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_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 <vviswana@codeaurora.org> Signed-off-by: Can Guo <cang@codeaurora.org> Signed-off-by: Asutosh Das <asutoshd@codeaurora.org> Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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@ -1532,7 +1532,8 @@ 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.clk_gating_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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@ -1718,6 +1719,8 @@ out:
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static void ufshcd_init_clk_gating(struct ufs_hba *hba)
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{
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char wq_name[sizeof("ufs_clk_gating_00")];
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if (!ufshcd_is_clkgating_allowed(hba))
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return;
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@ -1725,6 +1728,11 @@ static void ufshcd_init_clk_gating(struct ufs_hba *hba)
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INIT_DELAYED_WORK(&hba->clk_gating.gate_work, ufshcd_gate_work);
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INIT_WORK(&hba->clk_gating.ungate_work, ufshcd_ungate_work);
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snprintf(wq_name, ARRAY_SIZE(wq_name), "ufs_clk_gating_%d",
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hba->host->host_no);
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hba->clk_gating.clk_gating_workq = alloc_ordered_workqueue(wq_name,
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WQ_MEM_RECLAIM);
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hba->clk_gating.is_enabled = true;
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hba->clk_gating.delay_attr.show = ufshcd_clkgate_delay_show;
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@ -1752,6 +1760,7 @@ 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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cancel_work_sync(&hba->clk_gating.ungate_work);
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cancel_delayed_work_sync(&hba->clk_gating.gate_work);
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destroy_workqueue(hba->clk_gating.clk_gating_workq);
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}
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/* Must be called with host lock acquired */
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@ -362,6 +362,7 @@ 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 *clk_gating_workq;
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};
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struct ufs_saved_pwr_info {
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