scsi: ufs: Add clock ungating to a separate workqueue
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>
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2 changed files with 9 additions and 1 deletions
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@ -1344,7 +1344,8 @@ start:
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hba->clk_gating.state = REQ_CLKS_ON;
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trace_ufshcd_clk_gating(dev_name(hba->dev),
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hba->clk_gating.state);
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schedule_work(&hba->clk_gating.ungate_work);
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queue_work(hba->clk_gating.ungating_workq,
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&hba->clk_gating.ungate_work);
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/*
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* fall through to check if we should wait for this
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* work to be done or not.
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@ -1617,6 +1618,7 @@ static enum hrtimer_restart ufshcd_clkgate_hrtimer_handler(
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static void ufshcd_init_clk_gating(struct ufs_hba *hba)
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{
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struct ufs_clk_gating *gating = &hba->clk_gating;
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char wq_name[sizeof("ufs_clk_ungating_00")];
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hba->clk_gating.state = CLKS_ON;
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@ -1645,6 +1647,10 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba)
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hrtimer_init(&gating->gate_hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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gating->gate_hrtimer.function = ufshcd_clkgate_hrtimer_handler;
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snprintf(wq_name, ARRAY_SIZE(wq_name), "ufs_clk_ungating_%d",
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hba->host->host_no);
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hba->clk_gating.ungating_workq = create_singlethread_workqueue(wq_name);
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gating->is_enabled = true;
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gating->delay_ms_pwr_save = UFSHCD_CLK_GATING_DELAY_MS_PWR_SAVE;
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@ -1707,6 +1713,7 @@ static void ufshcd_exit_clk_gating(struct ufs_hba *hba)
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device_remove_file(hba->dev, &hba->clk_gating.enable_attr);
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ufshcd_cancel_gate_work(hba);
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cancel_work_sync(&hba->clk_gating.ungate_work);
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destroy_workqueue(hba->clk_gating.ungating_workq);
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}
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static void ufshcd_set_auto_hibern8_timer(struct ufs_hba *hba, u32 delay)
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@ -431,6 +431,7 @@ struct ufs_clk_gating {
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struct device_attribute enable_attr;
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bool is_enabled;
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int active_reqs;
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struct workqueue_struct *ungating_workq;
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};
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/* Hibern8 state */
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