scsi: ufs: core: mcq: Fix the incorrect OCS value for the device command

In MCQ mode, when a device command uses a hardware queue shared with other
commands, a race condition may occur in the following scenario:

 1. A device command is completed in CQx with CQE entry "e".

 2. The interrupt handler copies the "cqe" pointer to "hba->dev_cmd.cqe"
    and completes "hba->dev_cmd.complete".

 3. The "ufshcd_wait_for_dev_cmd()" function is awakened and retrieves the
    OCS value from "hba->dev_cmd.cqe".

However, there is a possibility that the CQE entry "e" will be overwritten
by newly completed commands in CQx, resulting in an incorrect OCS value
being received by "ufshcd_wait_for_dev_cmd()".

To avoid this race condition, the OCS value should be immediately copied to
the struct "lrb" of the device command. Then "ufshcd_wait_for_dev_cmd()"
can retrieve the OCS value from the struct "lrb".

Fixes: 57b1c0ef89ac ("scsi: ufs: core: mcq: Add support to allocate multiple queues")
Suggested-by: Can Guo <quic_cang@quicinc.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Link: https://lore.kernel.org/r/20230610021553.1213-2-powen.kao@mediatek.com
Tested-by: Po-Wen Kao <powen.kao@mediatek.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index add9ec1..ee4229c 100644 (file)
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -3086,7 +3086,7 @@ retry:
                 * not trigger any race conditions.
                 */
                hba->dev_cmd.complete = NULL;
-               err = ufshcd_get_tr_ocs(lrbp, hba->dev_cmd.cqe);
+               err = ufshcd_get_tr_ocs(lrbp, NULL);
                if (!err)
                        err = ufshcd_dev_cmd_completion(hba, lrbp);
        } else {
@@ -3182,7 +3182,6 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba,
                goto out;
 
        hba->dev_cmd.complete = &wait;
-       hba->dev_cmd.cqe = NULL;
 
        ufshcd_add_query_upiu_trace(hba, UFS_QUERY_SEND, lrbp->ucd_req_ptr);
 
@@ -5431,6 +5430,7 @@ void ufshcd_compl_one_cqe(struct ufs_hba *hba, int task_tag,
 {
        struct ufshcd_lrb *lrbp;
        struct scsi_cmnd *cmd;
+       enum utp_ocs ocs;
 
        lrbp = &hba->lrb[task_tag];
        lrbp->compl_time_stamp = ktime_get();
@@ -5446,7 +5446,11 @@ void ufshcd_compl_one_cqe(struct ufs_hba *hba, int task_tag,
        } else if (lrbp->command_type == UTP_CMD_TYPE_DEV_MANAGE ||
                   lrbp->command_type == UTP_CMD_TYPE_UFS_STORAGE) {
                if (hba->dev_cmd.complete) {
-                       hba->dev_cmd.cqe = cqe;
+                       if (cqe) {
+                               ocs = le32_to_cpu(cqe->status) & MASK_OCS;
+                               lrbp->utr_descriptor_ptr->header.dword_2 =
+                                       cpu_to_le32(ocs);
+                       }
                        complete(hba->dev_cmd.complete);
                        ufshcd_clk_scaling_update_busy(hba);
                }

diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index d65c9d0..92f073b 100644 (file)
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -225,7 +225,6 @@ struct ufs_dev_cmd {
        struct mutex lock;
        struct completion *complete;
        struct ufs_query query;
-       struct cq_entry *cqe;
 };
 
 /**