From: Bart Van Assche <bvanassche@google.com>
Date: Fri, 1 Oct 2021 11:20:15 -0700
Subject: scsi: ufs: core: Stop clearing UNIT ATTENTIONS
Git-commit: edc0596cc04bf0ac3a69c66e994d3ff8b650ff71
Patch-mainline: v5.16-rc1
References: git-fixes

Commit aa53f580e67b ("scsi: ufs: Minor adjustments to error handling")
introduced a ufshcd_clear_ua_wluns() call in
ufshcd_err_handling_unprepare(). As explained in detail by Adrian Hunter,
this can trigger a deadlock. Avoid that deadlock by removing the code that
clears the unit attention. This is safe because the only software that
relies on clearing unit attentions is the Android Trusty software and
because support for handling unit attentions has been added in the Trusty
software.

See also https://lore.kernel.org/linux-scsi/20210930124224.114031-2-adrian.hunter@intel.com/

Note that "scsi: ufs: Retry START_STOP on UNIT_ATTENTION" is a prerequisite
for this commit.

[lduncan: refreshed to apply]

Link: https://lore.kernel.org/r/20211001182015.1347587-3-jaegeuk@kernel.org
Fixes: aa53f580e67b ("scsi: ufs: Minor adjustments to error handling")
Cc: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Bart Van Assche <bvanassche@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Lee Duncan <lduncan@suse.com>
---
 drivers/scsi/ufs/ufshcd.c |  160 ----------------------------------------------
 drivers/scsi/ufs/ufshcd.h |   14 ----
 2 files changed, 1 insertion(+), 173 deletions(-)

--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -229,7 +229,6 @@ static int ufshcd_reset_and_restore(stru
 static int ufshcd_eh_host_reset_handler(struct scsi_cmnd *cmd);
 static int ufshcd_clear_tm_cmd(struct ufs_hba *hba, int tag);
 static void ufshcd_hba_exit(struct ufs_hba *hba);
-static int ufshcd_clear_ua_wluns(struct ufs_hba *hba);
 static int ufshcd_probe_hba(struct ufs_hba *hba, bool init_dev_params);
 static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on);
 static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba);
@@ -4100,8 +4099,6 @@ int ufshcd_link_recovery(struct ufs_hba
 	if (ret)
 		dev_err(hba->dev, "%s: link recovery failed, err %d",
 			__func__, ret);
-	else
-		ufshcd_clear_ua_wluns(hba);
 
 	return ret;
 }
@@ -5953,7 +5950,6 @@ static void ufshcd_err_handling_unprepar
 	ufshcd_release(hba);
 	if (ufshcd_is_clkscaling_supported(hba))
 		ufshcd_clk_scaling_suspend(hba, false);
-	ufshcd_clear_ua_wluns(hba);
 	ufshcd_rpm_put(hba);
 }
 
@@ -7860,8 +7856,6 @@ static int ufshcd_add_lus(struct ufs_hba
 	if (ret)
 		goto out;
 
-	ufshcd_clear_ua_wluns(hba);
-
 	/* Initialize devfreq after UFS device is detected */
 	if (ufshcd_is_clkscaling_supported(hba)) {
 		memcpy(&hba->clk_scaling.saved_pwr_info.info,
@@ -7886,63 +7880,6 @@ out:
 	return ret;
 }
 
-static int
-ufshcd_send_request_sense(struct ufs_hba *hba, struct scsi_device *sdp);
-
-static int ufshcd_clear_ua_wlun(struct ufs_hba *hba, u8 wlun)
-{
-	struct scsi_device *sdp;
-	unsigned long flags;
-	int ret = 0;
-
-	spin_lock_irqsave(hba->host->host_lock, flags);
-	if (wlun == UFS_UPIU_UFS_DEVICE_WLUN)
-		sdp = hba->sdev_ufs_device;
-	else if (wlun == UFS_UPIU_RPMB_WLUN)
-		sdp = hba->sdev_rpmb;
-	else
-		BUG();
-	if (sdp) {
-		ret = scsi_device_get(sdp);
-		if (!ret && !scsi_device_online(sdp)) {
-			ret = -ENODEV;
-			scsi_device_put(sdp);
-		}
-	} else {
-		ret = -ENODEV;
-	}
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
-	if (ret)
-		goto out_err;
-
-	ret = ufshcd_send_request_sense(hba, sdp);
-	scsi_device_put(sdp);
-out_err:
-	if (ret)
-		dev_err(hba->dev, "%s: UAC clear LU=%x ret = %d\n",
-				__func__, wlun, ret);
-	return ret;
-}
-
-static int ufshcd_clear_ua_wluns(struct ufs_hba *hba)
-{
-	int ret = 0;
-
-	if (!hba->wlun_dev_clr_ua)
-		goto out;
-
-	ret = ufshcd_clear_ua_wlun(hba, UFS_UPIU_UFS_DEVICE_WLUN);
-	if (!ret)
-		ret = ufshcd_clear_ua_wlun(hba, UFS_UPIU_RPMB_WLUN);
-	if (!ret)
-		hba->wlun_dev_clr_ua = false;
-out:
-	if (ret)
-		dev_err(hba->dev, "%s: Failed to clear UAC WLUNS ret = %d\n",
-				__func__, ret);
-	return ret;
-}
-
 /**
  * ufshcd_probe_hba - probe hba to detect device and initialize
  * @hba: per-adapter instance
@@ -7993,8 +7930,6 @@ static int ufshcd_probe_hba(struct ufs_h
 	/* UFS device is also active now */
 	ufshcd_set_ufs_dev_active(hba);
 	ufshcd_force_reset_auto_bkops(hba);
-	hba->wlun_dev_clr_ua = true;
-	hba->wlun_rpmb_clr_ua = true;
 
 	/* Gear up to HS gear if supported */
 	if (hba->max_pwr_info.is_valid) {
@@ -8510,35 +8445,6 @@ static void ufshcd_hba_exit(struct ufs_h
 	}
 }
 
-static int
-ufshcd_send_request_sense(struct ufs_hba *hba, struct scsi_device *sdp)
-{
-	unsigned char cmd[6] = {REQUEST_SENSE,
-				0,
-				0,
-				0,
-				UFS_SENSE_SIZE,
-				0};
-	char *buffer;
-	int ret;
-
-	buffer = kzalloc(UFS_SENSE_SIZE, GFP_KERNEL);
-	if (!buffer) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	ret = scsi_execute(sdp, cmd, DMA_FROM_DEVICE, buffer,
-			UFS_SENSE_SIZE, NULL, NULL,
-			msecs_to_jiffies(1000), 3, 0, RQF_PM, NULL);
-	if (ret)
-		pr_err("%s: failed with err %d\n", __func__, ret);
-
-	kfree(buffer);
-out:
-	return ret;
-}
-
 /**
  * ufshcd_set_dev_pwr_mode - sends START STOP UNIT command to set device
  *			     power mode
@@ -8580,8 +8486,6 @@ static int ufshcd_set_dev_pwr_mode(struc
 	 * handling context.
 	 */
 	hba->host->eh_noresume = 1;
-	if (hba->wlun_dev_clr_ua)
-		ufshcd_clear_ua_wlun(hba, UFS_UPIU_UFS_DEVICE_WLUN);
 
 	cmd[4] = pwr_mode << 4;
 
@@ -9643,10 +9547,6 @@ void ufshcd_resume_complete(struct devic
 		ufshcd_rpm_put(hba);
 		hba->complete_put = false;
 	}
-	if (hba->rpmb_complete_put) {
-		ufshcd_rpmb_rpm_put(hba);
-		hba->rpmb_complete_put = false;
-	}
 }
 EXPORT_SYMBOL_GPL(ufshcd_resume_complete);
 
@@ -9669,10 +9569,6 @@ int ufshcd_suspend_prepare(struct device
 		}
 		hba->complete_put = true;
 	}
-	if (hba->sdev_rpmb) {
-		ufshcd_rpmb_rpm_get_sync(hba);
-		hba->rpmb_complete_put = true;
-	}
 	return 0;
 }
 EXPORT_SYMBOL_GPL(ufshcd_suspend_prepare);
@@ -9741,49 +9637,6 @@ static struct scsi_driver ufs_dev_wlun_t
 	},
 };
 
-static int ufshcd_rpmb_probe(struct device *dev)
-{
-	return is_rpmb_wlun(to_scsi_device(dev)) ? 0 : -ENODEV;
-}
-
-static inline int ufshcd_clear_rpmb_uac(struct ufs_hba *hba)
-{
-	int ret = 0;
-
-	if (!hba->wlun_rpmb_clr_ua)
-		return 0;
-	ret = ufshcd_clear_ua_wlun(hba, UFS_UPIU_RPMB_WLUN);
-	if (!ret)
-		hba->wlun_rpmb_clr_ua = 0;
-	return ret;
-}
-
-#ifdef CONFIG_PM
-static int ufshcd_rpmb_resume(struct device *dev)
-{
-	struct ufs_hba *hba = wlun_dev_to_hba(dev);
-
-	if (hba->sdev_rpmb)
-		ufshcd_clear_rpmb_uac(hba);
-	return 0;
-}
-#endif
-
-static const struct dev_pm_ops ufs_rpmb_pm_ops = {
-	SET_RUNTIME_PM_OPS(NULL, ufshcd_rpmb_resume, NULL)
-	SET_SYSTEM_SLEEP_PM_OPS(NULL, ufshcd_rpmb_resume)
-};
-
-/* ufs_rpmb_wlun_template - Describes UFS RPMB WLUN. Used only to send UAC. */
-static struct scsi_driver ufs_rpmb_wlun_template = {
-	.gendrv = {
-		.name = "ufs_rpmb_wlun",
-		.owner = THIS_MODULE,
-		.probe = ufshcd_rpmb_probe,
-		.pm = &ufs_rpmb_pm_ops,
-	},
-};
-
 static int __init ufshcd_core_init(void)
 {
 	int ret;
@@ -9792,24 +9645,13 @@ static int __init ufshcd_core_init(void)
 
 	ret = scsi_register_driver(&ufs_dev_wlun_template.gendrv);
 	if (ret)
-		goto debugfs_exit;
-
-	ret = scsi_register_driver(&ufs_rpmb_wlun_template.gendrv);
-	if (ret)
-		goto unregister;
-
-	return ret;
-unregister:
-	scsi_unregister_driver(&ufs_dev_wlun_template.gendrv);
-debugfs_exit:
-	ufs_debugfs_exit();
+		ufs_debugfs_exit();
 	return ret;
 }
 
 static void __exit ufshcd_core_exit(void)
 {
 	ufs_debugfs_exit();
-	scsi_unregister_driver(&ufs_rpmb_wlun_template.gendrv);
 	scsi_unregister_driver(&ufs_dev_wlun_template.gendrv);
 }
 
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -823,9 +823,6 @@ struct ufs_hba {
 	struct ufs_vreg_info vreg_info;
 	struct list_head clk_list_head;
 
-	bool wlun_dev_clr_ua;
-	bool wlun_rpmb_clr_ua;
-
 	/* Number of requests aborts */
 	int req_abort_count;
 
@@ -868,7 +865,6 @@ struct ufs_hba {
 #endif
 	u32 luns_avail;
 	bool complete_put;
-	bool rpmb_complete_put;
 };
 
 /* Returns true if clocks can be gated. Otherwise false */
@@ -1343,14 +1339,4 @@ static inline int ufshcd_rpm_put(struct
 	return pm_runtime_put(&hba->sdev_ufs_device->sdev_gendev);
 }
 
-static inline int ufshcd_rpmb_rpm_get_sync(struct ufs_hba *hba)
-{
-	return pm_runtime_get_sync(&hba->sdev_rpmb->sdev_gendev);
-}
-
-static inline int ufshcd_rpmb_rpm_put(struct ufs_hba *hba)
-{
-	return pm_runtime_put(&hba->sdev_rpmb->sdev_gendev);
-}
-
 #endif /* End of Header */