scsi: ufs: Fix ufshcd_hold() caused scheduling while atomic

The async version of ufshcd_hold(async == true), which is only called in
queuecommand path as for now, is expected to work in atomic context, thus
it should not sleep or schedule out. When it runs into the condition that
clocks are ON but link is still in hibern8 state, it should bail out
without flushing the clock ungate work.

Fixes: f2a785ac2312 ("scsi: ufshcd: Fix race between clk scaling and ungate work")
Link: https://lore.kernel.org/r/1581392451-28743-6-git-send-email-cang@codeaurora.org
Reviewed-by: Hongwu Su <hongwus@codeaurora.org>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Can Guo <cang@codeaurora.org>
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 661ba37..1927074 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1518,6 +1518,11 @@ start:
                 */
                if (ufshcd_can_hibern8_during_gating(hba) &&
                    ufshcd_is_link_hibern8(hba)) {
+                       if (async) {
+                               rc = -EAGAIN;
+                               hba->clk_gating.active_reqs--;
+                               break;
+                       }
                        spin_unlock_irqrestore(hba->host->host_lock, flags);
                        flush_work(&hba->clk_gating.ungate_work);
                        spin_lock_irqsave(hba->host->host_lock, flags);