[PATCH v2 4/4] scsi: ufs: Fix handling of lrbp->cmd

[Bart Van Assche <bvanassche@acm.org>]

From: Bart Van Assche <bvanassche@google.com>

ufshcd_queuecommand() may be called two times in a row for a SCSI
command before it is completed. Additionally, a single SCSI command may
be completed twice. Hence make the following changes:
- In the functions that submit a command, do not check the old value of
  lrbp->cmd nor clear lrbp->cmd in error paths.
- In ufshcd_release_scsi_cmd(), do not clear lrbp->cmd.

See also scsi_send_eh_cmnd().

This patch prevents that the following appears if a command times out:

WARNING: at drivers/ufs/core/ufshcd.c:2965 ufshcd_queuecommand+0x6f8/0x9a8
Call trace:
 ufshcd_queuecommand+0x6f8/0x9a8
 scsi_send_eh_cmnd+0x2c0/0x960
 scsi_eh_test_devices+0x100/0x314
 scsi_eh_ready_devs+0xd90/0x114c
 scsi_error_handler+0x2b4/0xb70
 kthread+0x16c/0x1e0

Fixes: 5a0b0cb9bee7 ("[SCSI] ufs: Add support for sending NOP OUT UPIU")
Signed-off-by: Bart Van Assche <bvanassche@google.com>
---
 drivers/ufs/core/ufshcd.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 6831eb1afc30..4f4c5ba66bac 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2952,7 +2952,6 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 		(hba->clk_gating.state != CLKS_ON));
 
 	lrbp = &hba->lrb[tag];
-	WARN_ON(lrbp->cmd);
 	lrbp->cmd = cmd;
 	lrbp->task_tag = tag;
 	lrbp->lun = ufshcd_scsi_to_upiu_lun(cmd->device->lun);
@@ -2968,7 +2967,6 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 
 	err = ufshcd_map_sg(hba, lrbp);
 	if (err) {
-		lrbp->cmd = NULL;
 		ufshcd_release(hba);
 		goto out;
 	}
@@ -5429,7 +5427,6 @@ static void ufshcd_release_scsi_cmd(struct ufs_hba *hba,
 	struct scsi_cmnd *cmd = lrbp->cmd;
 
 	scsi_dma_unmap(cmd);
-	lrbp->cmd = NULL;	/* Mark the command as completed. */
 	ufshcd_release(hba);
 	ufshcd_clk_scaling_update_busy(hba);
 }
@@ -7044,7 +7041,6 @@ static int ufshcd_issue_devman_upiu_cmd(struct ufs_hba *hba,
 	down_read(&hba->clk_scaling_lock);
 
 	lrbp = &hba->lrb[tag];
-	WARN_ON(lrbp->cmd);
 	lrbp->cmd = NULL;
 	lrbp->task_tag = tag;
 	lrbp->lun = 0;
@@ -7216,7 +7212,6 @@ int ufshcd_advanced_rpmb_req_handler(struct ufs_hba *hba, struct utp_upiu_req *r
 	down_read(&hba->clk_scaling_lock);
 
 	lrbp = &hba->lrb[tag];
-	WARN_ON(lrbp->cmd);
 	lrbp->cmd = NULL;
 	lrbp->task_tag = tag;
 	lrbp->lun = UFS_UPIU_RPMB_WLUN;