Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 3b284d45 authored by Asutosh Das's avatar Asutosh Das
Browse files

scsi: ufs: fix deadlock between clock scaling and shutdown 



There's a deadlock in which shutdown context is waiting for
a mutex acquired by clock-scaling monitor, which in turn is
waiting for the mutex acquired by shutdown context.
Fix this by not allowing clocks to scale after being
suspended & also de-register this device from the devfreq
framework.

As below:
<call stack : init>
-005|current_thread_info(inline)
-005|mutex_set_owner(inline)
-005|mutex_lock
-006|devfreq_monitor_suspend
-007|devfreq_simple_ondemand_handler
-008|devfreq_suspend_device(?)
-009|__ufshcd_suspend_clkscaling(inline)
-009|ufshcd_suspend_clkscaling
-010|ufshcd_shutdown
-011|ufshcd_pltfrm_shutdown(?)
-012|platform_drv_shutdown
-013|device_unlock(inline)
-013|device_shutdown()
-014|kernel_restart_prepare(?)
-015|kernel_restart
-016|SYSC_reboot(inline)
-016|sys_reboot(?, ?, ?)
-017|el0_svc_naked(asm)
-->|exception
-018|NUX:0x538F6C(asm)

<call stack : kworker/u16:4>
-008|rwsem_down_write_failed
    |    sem = -> (
    |      count = -8589934591,
    |      wait_list = (next = , prev = ),
    |      wait_lock = (raw_lock = (owner = 4, next = 4)),
    |      osq = (tail = (counter = 0)),
    |      owner = -> (
    |      comm = "init",
-009|current_thread_info(inline)
-009|rwsem_set_owner(inline)
-009|down_write
-010|ufshcd_clock_scaling_prepare(inline)
-010|ufshcd_devfreq_scale
-011|ufshcd_devfreq_target(?, ?, ?)
-012|update_devfreq
-013|devfreq_monitor
-014|__read_once_size(inline)
-014|static_key_count(inline)
-014|static_key_false(inline)
-014|trace_workqueue_execute_end(inline)
-014|process_one_work
-015|worker_thread
-016|kthread
-017|ret_from_fork(asm)
---|end of frame

Change-Id: Ic1853ef5143cadd95f0a6df474b35ad45fa918e1
Signed-off-by: default avatarAsutosh Das <asutoshd@codeaurora.org>
parent c7835c57

drivers/scsi/ufs/ufshcd.c

+33 −10
Original line number Diff line number Diff line
@@ -8790,6 +8790,35 @@ static inline void ufshcd_add_sysfs_nodes(struct ufs_hba *hba) 
	ufshcd_add_spm_lvl_sysfs_nodes(hba);

}



static void ufshcd_shutdown_clkscaling(struct ufs_hba *hba)

{

	bool suspend = false;

	unsigned long flags;



	spin_lock_irqsave(hba->host->host_lock, flags);

	if (hba->clk_scaling.is_allowed) {

		hba->clk_scaling.is_allowed = false;

		suspend = true;

	}

	spin_unlock_irqrestore(hba->host->host_lock, flags);



	/**

	 * Scaling may be scheduled before, hence make sure it

	 * doesn't race with shutdown

	 */

	if (ufshcd_is_clkscaling_supported(hba)) {

		device_remove_file(hba->dev, &hba->clk_scaling.enable_attr);

		cancel_work_sync(&hba->clk_scaling.suspend_work);

		cancel_work_sync(&hba->clk_scaling.resume_work);

		if (suspend)

			ufshcd_suspend_clkscaling(hba);

	}



	/* Unregister so that devfreq_monitor can't race with shutdown */

	if (hba->devfreq)

		devfreq_remove_device(hba->devfreq);

}



/**

 * ufshcd_shutdown - shutdown routine

 * @hba: per adapter instance
@@ -8807,16 +8836,14 @@ int ufshcd_shutdown(struct ufs_hba *hba) 


	pm_runtime_get_sync(hba->dev);

	ufshcd_hold_all(hba);

	ufshcd_mark_shutdown_ongoing(hba);

	ufshcd_shutdown_clkscaling(hba);

	/**

	 * (1) Set state to shutting down

	 * (2) Acquire the lock to stop any more requests

	 * (3) Suspend clock scaling

	 * (4) Wait for all issued requests to complete

	 * (1) Acquire the lock to stop any more requests

	 * (2) Wait for all issued requests to complete

	 */

	ufshcd_mark_shutdown_ongoing(hba);

	ufshcd_get_write_lock(hba);

	ufshcd_scsi_block_requests(hba);

	ufshcd_suspend_clkscaling(hba);

	ret = ufshcd_wait_for_doorbell_clr(hba, U64_MAX);

	if (ret)

		dev_err(hba->dev, "%s: waiting for DB clear: failed: %d\n",
@@ -9210,10 +9237,6 @@ static void ufshcd_clk_scaling_resume_work(struct work_struct *work) 
					   clk_scaling.resume_work);

	unsigned long irq_flags;



	/* Let's not resume scaling if shutdown is ongoing */

	if (ufshcd_is_shutdown_ongoing(hba))

		return;



	spin_lock_irqsave(hba->host->host_lock, irq_flags);

	if (!hba->clk_scaling.is_suspended) {

		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);