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

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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: 57b1c0ef89 ("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>
This commit is contained in:
Stanley Chu 2023-06-10 10:15:51 +08:00 committed by Martin K. Petersen
parent e246514ae6
commit 0fef6bb730
2 changed files with 7 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/ufs/core/ufshcd.c
View File

@ -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);
}

1
include/ufs/ufshcd.h
View File

@ -225,7 +225,6 @@ struct ufs_dev_cmd {
struct mutex lock;
struct completion *complete;
struct ufs_query query;
struct cq_entry *cqe;
};
/**