linux-kernel - [PATCH v2 1/2] scsi: ufs: core: complete polled requests also from interrupt context

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Message-Id: <20250725-ufshcd-hardirq-v2-1-884c11e0b0df@linaro.org>
Date: Fri, 25 Jul 2025 15:16:15 +0100
From: André Draszik <andre.draszik@...aro.org>
To: Alim Akhtar <alim.akhtar@...sung.com>, 
 Avri Altman <avri.altman@....com>, Bart Van Assche <bvanassche@....org>, 
 "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>, 
 "Martin K. Petersen" <martin.petersen@...cle.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>
Cc: Peter Griffin <peter.griffin@...aro.org>, 
 Tudor Ambarus <tudor.ambarus@...aro.org>, 
 Will McVicker <willmcvicker@...gle.com>, 
 Manivannan Sadhasivam <mani@...nel.org>, kernel-team@...roid.com, 
 linux-arm-msm@...r.kernel.org, linux-samsung-soc@...r.kernel.org, 
 linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 André Draszik <andre.draszik@...aro.org>
Subject: [PATCH v2 1/2] scsi: ufs: core: complete polled requests also from
 interrupt context

When commit ee8c88cab4af ("scsi: ufs: core: Fix the polling
implementation") was added, the block layer did not support completing
polled requests from interrupt context.

This has changed since (presumably with commit b99182c501c3 ("bio: add
pcpu caching for non-polling bio_put")) and it is possible to complete
polled requests also from interrupt context.

Therefore, this commit here changes the code to also complete polled
requests from interrupt context, mostly reverting above referenced
commit as it is not necessary anymore. We do keep the fix to make
ufshcd_poll() return a positive number.

The change has been verified using:
    fio --name=randread --rw=randread --ioengine=pvsync2 --hipri=1 \
        --direct=1 --bs=4k --numjobs=8 --size=32m --runtime=30 \
        --time_based --end_fsync=1 --group_reporting --filename=/foo

which appears to have completed with no errors with this commit.

Suggested-by: Bart Van Assche <bvanassche@....org>
Signed-off-by: André Draszik <andre.draszik@...aro.org>
---
 drivers/ufs/core/ufshcd.c | 26 +-------------------------
 1 file changed, 1 insertion(+), 25 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 13f7e0469141619cfc5e180aa730171ff01b8fb1..d8e2eabacd3efbf07458e81cc4d15ba7f05d3913 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -5613,26 +5613,6 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba,
 		ufshcd_compl_one_cqe(hba, tag, NULL);
 }

-/* Any value that is not an existing queue number is fine for this constant. */
-enum {
-	UFSHCD_POLL_FROM_INTERRUPT_CONTEXT = -1
-};
-
-static void ufshcd_clear_polled(struct ufs_hba *hba,
-				unsigned long *completed_reqs)
-{
-	int tag;
-
-	for_each_set_bit(tag, completed_reqs, hba->nutrs) {
-		struct scsi_cmnd *cmd = hba->lrb[tag].cmd;
-
-		if (!cmd)
-			continue;
-		if (scsi_cmd_to_rq(cmd)->cmd_flags & REQ_POLLED)
-			__clear_bit(tag, completed_reqs);
-	}
-}
-
 /*
  * Return: > 0 if one or more commands have been completed or 0 if no
  * requests have been completed.
@@ -5656,10 +5636,6 @@ static int ufshcd_poll(struct Scsi_Host *shost, unsigned int queue_num)
 	WARN_ONCE(completed_reqs & ~hba->outstanding_reqs,
 		  "completed: %#lx; outstanding: %#lx\n", completed_reqs,
 		  hba->outstanding_reqs);
-	if (queue_num == UFSHCD_POLL_FROM_INTERRUPT_CONTEXT) {
-		/* Do not complete polled requests from interrupt context. */
-		ufshcd_clear_polled(hba, &completed_reqs);
-	}
 	hba->outstanding_reqs &= ~completed_reqs;
 	spin_unlock_irqrestore(&hba->outstanding_lock, flags);

@@ -5747,7 +5723,7 @@ static irqreturn_t ufshcd_transfer_req_compl(struct ufs_hba *hba)
 	 * Ignore the ufshcd_poll() return value and return IRQ_HANDLED since we
 	 * do not want polling to trigger spurious interrupt complaints.
 	 */
-	ufshcd_poll(hba->host, UFSHCD_POLL_FROM_INTERRUPT_CONTEXT);
+	ufshcd_poll(hba->host, 0);

 	return IRQ_HANDLED;
 }

-- 
2.50.1.487.gc89ff58d15-goog