Commit 7a7e66c6 authored by Can Guo's avatar Can Guo Committed by Martin K. Petersen
Browse files

scsi: ufs: Fix a race condition between ufshcd_abort() and eh_work() 

In current task abort routine, if task abort happens to the device W-LUN,
the code directly jumps to ufshcd_eh_host_reset_handler() to perform a full
reset and restore then returns FAIL or SUCCESS. Commands sent to the device
W-LUN are most likely the SSU cmds sent during UFS PM operations. If such
SSU cmd enters task abort routine when ufshcd_eh_host_reset_handler()
flushes eh_work, it will get stuck there since err_handler is serialized
with PM operations.

In order to unblock above call path, we merely clean up the lrb taken by
this cmd, queue the eh_work and return SUCCESS. Once the cmd is aborted,
the PM operation which sends out the cmd just errors out, then err_handler
shall be able to proceed with the full reset and restore.

In this scenario, the cmd is aborted even before it is actually cleared by
HW, set the lrb->in_use flag to prevent subsequent cmds, including SCSI
cmds and dev cmds, from taking the lrb released from abort. The flag shall
evetually be cleared in __ufshcd_transfer_req_compl() invoked by the full
reset and restore from err_handler.

[mkp: conflict with event logging series]

Link: https://lore.kernel.org/r/1606910644-21185-3-git-send-email-cang@codeaurora.org


Reviewed-by: default avatarAsutosh Das <asutoshd@codeaurora.org>
Reviewed-by: default avatarStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: default avatarCan Guo <cang@codeaurora.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 88a92d6a

drivers/scsi/ufs/ufshcd.c

+49 −15
Original line number Diff line number Diff line
@@ -2558,6 +2558,14 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd) 
		(hba->clk_gating.state != CLKS_ON));



	lrbp = &hba->lrb[tag];

	if (unlikely(lrbp->in_use)) {

		if (hba->pm_op_in_progress)

			set_host_byte(cmd, DID_BAD_TARGET);

		else

			err = SCSI_MLQUEUE_HOST_BUSY;

		ufshcd_release(hba);

		goto out;

	}



	WARN_ON(lrbp->cmd);

	lrbp->cmd = cmd;
@@ -2800,6 +2808,11 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba, 


	init_completion(&wait);

	lrbp = &hba->lrb[tag];

	if (unlikely(lrbp->in_use)) {

		err = -EBUSY;

		goto out;

	}



	WARN_ON(lrbp->cmd);

	err = ufshcd_compose_dev_cmd(hba, lrbp, cmd_type, tag);

	if (unlikely(err))
@@ -2816,6 +2829,7 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba, 


	err = ufshcd_wait_for_dev_cmd(hba, lrbp, timeout);



out:

	ufshcd_add_query_upiu_trace(hba, tag,

			err ? "query_complete_err" : "query_complete");
@@ -4980,9 +4994,11 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba, 
	struct scsi_cmnd *cmd;

	int result;

	int index;

	bool update_scaling = false;



	for_each_set_bit(index, &completed_reqs, hba->nutrs) {

		lrbp = &hba->lrb[index];

		lrbp->in_use = false;

		lrbp->compl_time_stamp = ktime_get();

		cmd = lrbp->cmd;

		if (cmd) {
@@ -4995,15 +5011,17 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba, 
			/* Do not touch lrbp after scsi done */

			cmd->scsi_done(cmd);

			__ufshcd_release(hba);

			update_scaling = true;

		} else if (lrbp->command_type == UTP_CMD_TYPE_DEV_MANAGE ||

			lrbp->command_type == UTP_CMD_TYPE_UFS_STORAGE) {

			if (hba->dev_cmd.complete) {

				ufshcd_add_command_trace(hba, index,

						"dev_complete");

				complete(hba->dev_cmd.complete);

				update_scaling = true;

			}

		}

		if (ufshcd_is_clkscaling_supported(hba))

		if (ufshcd_is_clkscaling_supported(hba) && update_scaling)

			hba->clk_scaling.active_reqs--;

	}
@@ -6426,8 +6444,12 @@ static int ufshcd_issue_devman_upiu_cmd(struct ufs_hba *hba, 


	init_completion(&wait);

	lrbp = &hba->lrb[tag];

	WARN_ON(lrbp->cmd);

	if (unlikely(lrbp->in_use)) {

		err = -EBUSY;

		goto out;

	}



	WARN_ON(lrbp->cmd);

	lrbp->cmd = NULL;

	lrbp->sense_bufflen = 0;

	lrbp->sense_buffer = NULL;
@@ -6499,6 +6521,7 @@ static int ufshcd_issue_devman_upiu_cmd(struct ufs_hba *hba, 
		}

	}



out:

	blk_put_request(req);

out_unlock:

	up_read(&hba->clk_scaling_lock);
@@ -6749,18 +6772,6 @@ static int ufshcd_abort(struct scsi_cmnd *cmd) 
		BUG();

	}



	/*

	 * Task abort to the device W-LUN is illegal. When this command

	 * will fail, due to spec violation, scsi err handling next step

	 * will be to send LU reset which, again, is a spec violation.

	 * To avoid these unnecessary/illegal step we skip to the last error

	 * handling stage: reset and restore.

	 */

	if (lrbp->lun == UFS_UPIU_UFS_DEVICE_WLUN) {

		ufshcd_update_evt_hist(hba, UFS_EVT_ABORT, lrbp->lun);

		return ufshcd_eh_host_reset_handler(cmd);

	}



	ufshcd_hold(hba, false);

	reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);

	/* If command is already aborted/completed, return SUCCESS */
@@ -6781,7 +6792,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd) 
	 * to reduce repeated printouts. For other aborted requests only print

	 * basic details.

	 */

	scsi_print_command(hba->lrb[tag].cmd);

	scsi_print_command(cmd);

	if (!hba->req_abort_count) {

		ufshcd_update_evt_hist(hba, UFS_EVT_ABORT, tag);

		ufshcd_print_evt_hist(hba);
@@ -6800,6 +6811,29 @@ static int ufshcd_abort(struct scsi_cmnd *cmd) 
		goto cleanup;

	}



	/*

	 * Task abort to the device W-LUN is illegal. When this command

	 * will fail, due to spec violation, scsi err handling next step

	 * will be to send LU reset which, again, is a spec violation.

	 * To avoid these unnecessary/illegal steps, first we clean up

	 * the lrb taken by this cmd and mark the lrb as in_use, then

	 * queue the eh_work and bail.

	 */

	if (lrbp->lun == UFS_UPIU_UFS_DEVICE_WLUN) {

		ufshcd_update_evt_hist(hba, UFS_EVT_ABORT, lrbp->lun);

		spin_lock_irqsave(host->host_lock, flags);

		if (lrbp->cmd) {

			__ufshcd_transfer_req_compl(hba, (1UL << tag));

			__set_bit(tag, &hba->outstanding_reqs);

			lrbp->in_use = true;

			hba->force_reset = true;

			ufshcd_schedule_eh_work(hba);

		}



		spin_unlock_irqrestore(host->host_lock, flags);

		goto out;

	}



	/* Skip task abort in case previous aborts failed and report failure */

	if (lrbp->req_abort_skip)

		err = -EIO;

drivers/scsi/ufs/ufshcd.h

+2 −0
Original line number Diff line number Diff line
@@ -193,6 +193,7 @@ struct ufs_pm_lvl_states { 
 * @crypto_key_slot: the key slot to use for inline crypto (-1 if none)

 * @data_unit_num: the data unit number for the first block for inline crypto

 * @req_abort_skip: skip request abort task flag

 * @in_use: indicates that this lrb is still in use

 */

struct ufshcd_lrb {

	struct utp_transfer_req_desc *utr_descriptor_ptr;
@@ -222,6 +223,7 @@ struct ufshcd_lrb { 
#endif



	bool req_abort_skip;

	bool in_use;

};



/**