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 <jaeg...@kernel.org> Signed-off-by: Can Guo <c...@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); + 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.