scsi: ufs: Fix possible infinite loop in ufshcd_hold

In ufshcd_suspend(), after clk-gating is suspended and link is set
as Hibern8 state, ufshcd_hold() is still possibly invoked before
ufshcd_suspend() returns. For example, MediaTek's suspend vops may
issue UIC commands which would call ufshcd_hold() during the command
issuing flow.

Now if UFSHCD_CAP_HIBERN8_WITH_CLK_GATING capability is enabled,
then ufshcd_hold() may enter infinite loops because there is no
clk-ungating work scheduled or pending. In this case, ufshcd_hold()
shall just bypass, and keep the link as Hibern8 state.

Link: https://lore.kernel.org/r/20200809050734.18740-1-stanley.chu@mediatek.com
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Co-developed-by: Andy Teng <andy.teng@mediatek.com>
Signed-off-by: Andy Teng <andy.teng@mediatek.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 30762228423981253c7cf4908feca8d99d51543b..b4f948027b3e6bcf4742ff1174cd02fddc91aa2d 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1561,6 +1561,7 @@ unblock_reqs:
 int ufshcd_hold(struct ufs_hba *hba, bool async)
 {
        int rc = 0;
+       bool flush_result;
        unsigned long flags;
 
        if (!ufshcd_is_clkgating_allowed(hba))
@@ -1592,7 +1593,9 @@ start:
                                break;
                        }
                        spin_unlock_irqrestore(hba->host->host_lock, flags);
-                       flush_work(&hba->clk_gating.ungate_work);
+                       flush_result = flush_work(&hba->clk_gating.ungate_work);
+                       if (hba->clk_gating.is_suspended && !flush_result)
+                               goto out;
                        spin_lock_irqsave(hba->host->host_lock, flags);
                        goto start;
                }