| Message ID | 1611136471-12295-1-git-send-email-cang@codeaurora.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | scsi: ufs: Fix some problems in task management request implementation | expand |
On 01/20, Can Guo wrote: > Current task management request send/compl implementation is broken, the > problems and fixes are listed as below: > > Problem: TMR completion timeout. ufshcd_tmc_handler() calls > blk_mq_tagset_busy_iter(fn == ufshcd_compl_tm()), but since > blk_mq_tagset_busy_iter() only iterates over all reserved tags and > started requests, so ufshcd_compl_tm() never gets a chance to run. > Fix: Call blk_mq_start_request() in __ufshcd_issue_tm_cmd(). > > Problem: Race condition in send/compl paths. ufshcd_compl_tm() looks for > all 0 bits in the REG_UTP_TASK_REQ_DOOR_BELL and call complete() > for each req who has the req->end_io_data set. There can be a race > condition btw tmc send/compl, because req->end_io_data is set, in > __ufshcd_issue_tm_cmd(), without host lock protection, so it is > possible that when ufshcd_compl_tm() checks the req->end_io_data, > req->end_io_data is set but the corresponding tag has not been set > in the REG_UTP_TASK_REQ_DOOR_BELL. Thus, ufshcd_tmc_handler() may > wrongly complete TMRs which have not been sent. > Fix: Protect req->end_io_data with host lock. And let ufshcd_compl_tm() > only handle those tm cmds which have been completed instead of > looking for 0 bits in the REG_UTP_TASK_REQ_DOOR_BELL. > > Problem: In __ufshcd_issue_tm_cmd(), it is not right to use hba->nutrs + > req->tag as the Task Tag in one TMR UPIU. > Fix: Directly use req->tag as Task Tag. > > Cc: Jaegeuk Kim <jaegeuk@kernel.org> > Signed-off-by: Can Guo <cang@codeaurora.org> > > --- > > This change is based on Jaegeuk's change - https://git.kernel.org/mkp/scsi/c/eeb1b55b6e25 > > --- > > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c > index fb07e3a..44d09509 100644 > --- a/drivers/scsi/ufs/ufshcd.c > +++ b/drivers/scsi/ufs/ufshcd.c > @@ -6252,7 +6252,7 @@ static irqreturn_t ufshcd_check_errors(struct ufs_hba *hba) > > struct ctm_info { > struct ufs_hba *hba; > - unsigned long pending; > + unsigned long completed; > unsigned int ncpl; > }; > > @@ -6261,13 +6261,13 @@ static bool ufshcd_compl_tm(struct request *req, void *priv, bool reserved) > struct ctm_info *const ci = priv; > struct completion *c; > > - WARN_ON_ONCE(reserved); > - if (test_bit(req->tag, &ci->pending)) > - return true; > - ci->ncpl++; > - c = req->end_io_data; > - if (c) > - complete(c); > + if (test_bit(req->tag, &ci->completed)) { > + __clear_bit(req->tag, &hba->outstanding_tasks); Is the below fixed in -next? __clear_bit(req->tag, &ci->hba->outstanding_tasks); > + ci->ncpl++; > + c = req->end_io_data; > + if (c) > + complete(c); > + } > return true; > } > > @@ -6283,11 +6283,19 @@ static irqreturn_t ufshcd_tmc_handler(struct ufs_hba *hba) > { > struct request_queue *q = hba->tmf_queue; > struct ctm_info ci = { > - .hba = hba, > - .pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL), > + .hba = hba, > + .ncpl = 0, > }; > + u32 tm_doorbell; > + unsigned long completed; > + > + tm_doorbell = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL); > + completed = tm_doorbell ^ hba->outstanding_tasks; > > - blk_mq_tagset_busy_iter(q->tag_set, ufshcd_compl_tm, &ci); > + if (completed) { > + ci.completed = completed; > + blk_mq_tagset_busy_iter(q->tag_set, ufshcd_compl_tm, &ci); > + } > return ci.ncpl ? IRQ_HANDLED : IRQ_NONE; > } > > @@ -6405,37 +6413,33 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba, > DECLARE_COMPLETION_ONSTACK(wait); > struct request *req; > unsigned long flags; > - int free_slot, task_tag, err; > + int task_tag, err; > > /* > - * Get free slot, sleep if slots are unavailable. > - * Even though we use wait_event() which sleeps indefinitely, > - * the maximum wait time is bounded by %TM_CMD_TIMEOUT. > + * blk_get_request() used here is only to get a free tag. > */ > req = blk_get_request(q, REQ_OP_DRV_OUT, 0); > 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); > ufshcd_hold(hba, false); > - > spin_lock_irqsave(host->host_lock, flags); > - task_tag = hba->nutrs + free_slot; > + req->end_io_data = &wait; > + blk_mq_start_request(req); > > + task_tag = req->tag; > treq->req_header.dword_0 |= cpu_to_be32(task_tag); > > - memcpy(hba->utmrdl_base_addr + free_slot, treq, sizeof(*treq)); > - ufshcd_vops_setup_task_mgmt(hba, free_slot, tm_function); > + memcpy(hba->utmrdl_base_addr + task_tag, treq, sizeof(*treq)); > + ufshcd_vops_setup_task_mgmt(hba, task_tag, tm_function); > > /* send command to the controller */ > - __set_bit(free_slot, &hba->outstanding_tasks); > + __set_bit(task_tag, &hba->outstanding_tasks); > > /* Make sure descriptors are ready before ringing the task doorbell */ > wmb(); > > - ufshcd_writel(hba, 1 << free_slot, REG_UTP_TASK_REQ_DOOR_BELL); > + ufshcd_writel(hba, 1 << task_tag, REG_UTP_TASK_REQ_DOOR_BELL); > /* Make sure that doorbell is committed immediately */ > wmb(); > > @@ -6447,32 +6451,33 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba, > err = wait_for_completion_io_timeout(&wait, > msecs_to_jiffies(TM_CMD_TIMEOUT)); > if (!err) { > + spin_lock_irqsave(hba->host->host_lock, flags); > /* > * Make sure that ufshcd_compl_tm() does not trigger a > * use-after-free. > */ > req->end_io_data = NULL; > + spin_unlock_irqrestore(hba->host->host_lock, flags); > ufshcd_add_tm_upiu_trace(hba, task_tag, "tm_complete_err"); > dev_err(hba->dev, "%s: task management cmd 0x%.2x timed-out\n", > __func__, tm_function); > - if (ufshcd_clear_tm_cmd(hba, free_slot)) > - dev_WARN(hba->dev, "%s: unable clear tm cmd (slot %d) after timeout\n", > - __func__, free_slot); > + if (ufshcd_clear_tm_cmd(hba, task_tag)) { > + dev_WARN(hba->dev, "%s: unable to clear tm cmd (slot %d) after timeout\n", > + __func__, task_tag); > + } else { > + __clear_bit(task_tag, &hba->outstanding_tasks); > + } > err = -ETIMEDOUT; > } else { > err = 0; > - memcpy(treq, hba->utmrdl_base_addr + free_slot, sizeof(*treq)); > + memcpy(treq, hba->utmrdl_base_addr + task_tag, sizeof(*treq)); > > ufshcd_add_tm_upiu_trace(hba, task_tag, "tm_complete"); > } > > - spin_lock_irqsave(hba->host->host_lock, flags); > - __clear_bit(free_slot, &hba->outstanding_tasks); > - spin_unlock_irqrestore(hba->host->host_lock, flags); > - > + ufshcd_release(hba); > blk_put_request(req); > > - ufshcd_release(hba); > return err; > } > > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index fb07e3a..44d09509 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -6252,7 +6252,7 @@ static irqreturn_t ufshcd_check_errors(struct ufs_hba *hba) struct ctm_info { struct ufs_hba *hba; - unsigned long pending; + unsigned long completed; unsigned int ncpl; }; @@ -6261,13 +6261,13 @@ static bool ufshcd_compl_tm(struct request *req, void *priv, bool reserved) struct ctm_info *const ci = priv; struct completion *c; - WARN_ON_ONCE(reserved); - if (test_bit(req->tag, &ci->pending)) - return true; - ci->ncpl++; - c = req->end_io_data; - if (c) - complete(c); + if (test_bit(req->tag, &ci->completed)) { + __clear_bit(req->tag, &hba->outstanding_tasks); + ci->ncpl++; + c = req->end_io_data; + if (c) + complete(c); + } return true; } @@ -6283,11 +6283,19 @@ static irqreturn_t ufshcd_tmc_handler(struct ufs_hba *hba) { struct request_queue *q = hba->tmf_queue; struct ctm_info ci = { - .hba = hba, - .pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL), + .hba = hba, + .ncpl = 0, }; + u32 tm_doorbell; + unsigned long completed; + + tm_doorbell = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL); + completed = tm_doorbell ^ hba->outstanding_tasks; - blk_mq_tagset_busy_iter(q->tag_set, ufshcd_compl_tm, &ci); + if (completed) { + ci.completed = completed; + blk_mq_tagset_busy_iter(q->tag_set, ufshcd_compl_tm, &ci); + } return ci.ncpl ? IRQ_HANDLED : IRQ_NONE; } @@ -6405,37 +6413,33 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba, DECLARE_COMPLETION_ONSTACK(wait); struct request *req; unsigned long flags; - int free_slot, task_tag, err; + int task_tag, err; /* - * Get free slot, sleep if slots are unavailable. - * Even though we use wait_event() which sleeps indefinitely, - * the maximum wait time is bounded by %TM_CMD_TIMEOUT. + * blk_get_request() used here is only to get a free tag. */ req = blk_get_request(q, REQ_OP_DRV_OUT, 0); 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); ufshcd_hold(hba, false); - spin_lock_irqsave(host->host_lock, flags); - task_tag = hba->nutrs + free_slot; + req->end_io_data = &wait; + blk_mq_start_request(req); + task_tag = req->tag; treq->req_header.dword_0 |= cpu_to_be32(task_tag); - memcpy(hba->utmrdl_base_addr + free_slot, treq, sizeof(*treq)); - ufshcd_vops_setup_task_mgmt(hba, free_slot, tm_function); + memcpy(hba->utmrdl_base_addr + task_tag, treq, sizeof(*treq)); + ufshcd_vops_setup_task_mgmt(hba, task_tag, tm_function); /* send command to the controller */ - __set_bit(free_slot, &hba->outstanding_tasks); + __set_bit(task_tag, &hba->outstanding_tasks); /* Make sure descriptors are ready before ringing the task doorbell */ wmb(); - ufshcd_writel(hba, 1 << free_slot, REG_UTP_TASK_REQ_DOOR_BELL); + ufshcd_writel(hba, 1 << task_tag, REG_UTP_TASK_REQ_DOOR_BELL); /* Make sure that doorbell is committed immediately */ wmb(); @@ -6447,32 +6451,33 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba, err = wait_for_completion_io_timeout(&wait, msecs_to_jiffies(TM_CMD_TIMEOUT)); if (!err) { + spin_lock_irqsave(hba->host->host_lock, flags); /* * Make sure that ufshcd_compl_tm() does not trigger a * use-after-free. */ req->end_io_data = NULL; + spin_unlock_irqrestore(hba->host->host_lock, flags); ufshcd_add_tm_upiu_trace(hba, task_tag, "tm_complete_err"); dev_err(hba->dev, "%s: task management cmd 0x%.2x timed-out\n", __func__, tm_function); - if (ufshcd_clear_tm_cmd(hba, free_slot)) - dev_WARN(hba->dev, "%s: unable clear tm cmd (slot %d) after timeout\n", - __func__, free_slot); + if (ufshcd_clear_tm_cmd(hba, task_tag)) { + dev_WARN(hba->dev, "%s: unable to clear tm cmd (slot %d) after timeout\n", + __func__, task_tag); + } else { + __clear_bit(task_tag, &hba->outstanding_tasks); + } err = -ETIMEDOUT; } else { err = 0; - memcpy(treq, hba->utmrdl_base_addr + free_slot, sizeof(*treq)); + memcpy(treq, hba->utmrdl_base_addr + task_tag, sizeof(*treq)); ufshcd_add_tm_upiu_trace(hba, task_tag, "tm_complete"); } - spin_lock_irqsave(hba->host->host_lock, flags); - __clear_bit(free_slot, &hba->outstanding_tasks); - spin_unlock_irqrestore(hba->host->host_lock, flags); - + ufshcd_release(hba); blk_put_request(req); - ufshcd_release(hba); return err; }
Current task management request send/compl implementation is broken, the problems and fixes are listed as below: Problem: TMR completion timeout. ufshcd_tmc_handler() calls blk_mq_tagset_busy_iter(fn == ufshcd_compl_tm()), but since blk_mq_tagset_busy_iter() only iterates over all reserved tags and started requests, so ufshcd_compl_tm() never gets a chance to run. Fix: Call blk_mq_start_request() in __ufshcd_issue_tm_cmd(). Problem: Race condition in send/compl paths. ufshcd_compl_tm() looks for all 0 bits in the REG_UTP_TASK_REQ_DOOR_BELL and call complete() for each req who has the req->end_io_data set. There can be a race condition btw tmc send/compl, because req->end_io_data is set, in __ufshcd_issue_tm_cmd(), without host lock protection, so it is possible that when ufshcd_compl_tm() checks the req->end_io_data, req->end_io_data is set but the corresponding tag has not been set in the REG_UTP_TASK_REQ_DOOR_BELL. Thus, ufshcd_tmc_handler() may wrongly complete TMRs which have not been sent. Fix: Protect req->end_io_data with host lock. And let ufshcd_compl_tm() only handle those tm cmds which have been completed instead of looking for 0 bits in the REG_UTP_TASK_REQ_DOOR_BELL. Problem: In __ufshcd_issue_tm_cmd(), it is not right to use hba->nutrs + req->tag as the Task Tag in one TMR UPIU. Fix: Directly use req->tag as Task Tag. Cc: Jaegeuk Kim <jaegeuk@kernel.org> Signed-off-by: Can Guo <cang@codeaurora.org> --- This change is based on Jaegeuk's change - https://git.kernel.org/mkp/scsi/c/eeb1b55b6e25 ---