scsi: ufs: Fix a race condition in the tracing code

Starting execution of a command before tracing a command may cause the
completion handler to free data while it is being traced. Fix this race by
tracing a command before it is submitted.

Cc: Bean Huo <beanhuo@micron.com>
Cc: Can Guo <cang@codeaurora.org>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Stanley Chu <stanley.chu@mediatek.com>
Cc: Tomas Winkler <tomas.winkler@intel.com>
Link: https://lore.kernel.org/r/20191224220248.30138-5-bvanassche@acm.org
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 4bf6029..f8e5f2d 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1860,12 +1860,12 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag)
 {
        hba->lrb[task_tag].issue_time_stamp = ktime_get();
        hba->lrb[task_tag].compl_time_stamp = ktime_set(0, 0);
+       ufshcd_add_command_trace(hba, task_tag, "send");
        ufshcd_clk_scaling_start_busy(hba);
        __set_bit(task_tag, &hba->outstanding_reqs);
        ufshcd_writel(hba, 1 << task_tag, REG_UTP_TRANSFER_REQ_DOOR_BELL);
        /* Make sure that doorbell is committed immediately */
        wmb();
-       ufshcd_add_command_trace(hba, task_tag, "send");
 }
 
 /**