evie/android_kernel_oneplus_msm8998
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scsi: ufs: Add clock ungating to a separate workqueue

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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
a rescue thread which will be called when the above deadlock
condition is possible.

Change-Id: I91c5bff812be403addc98fbb8c620e67cf28f5d9
Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org>
This commit is contained in:
Vijay Viswanath 2016-11-15 11:02:03 +05:30
parent 55e8426a19
commit db0785db9a
2 changed files with 9 additions and 1 deletions
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9
drivers/scsi/ufs/ufshcd.c
View file

@ -1344,7 +1344,8 @@ start:
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.ungating_workq,
&hba->clk_gating.ungate_work);
/*
* fall through to check if we should wait for this
* work to be done or not.
@ -1617,6 +1618,7 @@ static enum hrtimer_restart ufshcd_clkgate_hrtimer_handler(
static void ufshcd_init_clk_gating(struct ufs_hba *hba)
{
struct ufs_clk_gating *gating = &hba->clk_gating;
char wq_name[sizeof("ufs_clk_ungating_00")];
hba->clk_gating.state = CLKS_ON;
@ -1645,6 +1647,10 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba)
hrtimer_init(&gating->gate_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
gating->gate_hrtimer.function = ufshcd_clkgate_hrtimer_handler;
snprintf(wq_name, ARRAY_SIZE(wq_name), "ufs_clk_ungating_%d",
hba->host->host_no);
hba->clk_gating.ungating_workq = create_singlethread_workqueue(wq_name);
gating->is_enabled = true;
gating->delay_ms_pwr_save = UFSHCD_CLK_GATING_DELAY_MS_PWR_SAVE;
@ -1707,6 +1713,7 @@ static void ufshcd_exit_clk_gating(struct ufs_hba *hba)
device_remove_file(hba->dev, &hba->clk_gating.enable_attr);
ufshcd_cancel_gate_work(hba);
cancel_work_sync(&hba->clk_gating.ungate_work);
destroy_workqueue(hba->clk_gating.ungating_workq);
}
static void ufshcd_set_auto_hibern8_timer(struct ufs_hba *hba, u32 delay)

1
drivers/scsi/ufs/ufshcd.h
View file

@ -431,6 +431,7 @@ struct ufs_clk_gating {
struct device_attribute enable_attr;
bool is_enabled;
int active_reqs;
struct workqueue_struct *ungating_workq;
};
/* Hibern8 state */