[PATCH 6.4 483/800] scsi: ufs: core: mcq: Fix the incorrect OCS value for the device command

Greg Kroah-Hartman
2023-07-16T20:15:29Z

From: Stanley Chu <stanley.chu@mediatek.com>

[ Upstream commit 0fef6bb730c490fcdc4347dbd21646d3ffe62cf5 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/ufs/core/ufshcd.c | 10 +++++++---
include/ufs/ufshcd.h | 1 -
2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 41f383b588865..6d8ef80d9cbc4 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -3097,7 +3097,7 @@ static int ufshcd_wait_for_dev_cmd(struct ufs_hba *hba,
* 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 {
@@ -3184,7 +3184,6 @@ 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);

@@ -5435,6 +5434,7 @@ 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();
@@ -5450,7 +5450,11 @@ 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 df1d04f7a5424..8eecbb3766158 100644
--- 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;
};

/**
--
2.39.2