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

commit c63d6099a7959ecc919b2549dc6b71f53521f819 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 19f82069c68acc72fd04b639c289b98f9dd543be..bc7f8d634c805fdcc8ec92f300f33c327e975976 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -595,6 +595,11 @@ 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);