Messages in this thread | | | Date | Thu, 07 Jan 2021 15:03:07 +0800 | From | Can Guo <> | Subject | Re: [PATCH v3 2/2] scsi: ufs: handle LINERESET with correct tm_cmd |
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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@google.com> >> > >> > 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@kernel.org> >> > --- >> > 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,
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