[PATCH 5.14 034/151] scsi: ufs: core: Fix task management completion

Greg Kroah-Hartman
2021-10-11T14:02:50Z

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 | 52 +++++++++++++++++++---------------------------
drivers/scsi/ufs/ufshcd.h | 1
2 files changed, 23 insertions(+), 30 deletions(-)

--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6365,27 +6365,6 @@ 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
@@ -6396,18 +6375,24 @@ static bool ufshcd_compl_tm(struct reque
*/
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;
}

/**
@@ -6530,9 +6515,9 @@ 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->upiu_req.req_header.dword_0 |= cpu_to_be32(task_tag);

memcpy(hba->utmrdl_base_addr + task_tag, treq, sizeof(*treq));
@@ -6576,6 +6561,7 @@ 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);

@@ -9568,6 +9554,12 @@ 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_device_reset(hba);
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -780,6 +780,7 @@ 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;