RE: [PATCH 5.10 83/83] scsi: ufs: core: Fix task management completion

Hunter, Adrian
2021-10-11T15:15:39Z

Hi

This doesn't work. Please drop. Sorry, no idea why I sent it before testing.

Specifically, in v5.10, ufshcd_tmc_handler() can be called under the same spinlock
it is using, which deadlocks.

Regards
Adrian

> -----Original Message-----
> From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Sent: Monday, October 11, 2021 4:47 PM
> To: linux-kernel@vger.kernel.org
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>;
> stable@vger.kernel.org; Bart Van Assche <bvanassche@acm.org>; Hunter,
> Adrian <adrian.hunter@intel.com>; Martin K. Petersen
> <martin.petersen@oracle.com>
> Subject: [PATCH 5.10 83/83] scsi: ufs: core: Fix task management completion
>
> From: Adrian Hunter <adrian.hunter@intel.com>
>
> commit f5ef336fd2e4c36dedae4e7ca66cf5349d6fda62 upstream.
>
> 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 37f4a24c2469
> ("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.
>
> Link: https://lore.kernel.org/r/20210922091059.4040-1-
> adrian.hunter@intel.com
> Fixes: 1235fc569e0b ("scsi: ufs: core: Fix task management request
> completion timeout")
> Fixes: 69a6c269c097 ("scsi: ufs: Use blk_{get,put}_request() to allocate and
> free TMFs")
> Cc: stable@vger.kernel.org
> Tested-by: Bart Van Assche <bvanassche@acm.org>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> ---
> drivers/scsi/ufs/ufshcd.c | 54 +++++++++++++++++++++----------------------
> ---
> drivers/scsi/ufs/ufshcd.h | 1
> 2 files changed, 26 insertions(+), 29 deletions(-)
>
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -6105,27 +6105,6 @@ static irqreturn_t ufshcd_check_errors(s
> 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
> @@ -6136,14 +6115,24 @@ static bool ufshcd_compl_tm(struct reque
> */
> 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),
> - };
> + unsigned long flags, pending, issued;
> + irqreturn_t ret = IRQ_NONE;
> + int tag;
>
> - blk_mq_tagset_busy_iter(q->tag_set, ufshcd_compl_tm, &ci);
> - return ci.ncpl ? IRQ_HANDLED : IRQ_NONE;
> + pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL);
> +
> + spin_lock_irqsave(hba->host->host_lock, flags);
> + 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 ret;
> }
>
> /**
> @@ -6273,9 +6262,9 @@ static int __ufshcd_issue_tm_cmd(struct
> 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->req_header.dword_0 |= cpu_to_be32(task_tag);
>
> memcpy(hba->utmrdl_base_addr + task_tag, treq, sizeof(*treq));
> @@ -6319,6 +6308,7 @@ static int __ufshcd_issue_tm_cmd(struct
> }
>
> 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);
>
> @@ -9246,6 +9236,12 @@ int ufshcd_init(struct ufs_hba *hba, voi
> 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_vops_device_reset(hba);
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -731,6 +731,7 @@ 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;
>