Re: [PATCH v1 1/5] ufs: mcq: Add supporting functions for mcq abort

["Powen Kao (高伯文)" <Powen.Kao@mediatek.com>]

Hi Bao D.,

We have done some test based on your RFC v3 patches and an issue is
reported. 

   kworker/u16:4: BUG: scheduling while atomic:
   kworker/u16:4/5736/0x00000002
   kworker/u16:4: [name:core&]Preemption disabled at:
   kworker/u16:4: [<ffffffef97e33024>] ufshcd_mcq_sq_cleanup+0x9c/0x27c
   kworker/u16:4: CPU: 2 PID: 5736 Comm: kworker/u16:4 Tainted: G
   S      W  OE      
   kworker/u16:4: Workqueue: ufs_eh_wq_0 ufshcd_err_handler
   kworker/u16:4: Call trace:
   kworker/u16:4:  dump_backtrace+0x108/0x15c
   kworker/u16:4:  show_stack+0x20/0x30
   kworker/u16:4:  dump_stack_lvl+0x6c/0x8c
   kworker/u16:4:  dump_stack+0x20/0x44
   kworker/u16:4:  __schedule_bug+0xd4/0x100
   kworker/u16:4:  __schedule+0x660/0xa5c
   kworker/u16:4:  schedule+0x80/0xec
   kworker/u16:4:  schedule_hrtimeout_range_clock+0xa0/0x140
   kworker/u16:4:  schedule_hrtimeout_range+0x1c/0x30
   kworker/u16:4:  usleep_range_state+0x88/0xd8
   kworker/u16:4:  ufshcd_mcq_sq_cleanup+0x170/0x27c
   kworker/u16:4:  ufshcd_clear_cmds+0x78/0x184
   kworker/u16:4:  ufshcd_wait_for_dev_cmd+0x234/0x348
   kworker/u16:4:  ufshcd_exec_dev_cmd+0x220/0x298
   kworker/u16:4:  ufshcd_verify_dev_init+0x68/0x124
   kworker/u16:4:  ufshcd_probe_hba+0x390/0x9bc
   kworker/u16:4:  ufshcd_host_reset_and_restore+0x74/0x158
   kworker/u16:4:  ufshcd_reset_and_restore+0x70/0x31c
   kworker/u16:4:  ufshcd_err_handler+0xad4/0xe58
   kworker/u16:4:  process_one_work+0x214/0x5b8
   kworker/u16:4:  worker_thread+0x2d4/0x448
   kworker/u16:4:  kthread+0x110/0x1e0
   kworker/u16:4:  ret_from_fork+0x10/0x20
   kworker/u16:4: ------------[ cut here ]------------


On Wed, 2023-03-29 at 03:01 -0700, Bao D. Nguyen wrote:

> +/**
> + * ufshcd_mcq_sq_cleanup - Clean up Submission Queue resources
> + * associated with the pending command.
> + * @hba - per adapter instance.
> + * @task_tag - The command's task tag.
> + * @result - Result of the Clean up operation.
> + *
> + * Returns 0 and result on completion. Returns error code if
> + * the operation fails.
> + */
> +int ufshcd_mcq_sq_cleanup(struct ufs_hba *hba, int task_tag, int
> *result)
> +{
> +       struct ufshcd_lrb *lrbp = &hba->lrb[task_tag];
> +       struct scsi_cmnd *cmd = lrbp->cmd;
> +       struct ufs_hw_queue *hwq;
> +       void __iomem *reg, *opr_sqd_base;
> +       u32 nexus, i, val;
> +       int err;
> +
> +       if (task_tag != hba->nutrs - UFSHCD_NUM_RESERVED) {
> +               if (!cmd)
> +                       return FAILED;
> +               hwq = ufshcd_mcq_req_to_hwq(hba,
> scsi_cmd_to_rq(cmd));
> +       } else {
> +               hwq = hba->dev_cmd_queue;
> +       }
> +
> +       i = hwq->id;
> +
> +       spin_lock(&hwq->sq_lock);

As spin_lock() disable preemption

> +
> +       /* stop the SQ fetching before working on it */
> +       err = ufshcd_mcq_sq_stop(hba, hwq);
> +       if (err)
> +               goto unlock;
> +
> +       /* SQCTI = EXT_IID, IID, LUN, Task Tag */
> +       nexus = lrbp->lun << 8 | task_tag;
> +       opr_sqd_base = mcq_opr_base(hba, OPR_SQD, i);
> +       writel(nexus, opr_sqd_base + REG_SQCTI);
> +
> +       /* SQRTCy.ICU = 1 */
> +       writel(SQ_ICU, opr_sqd_base + REG_SQRTC);
> +
> +       /* Poll SQRTSy.CUS = 1. Return result from SQRTSy.RTC */
> +       reg = opr_sqd_base + REG_SQRTS;
> +       err = read_poll_timeout(readl, val, val & SQ_CUS, 20,
> +                               MCQ_POLL_US, false, reg);

read_poll_timeout() was ufshcd_mcq_poll_register() in last patch,
right? ufshcd_mcq_poll_register() calls usleep_range() causing KE as
reported above. Same issue seems to still exist as read_poll_timeout()
sleeps.

Skipping ufshcd_mcq_sq_cleanup() by returning FAILED directly to
trigger reset in ufshcd error handler successfully recover host.

BTW, is there maybe a change list between RFC v3 and this v1 patch? :)
Thanks

Po-Wen