| Message ID | 20210922091059.4040-1-adrian.hunter@intel.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | scsi: ufs: Fix task management completion | expand |
On 9/22/21 2:10 AM, Adrian Hunter wrote: > The UFS driver uses blk_mq_tagset_busy_iter() when identifying task > management requests to complete, however blk_mq_tagset_busy_iter() > doesn't work. > > blk_mq_tagset_busy_iter() only iterates requests dispatched by the block > layer. That appears as if it might have started since commit 37f4a24c2469a1 > ("blk-mq: centralise related handling into blk_mq_get_driver_tag") which > removed 'data->hctx->tags->rqs[rq->tag] = rq' from blk_mq_rq_ctx_init() > which gets called: > > blk_get_request > blk_mq_alloc_request > __blk_mq_alloc_request > blk_mq_rq_ctx_init > > Since UFS task management requests are not dispatched by the block > layer, hctx->tags->rqs[rq->tag] remains NULL, and since > blk_mq_tagset_busy_iter() relies on finding requests using > hctx->tags->rqs[rq->tag], UFS task management requests are never found by > blk_mq_tagset_busy_iter(). > > By using blk_mq_tagset_busy_iter(), the UFS driver was relying on internal > details of the block layer, which was fragile and subsequently got > broken. Fix by removing the use of blk_mq_tagset_busy_iter() and having > the driver keep track of task management requests. Thanks for the detailed analysis. I agree that using blk_mq_tagset_busy_iter() no longer works due to recent changes in the block layer. Has it been considered to export blk_mq_all_tag_iter() and to use that function instead of blk_mq_tagset_busy_iter()? Thanks, Bart.
On 22/09/21 11:48 pm, Bart Van Assche wrote: > On 9/22/21 2:10 AM, Adrian Hunter wrote: >> The UFS driver uses blk_mq_tagset_busy_iter() when identifying task >> management requests to complete, however blk_mq_tagset_busy_iter() >> doesn't work. >> >> blk_mq_tagset_busy_iter() only iterates requests dispatched by the block >> layer. That appears as if it might have started since commit 37f4a24c2469a1 >> ("blk-mq: centralise related handling into blk_mq_get_driver_tag") which >> removed 'data->hctx->tags->rqs[rq->tag] = rq' from blk_mq_rq_ctx_init() >> which gets called: >> >> blk_get_request >> blk_mq_alloc_request >> __blk_mq_alloc_request >> blk_mq_rq_ctx_init >> >> Since UFS task management requests are not dispatched by the block >> layer, hctx->tags->rqs[rq->tag] remains NULL, and since >> blk_mq_tagset_busy_iter() relies on finding requests using >> hctx->tags->rqs[rq->tag], UFS task management requests are never found by >> blk_mq_tagset_busy_iter(). >> >> By using blk_mq_tagset_busy_iter(), the UFS driver was relying on internal >> details of the block layer, which was fragile and subsequently got >> broken. Fix by removing the use of blk_mq_tagset_busy_iter() and having >> the driver keep track of task management requests. > > Thanks for the detailed analysis. I agree that using blk_mq_tagset_busy_iter() > no longer works due to recent changes in the block layer. Has it been > considered to export blk_mq_all_tag_iter() and to use that function instead of > blk_mq_tagset_busy_iter()? It seemed better not to be the only driver using the block layer in a different way. Having the UFS driver self-contained in this regard seemed more robust. If anything, the code without blk_mq_tagset_busy_iter() is slightly shorter, so using a block layer iterator doesn't help much.
On 9/22/21 2:10 AM, Adrian Hunter wrote: > By using blk_mq_tagset_busy_iter(), the UFS driver was relying on internal > details of the block layer, which was fragile and subsequently got > broken. Fix by removing the use of blk_mq_tagset_busy_iter() and having > the driver keep track of task management requests. Tested-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
On Wed, 22 Sep 2021 12:10:59 +0300, Adrian Hunter wrote: > The UFS driver uses blk_mq_tagset_busy_iter() when identifying task > management requests to complete, however blk_mq_tagset_busy_iter() > doesn't work. > > blk_mq_tagset_busy_iter() only iterates requests dispatched by the block > layer. That appears as if it might have started since commit 37f4a24c2469a1 > ("blk-mq: centralise related handling into blk_mq_get_driver_tag") which > removed 'data->hctx->tags->rqs[rq->tag] = rq' from blk_mq_rq_ctx_init() > which gets called: > > [...] Applied to 5.15/scsi-fixes, thanks! [1/1] scsi: ufs: Fix task management completion https://git.kernel.org/mkp/scsi/c/f5ef336fd2e4
diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index 029c9631ec2b..1f97818aa0bf 100644 --- a/drivers/scsi/ufs/ufshcd.c +++ b/drivers/scsi/ufs/ufshcd.c @@ -6378,27 +6378,6 @@ static irqreturn_t ufshcd_check_errors(struct ufs_hba *hba, u32 intr_status) return retval; } -struct ctm_info { - struct ufs_hba *hba; - unsigned long pending; - unsigned int ncpl; -}; - -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); - return true; -} - /** * ufshcd_tmc_handler - handle task management function completion * @hba: per adapter instance @@ -6409,18 +6388,24 @@ static bool ufshcd_compl_tm(struct request *req, void *priv, bool reserved) */ static irqreturn_t ufshcd_tmc_handler(struct ufs_hba *hba) { - unsigned long flags; - struct request_queue *q = hba->tmf_queue; - struct ctm_info ci = { - .hba = hba, - }; + unsigned long flags, pending, issued; + irqreturn_t ret = IRQ_NONE; + int tag; + + pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL); spin_lock_irqsave(hba->host->host_lock, flags); - ci.pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL); - blk_mq_tagset_busy_iter(q->tag_set, ufshcd_compl_tm, &ci); + issued = hba->outstanding_tasks & ~pending; + for_each_set_bit(tag, &issued, hba->nutmrs) { + struct request *req = hba->tmf_rqs[tag]; + struct completion *c = req->end_io_data; + + complete(c); + ret = IRQ_HANDLED; + } spin_unlock_irqrestore(hba->host->host_lock, flags); - return ci.ncpl ? IRQ_HANDLED : IRQ_NONE; + return ret; } /** @@ -6543,9 +6528,9 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba, ufshcd_hold(hba, false); spin_lock_irqsave(host->host_lock, flags); - blk_mq_start_request(req); task_tag = req->tag; + hba->tmf_rqs[req->tag] = req; treq->upiu_req.req_header.dword_0 |= cpu_to_be32(task_tag); memcpy(hba->utmrdl_base_addr + task_tag, treq, sizeof(*treq)); @@ -6586,6 +6571,7 @@ static int __ufshcd_issue_tm_cmd(struct ufs_hba *hba, } spin_lock_irqsave(hba->host->host_lock, flags); + hba->tmf_rqs[req->tag] = NULL; __clear_bit(task_tag, &hba->outstanding_tasks); spin_unlock_irqrestore(hba->host->host_lock, flags); @@ -9636,6 +9622,12 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq) err = PTR_ERR(hba->tmf_queue); goto free_tmf_tag_set; } + hba->tmf_rqs = devm_kcalloc(hba->dev, hba->nutmrs, + sizeof(*hba->tmf_rqs), GFP_KERNEL); + if (!hba->tmf_rqs) { + err = -ENOMEM; + goto free_tmf_queue; + } /* Reset the attached device */ ufshcd_device_reset(hba); diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h index f0da5d3db1fa..41f6e06f9185 100644 --- a/drivers/scsi/ufs/ufshcd.h +++ b/drivers/scsi/ufs/ufshcd.h @@ -828,6 +828,7 @@ struct ufs_hba { struct blk_mq_tag_set tmf_tag_set; struct request_queue *tmf_queue; + struct request **tmf_rqs; struct uic_command *active_uic_cmd; struct mutex uic_cmd_mutex;
The UFS driver uses blk_mq_tagset_busy_iter() when identifying task management requests to complete, however blk_mq_tagset_busy_iter() doesn't work. blk_mq_tagset_busy_iter() only iterates requests dispatched by the block layer. That appears as if it might have started since commit 37f4a24c2469a1 ("blk-mq: centralise related handling into blk_mq_get_driver_tag") which removed 'data->hctx->tags->rqs[rq->tag] = rq' from blk_mq_rq_ctx_init() which gets called: blk_get_request blk_mq_alloc_request __blk_mq_alloc_request blk_mq_rq_ctx_init Since UFS task management requests are not dispatched by the block layer, hctx->tags->rqs[rq->tag] remains NULL, and since blk_mq_tagset_busy_iter() relies on finding requests using hctx->tags->rqs[rq->tag], UFS task management requests are never found by blk_mq_tagset_busy_iter(). By using blk_mq_tagset_busy_iter(), the UFS driver was relying on internal details of the block layer, which was fragile and subsequently got broken. Fix by removing the use of blk_mq_tagset_busy_iter() and having the driver keep track of task management requests. Fixes: 1235fc569e0bf5 ("scsi: ufs: core: Fix task management request completion timeout") Fixes: 69a6c269c097d7 ("scsi: ufs: Use blk_{get,put}_request() to allocate and free TMFs") Cc: stable@vger.kernel.org Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> --- drivers/scsi/ufs/ufshcd.c | 52 +++++++++++++++++---------------------- drivers/scsi/ufs/ufshcd.h | 1 + 2 files changed, 23 insertions(+), 30 deletions(-)