Re: [PATCH v3 2/2] scsi: ufs: handle LINERESET with correct tm_cmd
From: Can Guo
Date: Thu Jan 07 2021 - 02:04:12 EST
On 2021-01-07 14:51, Jaegeuk Kim wrote:
On 01/07, Can Guo wrote:
On 2021-01-07 05:41, Jaegeuk Kim wrote:
> From: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
>
> This fixes a warning caused by wrong reserve tag usage in
> __ufshcd_issue_tm_cmd.
>
> WARNING: CPU: 7 PID: 7 at block/blk-core.c:630 blk_get_request+0x68/0x70
> WARNING: CPU: 4 PID: 157 at block/blk-mq-tag.c:82
> blk_mq_get_tag+0x438/0x46c
>
> And, in ufshcd_err_handler(), we can avoid to send tm_cmd before
> aborting
> outstanding commands by waiting a bit for IO completion like this.
>
> __ufshcd_issue_tm_cmd: task management cmd 0x80 timed-out
>
Would you mind add a Fixes tag?
Ok.
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
> drivers/scsi/ufs/ufshcd.c | 36 ++++++++++++++++++++++++++++++++----
> 1 file changed, 32 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 1678cec08b51..47fc8da3cbf9 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -44,6 +44,9 @@
> /* Query request timeout */
> #define QUERY_REQ_TIMEOUT 1500 /* 1.5 seconds */
>
> +/* LINERESET TIME OUT */
> +#define LINERESET_IO_TIMEOUT_MS (30000) /* 30 sec */
> +
> /* Task management command timeout */
> #define TM_CMD_TIMEOUT 100 /* msecs */
>
> @@ -5899,6 +5902,8 @@ static void ufshcd_err_handler(struct work_struct
> *work)
> * check if power mode restore is needed.
> */
> if (hba->saved_uic_err & UFSHCD_UIC_PA_GENERIC_ERROR) {
> + ktime_t start = ktime_get();
> +
> hba->saved_uic_err &= ~UFSHCD_UIC_PA_GENERIC_ERROR;
> if (!hba->saved_uic_err)
> hba->saved_err &= ~UIC_ERROR;
> @@ -5906,6 +5911,20 @@ static void ufshcd_err_handler(struct work_struct
> *work)
> if (ufshcd_is_pwr_mode_restore_needed(hba))
> needs_restore = true;
> spin_lock_irqsave(hba->host->host_lock, flags);
> + /* Wait for IO completion to avoid aborting IOs */
> + while (hba->outstanding_reqs) {
> + ufshcd_complete_requests(hba);
> + spin_unlock_irqrestore(hba->host->host_lock, flags);
> + schedule();
> + spin_lock_irqsave(hba->host->host_lock, flags);
> + if (ktime_to_ms(ktime_sub(ktime_get(), start)) >
> + LINERESET_IO_TIMEOUT_MS) {
> + dev_err(hba->dev, "%s: timeout, outstanding=0x%lx\n",
> + __func__, hba->outstanding_reqs);
> + break;
> + }
> + }
> +
> if (!hba->saved_err && !needs_restore)
> goto skip_err_handling;
> }
> @@ -6302,9 +6321,13 @@ static irqreturn_t ufshcd_intr(int irq, void
> *__hba)
> intr_status = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
> }
>
> - if (enabled_intr_status && retval == IRQ_NONE) {
> - dev_err(hba->dev, "%s: Unhandled interrupt 0x%08x\n",
> - __func__, intr_status);
> + if (enabled_intr_status && retval == IRQ_NONE &&
> + !ufshcd_eh_in_progress(hba)) {
> + dev_err(hba->dev, "%s: Unhandled interrupt 0x%08x (0x%08x,
> 0x%08x)\n",
> + __func__,
> + intr_status,
> + hba->ufs_stats.last_intr_status,
> + enabled_intr_status);
> ufshcd_dump_regs(hba, 0, UFSHCI_REG_SPACE_SIZE, "host_regs: ");
> }
>
> @@ -6348,7 +6371,11 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba
> *hba,
> * Even though we use wait_event() which sleeps indefinitely,
> * the maximum wait time is bounded by %TM_CMD_TIMEOUT.
> */
> - req = blk_get_request(q, REQ_OP_DRV_OUT, BLK_MQ_REQ_RESERVED);
> + req = blk_get_request(q, REQ_OP_DRV_OUT, BLK_MQ_REQ_RESERVED |
> + BLK_MQ_REQ_NOWAIT);
Sorry that I didn't pay much attention to this part of code before.
May I know why must we use the BLK_MQ_REQ_RESERVED flag?
What I understood is the reserved tag is used when aborting outstanding
IOs when all the 32 tags were used.
No, the tm requests and I/O requests are on two different tag sets:
tm requests come from hba->tmf_tag_set, while I/O requests come from
hba->shost->tag_set. Meaning they don't share tags with each other.
Thanks,
Can Guo.
> + if (IS_ERR(req))
> + return PTR_ERR(req);
> +
> req->end_io_data = &wait;
> free_slot = req->tag;
> WARN_ON_ONCE(free_slot < 0 || free_slot >= hba->nutmrs);
> @@ -9355,6 +9382,7 @@ int ufshcd_init(struct ufs_hba *hba, void
> __iomem *mmio_base, unsigned int irq)
>
> hba->tmf_tag_set = (struct blk_mq_tag_set) {
> .nr_hw_queues = 1,
> + .reserved_tags = 1,
If we give reserved_tags as 1 and always ask for a tm requst with
BLK_MQ_REQ_RESERVED flag set, then the tag shall only be allocated
from the reserved sbitmap_queue, whose depth is set to 1 here.
UFS supports tm queue depth as 8, but here is allowing only one tm
req at a time. Why? Please correct me if my understanding is wrong.
I couldn't find tm can be issued in parallel, so thought it was issued
one at a time. If we set 8, then we can use 24 for IOs, IIUC.
Please correct me as well. I'm still trying to understand the flow.
UFS allows a queue depth as 8, which means it support sending multiple
tm requests at the same time. You can check commit 69a6c269c097d780a2 -
before this change, we used to use below func to allocate tags for
tm reqs, which can tell you the true story.
So I am thinking why don't we just we remove the BLK_MQ_REQ_RESERVED
flag?
Removing it can also fix the warning I suppose. What do you think?
-static bool ufshcd_get_tm_free_slot(struct ufs_hba *hba, int
*free_slot)
-{
- int tag;
- bool ret = false;
-
- if (!free_slot)
- goto out;
-
- do {
- tag = find_first_zero_bit(&hba->tm_slots_in_use,
hba->nutmrs);
- if (tag >= hba->nutmrs)
- goto out;
- } while (test_and_set_bit_lock(tag, &hba->tm_slots_in_use));
-
- *free_slot = tag;
- ret = true;
-out:
- return ret;
-}
Thanks,
Can Guo.
Thanks,
Can Guo.
> .queue_depth = hba->nutmrs,
> .ops = &ufshcd_tmf_ops,
> .flags = BLK_MQ_F_NO_SCHED,