not enough since users can still trigger a
clock scaling by manipulating the sysfs node clkscale_enable and devfreq
sysfs nodes like min/max_freq and governor. Add one more flag in struct
clk_scaling such that these contexts can prevent clock scaling from being
invoked through above sysfs nodes.

Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 84 +++++++++++++++++++++++++++++++----------------
 drivers/scsi/ufs/ufshcd.h |  2 ++
 2 files changed, 58 insertions(+), 28 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 0c148fc..59dac09 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1147,12 +1147,23 @@ static int ufshcd_clock_scaling_prepare(struct ufs_hba *hba)
 	 */
 	ufshcd_scsi_block_requests(hba);
 	down_write(&hba->clk_scaling_lock);
-	if (ufshcd_wait_for_doorbell_clr(hba, DOORBELL_CLR_TOUT_US)) {
+
+	if (!hba->clk_scaling.is_allowed)
+		ret = -EAGAIN;
+
+	if (ufshcd_wait_for_doorbell_clr(hba, DOORBELL_CLR_TOUT_US))
 		ret = -EBUSY;
+
+	if (ret) {
 		up_write(&hba->clk_scaling_lock);
 		ufshcd_scsi_unblock_requests(hba);
+		goto out;
 	}
 
+	/* let's not get into low power until clock scaling is completed */
+	ufshcd_hold(hba, false);
+
+out:
 	return ret;
 }
 
@@ -1160,6 +1171,7 @@ static void ufshcd_clock_scaling_unprepare(struct ufs_hba *hba)
 {
 	up_write(&hba->clk_scaling_lock);
 	ufshcd_scsi_unblock_requests(hba);
+	ufshcd_release(hba);
 }
 
 /**
@@ -1175,12 +1187,9 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
 {
 	int ret = 0;
 
-	/* let's not get into low power until clock scaling is completed */
-	ufshcd_hold(hba, false);
-
 	ret = ufshcd_clock_scaling_prepare(hba);
 	if (ret)
-		goto out;
+		return ret;
 
 	/* scale down the gear before scaling down clocks */
 	if (!scale_up) {
@@ -1212,8 +1221,6 @@ static int ufshcd_devfreq_scale(struct ufs_hba *hba, bool scale_up)
 
 out_unprepare:
 	ufshcd_clock_scaling_unprepare(hba);
-out:
-	ufshcd_release(hba);
 	return ret;
 }
 
@@ -1487,7 +1494,7 @@ static ssize_t ufshcd_clkscale_enable_show(struct device *dev,
 {
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 
-	return snprintf(buf, PAGE_SIZE, "%d\n", hba->clk_scaling.is_allowed);
+	return snprintf(buf, PAGE_SIZE, "%d\n", hba->clk_scaling.is_enabled);
 }
 
 static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
@@ -1496,12 +1503,20 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
 	struct ufs_hba *hba = dev_get_drvdata(dev);
 	u32 value;
 	int err;
+	unsigned long flags;
+	bool update = true;
 
 	if (kstrtou32(buf, 0, &value))
 		return -EINVAL;
 
 	value = !!value;
-	if (value == hba->clk_scaling.is_allowed)
+	spin_lock_irqsave(hba->host->host_lock, flags);
+	if (value == hba->clk_scaling.is_enabled)
+		update = false;
+	else
+		hba->clk_scaling.is_enabled = value;
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	if (!update)
 		goto out;
 
 	pm_runtime_get_sync(hba->dev);
@@ -1510,8 +1525,6 @@ static ssize_t ufshcd_clkscale_enable_store(struct device *dev,
 	cancel_work_sync(&hba->clk_scaling.suspend_work);
 	cancel_work_sync(&hba->clk_scaling.resume_work);
 
-	hba->clk_scaling.is_allowed = value;
-
 	if (value) {
 		ufshcd_resume_clkscaling(hba);
 	} else {
@@ -1845,8 +1858,6 @@ static void ufshcd_init_clk_scaling(struct ufs_hba *hba)
 	snprintf(wq_name, sizeof(wq_name), "ufs_clkscaling_%d",
 		 hba->host->host_no);
 	hba->clk_scaling.workq = create_singlethread_workqueue(wq_name);
-
-	ufshcd_clkscaling_init_sysfs(hba);
 }
 
 static void ufshcd_exit_clk_scaling(struct ufs_hba *hba)
@@ -1854,6 +1865,8 @@ static void ufshcd_exit_clk_scaling(struct ufs_hba *hba)
 	if (!ufshcd_is_clkscaling_supported(hba))
 		return;
 
+	if (hba->devfreq)
+		device_remove_file(hba->dev, &hba->clk_scaling.enable_attr);
 	destroy_workqueue(hba->clk_scaling.workq);
 	ufshcd_devfreq_remove(hba);
 }
@@ -1918,7 +1931,7 @@ static void ufshcd_clk_scaling_start_busy(struct ufs_hba *hba)
 	if (!hba->clk_scaling.active_reqs++)
 		queue_resume_work = true;
 
-	if (!hba->clk_scaling.is_allowed || hba->pm_op_in_progress)
+	if (!hba->clk_scaling.is_enabled || hba->pm_op_in_progress)
 		return;
 
 	if (queue_resume_work)
@@ -4987,7 +5000,8 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba,
 				complete(hba->dev_cmd.complete);
 			}
 		}
-		if (ufshcd_is_clkscaling_supported(hba))
+		if (ufshcd_is_clkscaling_supported(hba) &&
+		    hba->clk_scaling.active_reqs > 0)
 			hba->clk_scaling.active_reqs--;
 	}
 
@@ -5650,18 +5664,25 @@ static void ufshcd_err_handling_prepare(struct ufs_hba *hba)
 		ufshcd_vops_resume(hba, UFS_RUNTIME_PM);
 	} else {
 		ufshcd_hold(hba, false);
-		if (hba->clk_scaling.is_allowed) {
+		if (hba->clk_scaling.is_enabled) {
 			cancel_work_sync(&hba->clk_scaling.suspend_work);
 			cancel_work_sync(&hba->clk_scaling.resume_work);
 			ufshcd_suspend_clkscaling(hba);
 		}
 	}
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = false;
+	up_write(&hba->clk_scaling_lock);
 }
 
 static void ufshcd_err_handling_unprepare(struct ufs_hba *hba)
 {
 	ufshcd_release(hba);
-	if (hba->clk_scaling.is_allowed)
+
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = true;
+	up_write(&hba->clk_scaling_lock);
+	if (hba->clk_scaling.is_enabled)
 		ufshcd_resume_clkscaling(hba);
 	pm_runtime_put(hba->dev);
 }
@@ -7620,12 +7641,14 @@ static int ufshcd_add_lus(struct ufs_hba *hba)
 			sizeof(struct ufs_pa_layer_attr));
 		hba->clk_scaling.saved_pwr_info.is_valid = true;
 		if (!hba->devfreq) {
+			hba->clk_scaling.is_allowed = true;
 			ret = ufshcd_devfreq_init(hba);
 			if (ret)
 				goto out;
-		}
 
-		hba->clk_scaling.is_allowed = true;
+			hba->clk_scaling.is_enabled = true;
+			ufshcd_clkscaling_init_sysfs(hba);
+		}
 	}
 
 	ufs_bsg_probe(hba);
@@ -8491,11 +8514,14 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	ufshcd_hold(hba, false);
 	hba->clk_gating.is_suspended = true;
 
-	if (hba->clk_scaling.is_allowed) {
+	if (hba->clk_scaling.is_enabled) {
 		cancel_work_sync(&hba->clk_scaling.suspend_work);
 		cancel_work_sync(&hba->clk_scaling.resume_work);
 		ufshcd_suspend_clkscaling(hba);
 	}
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = false;
+	up_write(&hba->clk_scaling_lock);
 
 	if (req_dev_pwr_mode == UFS_ACTIVE_PWR_MODE &&
 			req_link_state == UIC_LINK_ACTIVE_STATE) {
@@ -8592,8 +8618,6 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	goto out;
 
 set_link_active:
-	if (hba->clk_scaling.is_allowed)
-		ufshcd_resume_clkscaling(hba);
 	ufshcd_vreg_set_hpm(hba);
 	if (ufshcd_is_link_hibern8(hba) && !ufshcd_uic_hibern8_exit(hba))
 		ufshcd_set_link_active(hba);
@@ -8603,7 +8627,10 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	if (!ufshcd_set_dev_pwr_mode(hba, UFS_ACTIVE_PWR_MODE))
 		ufshcd_disable_auto_bkops(hba);
 enable_gating:
-	if (hba->clk_scaling.is_allowed)
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = true;
+	up_write(&hba->clk_scaling_lock);
+	if (hba->clk_scaling.is_enabled)
 		ufshcd_resume_clkscaling(hba);
 	hba->clk_gating.is_suspended = false;
 	hba->dev_info.b_rpm_dev_flush_capable = false;
@@ -8701,7 +8728,10 @@ static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 
 	hba->clk_gating.is_suspended = false;
 
-	if (hba->clk_scaling.is_allowed)
+	down_write(&hba->clk_scaling_lock);
+	hba->clk_scaling.is_allowed = true;
+	up_write(&hba->clk_scaling_lock);
+	if (hba->clk_scaling.is_enabled)
 		ufshcd_resume_clkscaling(hba);
 
 	/* Enable Auto-Hibernate if configured */
@@ -8725,8 +8755,6 @@ static int ufshcd_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	ufshcd_vreg_set_lpm(hba);
 disable_irq_and_vops_clks:
 	ufshcd_disable_irq(hba);
-	if (hba->clk_scaling.is_allowed)
-		ufshcd_suspend_clkscaling(hba);
 	ufshcd_setup_clocks(hba, false);
 	if (ufshcd_is_clkgating_allowed(hba)) {
 		hba->clk_gating.state = CLKS_OFF;
@@ -8915,6 +8943,8 @@ int ufshcd_shutdown(struct ufs_hba *hba)
 
 	pm_runtime_get_sync(hba->dev);
 
+	ufshcd_exit_clk_scaling(hba);
+
 	ret = ufshcd_suspend(hba, UFS_SHUTDOWN_PM);
 out:
 	if (ret)
@@ -8944,8 +8974,6 @@ void ufshcd_remove(struct ufs_hba *hba)
 
 	ufshcd_exit_clk_scaling(hba);
 	ufshcd_exit_clk_gating(hba);
-	if (ufshcd_is_clkscaling_supported(hba))
-		device_remove_file(hba->dev, &hba->clk_scaling.enable_attr);
 	ufshcd_hba_exit(hba);
 }
 EXPORT_SYMBOL_GPL(ufshcd_remove);
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index e0f00a4..9fcecba 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -382,6 +382,7 @@ struct ufs_saved_pwr_info {
  * @workq: workqueue to schedule devfreq suspend/resume work
  * @suspend_work: worker to suspend devfreq
  * @resume_work: worker to resume devfreq
+ * @is_enabled: tracks if scaling is currently enabled or not
  * @is_allowed: tracks if scaling is currently allowed or not
  * @is_busy_started: tracks if busy period has started or not
  * @is_suspended: tracks if devfreq is suspended or not
@@ -396,6 +397,7 @@ struct ufs_clk_scaling {
 	struct workqueue_struct *workq;
 	struct work_struct suspend_work;
 	struct work_struct resume_work;
+	bool is_enabled;
 	bool is_allowed;
 	bool is_busy_started;
 	bool is_suspended;
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

[PATCH v3 2/3] scsi: ufs: Clean up ufshcd_exit_clk_scaling/gating()

[Can Guo]

ufshcd_hba_exit() is always called after ufshcd_exit_clk_scaling() and
ufshcd_exit_clk_gating(), so move ufshcd_exit_clk_scaling/gating() to
ufshcd_hba_exit().

Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 32 +++++++++++++++-----------------
 drivers/scsi/ufs/ufshcd.h |  4 ++++
 2 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 59dac09..f2ca087 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1858,11 +1858,14 @@ static void ufshcd_init_clk_scaling(struct ufs_hba *hba)
 	snprintf(wq_name, sizeof(wq_name), "ufs_clkscaling_%d",
 		 hba->host->host_no);
 	hba->clk_scaling.workq = create_singlethread_workqueue(wq_name);
+
+	hba->clk_scaling.is_initialized = true;
 }
 
 static void ufshcd_exit_clk_scaling(struct ufs_hba *hba)
 {
-	if (!ufshcd_is_clkscaling_supported(hba))
+	if (!ufshcd_is_clkscaling_supported(hba) ||
+	    !hba->clk_scaling.is_initialized)
 		return;
 
 	if (hba->devfreq)
@@ -1906,12 +1909,16 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba)
 	hba->clk_gating.enable_attr.attr.mode = 0644;
 	if (device_create_file(hba->dev, &hba->clk_gating.enable_attr))
 		dev_err(hba->dev, "Failed to create sysfs for clkgate_enable\n");
+
+	hba->clk_gating.is_initialized = true;
 }
 
 static void ufshcd_exit_clk_gating(struct ufs_hba *hba)
 {
-	if (!ufshcd_is_clkgating_allowed(hba))
+	if (!ufshcd_is_clkgating_allowed(hba) ||
+	    !hba->clk_gating.is_initialized)
 		return;
+
 	device_remove_file(hba->dev, &hba->clk_gating.delay_attr);
 	device_remove_file(hba->dev, &hba->clk_gating.enable_attr);
 	cancel_work_sync(&hba->clk_gating.ungate_work);
@@ -7776,7 +7783,6 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
 	 */
 	if (ret) {
 		pm_runtime_put_sync(hba->dev);
-		ufshcd_exit_clk_scaling(hba);
 		ufshcd_hba_exit(hba);
 	}
 }
@@ -8213,12 +8219,12 @@ static int ufshcd_hba_init(struct ufs_hba *hba)
 static void ufshcd_hba_exit(struct ufs_hba *hba)
 {
 	if (hba->is_powered) {
+		ufshcd_exit_clk_scaling(hba);
+		ufshcd_exit_clk_gating(hba);
+		if (hba->eh_wq)
+			destroy_workqueue(hba->eh_wq);
 		ufshcd_variant_hba_exit(hba);
 		ufshcd_setup_vreg(hba, false);
-		ufshcd_suspend_clkscaling(hba);
-		if (ufshcd_is_clkscaling_supported(hba))
-			if (hba->devfreq)
-				ufshcd_suspend_clkscaling(hba);
 		ufshcd_setup_clocks(hba, false);
 		ufshcd_setup_hba_vreg(hba, false);
 		hba->is_powered = false;
@@ -8967,13 +8973,9 @@ void ufshcd_remove(struct ufs_hba *hba)
 	blk_mq_free_tag_set(&hba->tmf_tag_set);
 	blk_cleanup_queue(hba->cmd_queue);
 	scsi_remove_host(hba->host);
-	destroy_workqueue(hba->eh_wq);
 	/* disable interrupts */
 	ufshcd_disable_intr(hba, hba->intr_mask);
 	ufshcd_hba_stop(hba);
-
-	ufshcd_exit_clk_scaling(hba);
-	ufshcd_exit_clk_gating(hba);
 	ufshcd_hba_exit(hba);
 }
 EXPORT_SYMBOL_GPL(ufshcd_remove);
@@ -9172,7 +9174,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 	err = devm_request_irq(dev, irq, ufshcd_intr, IRQF_SHARED, UFSHCD, hba);
 	if (err) {
 		dev_err(hba->dev, "request irq failed\n");
-		goto exit_gating;
+		goto out_disable;
 	} else {
 		hba->is_irq_enabled = true;
 	}
@@ -9180,7 +9182,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 	err = scsi_add_host(host, hba->dev);
 	if (err) {
 		dev_err(hba->dev, "scsi_add_host failed\n");
-		goto exit_gating;
+		goto out_disable;
 	}
 
 	hba->cmd_queue = blk_mq_init_queue(&hba->host->tag_set);
@@ -9263,10 +9265,6 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 	blk_cleanup_queue(hba->cmd_queue);
 out_remove_scsi_host:
 	scsi_remove_host(hba->host);
-exit_gating:
-	ufshcd_exit_clk_scaling(hba);
-	ufshcd_exit_clk_gating(hba);
-	destroy_workqueue(hba->eh_wq);
 out_disable:
 	hba->is_irq_enabled = false;
 	ufshcd_hba_exit(hba);
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 9fcecba..3c57847 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -347,6 +347,7 @@ enum clk_gating_state {
  * @delay_attr: sysfs attribute to control delay_attr
  * @enable_attr: sysfs attribute to enable/disable clock gating
  * @is_enabled: Indicates the current status of clock gating
+ * @is_initialized: Indicates whether clock gating is initialized or not
  * @active_reqs: number of requests that are pending and should be waited for
  * completion before gating clocks.
  */
@@ -359,6 +360,7 @@ struct ufs_clk_gating {
 	struct device_attribute delay_attr;
 	struct device_attribute enable_attr;
 	bool is_enabled;
+	bool is_initialized;
 	int active_reqs;
 	struct workqueue_struct *clk_gating_workq;
 };
@@ -384,6 +386,7 @@ struct ufs_saved_pwr_info {
  * @resume_work: worker to resume devfreq
  * @is_enabled: tracks if scaling is currently enabled or not
  * @is_allowed: tracks if scaling is currently allowed or not
+ * @is_initialized: Indicates whether clock scaling is initialized or not
  * @is_busy_started: tracks if busy period has started or not
  * @is_suspended: tracks if devfreq is suspended or not
  */
@@ -399,6 +402,7 @@ struct ufs_clk_scaling {
 	struct work_struct resume_work;
 	bool is_enabled;
 	bool is_allowed;
+	bool is_initialized;
 	bool is_busy_started;
 	bool is_suspended;
 };
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

[PATCH v3 3/3] scsi: ufs: Revert "Make sure clk scaling happens only when HBA is runtime ACTIVE"

[Can Guo]

Commit 73cc291c27024 ("Make sure clk scaling happens only when HBA is
runtime ACTIVE") is no longer needed since commit f7a42540928a8 ("scsi:
ufs: Protect some contexts from unexpected clock scaling") is a more
mature fix to protect UFS LLD stability from clock scaling invoked through
sysfs nodes by users.

Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index f2ca087..7f79e05 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1301,15 +1301,8 @@ static int ufshcd_devfreq_target(struct device *dev,
 	}
 	spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
 
-	pm_runtime_get_noresume(hba->dev);
-	if (!pm_runtime_active(hba->dev)) {
-		pm_runtime_put_noidle(hba->dev);
-		ret = -EAGAIN;
-		goto out;
-	}
 	start = ktime_get();
 	ret = ufshcd_devfreq_scale(hba, scale_up);
-	pm_runtime_put(hba->dev);
 
 	trace_ufshcd_profile_clk_scaling(dev_name(hba->dev),
 		(scale_up ? "up" : "down"),
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.