[patch V4 13/14] scsi: ufs: qcom: Remove the MSI descriptor abuse

[Thomas Gleixner]

The driver abuses the MSI descriptors for internal purposes. Aside of core
code and MSI providers nothing has to care about their existence. They have
been encapsulated with a lot of effort because this kind of abuse caused
all sorts of issues including a maintainability nightmare.

Rewrite the code so it uses dedicated storage to hand the required
information to the interrupt handler and use a custom cleanup function to
simplify the error path.

No functional change intended.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Cc: "James E.J. Bottomley" <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: linux-scsi@xxxxxxxxxxxxxxx
---
V4: Fix inverse NULL pointer check and use __free() for error paths - James
---
 drivers/ufs/host/ufs-qcom.c |   85 ++++++++++++++++++++++++--------------------
 1 file changed, 48 insertions(+), 37 deletions(-)

--- a/drivers/ufs/host/ufs-qcom.c
+++ b/drivers/ufs/host/ufs-qcom.c
@@ -1782,25 +1782,38 @@ static void ufs_qcom_write_msi_msg(struc
 	ufshcd_mcq_config_esi(hba, msg);
 }
 
+struct ufs_qcom_irq {
+	unsigned int		irq;
+	unsigned int		idx;
+	struct ufs_hba		*hba;
+};
+
 static irqreturn_t ufs_qcom_mcq_esi_handler(int irq, void *data)
 {
-	struct msi_desc *desc = data;
-	struct device *dev = msi_desc_to_dev(desc);
-	struct ufs_hba *hba = dev_get_drvdata(dev);
-	u32 id = desc->msi_index;
-	struct ufs_hw_queue *hwq = &hba->uhq[id];
+	struct ufs_qcom_irq *qi = data;
+	struct ufs_hba *hba = qi->hba;
+	struct ufs_hw_queue *hwq = &hba->uhq[qi->idx];
 
-	ufshcd_mcq_write_cqis(hba, 0x1, id);
+	ufshcd_mcq_write_cqis(hba, 0x1, qi->idx);
 	ufshcd_mcq_poll_cqe_lock(hba, hwq);
 
 	return IRQ_HANDLED;
 }
 
+static void ufs_qcom_irq_free(struct ufs_qcom_irq *uqi)
+{
+	for (struct ufs_qcom_irq *q = uqi; q->irq; q++)
+		devm_free_irq(q->hba->dev, q->irq, q->hba);
+
+	platform_device_msi_free_irqs_all(uqi->hba->dev);
+	devm_kfree(uqi->hba->dev, uqi);
+}
+
+DEFINE_FREE(ufs_qcom_irq, struct ufs_qcom_irq *, if (_T) ufs_qcom_irq_free(_T))
+
 static int ufs_qcom_config_esi(struct ufs_hba *hba)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
-	struct msi_desc *desc;
-	struct msi_desc *failed_desc = NULL;
 	int nr_irqs, ret;
 
 	if (host->esi_enabled)
@@ -1811,6 +1824,14 @@ static int ufs_qcom_config_esi(struct uf
 	 * 2. Poll queues do not need ESI.
 	 */
 	nr_irqs = hba->nr_hw_queues - hba->nr_queues[HCTX_TYPE_POLL];
+
+	struct ufs_qcom_irq *qi __free(ufs_qcom_irq) =
+		devm_kcalloc(hba->dev, nr_irqs, sizeof(*qi), GFP_KERNEL);
+	if (!qi)
+		return -ENOMEM;
+	/* Preset so __free() has a pointer to hba in all error paths */
+	qi[0].hba = hba;
+
 	ret = platform_device_msi_init_and_alloc_irqs(hba->dev, nr_irqs,
 						      ufs_qcom_write_msi_msg);
 	if (ret) {
@@ -1818,41 +1839,31 @@ static int ufs_qcom_config_esi(struct uf
 		return ret;
 	}
 
-	msi_lock_descs(hba->dev);
-	msi_for_each_desc(desc, hba->dev, MSI_DESC_ALL) {
-		ret = devm_request_irq(hba->dev, desc->irq,
-				       ufs_qcom_mcq_esi_handler,
-				       IRQF_SHARED, "qcom-mcq-esi", desc);
+	for (int idx = 0; idx < nr_irqs; idx++) {
+		qi[idx].irq = msi_get_virq(hba->dev, idx);
+		qi[idx].idx = idx;
+		qi[idx].hba = hba;
+
+		ret = devm_request_irq(hba->dev, qi[idx].irq, ufs_qcom_mcq_esi_handler,
+				       IRQF_SHARED, "qcom-mcq-esi", qi + idx);
 		if (ret) {
 			dev_err(hba->dev, "%s: Fail to request IRQ for %d, err = %d\n",
-				__func__, desc->irq, ret);
-			failed_desc = desc;
-			break;
+				__func__, qi[idx].irq, ret);
+			qi[idx].irq = 0;
+			return ret;
 		}
 	}
-	msi_unlock_descs(hba->dev);
 
-	if (ret) {
-		/* Rewind */
-		msi_lock_descs(hba->dev);
-		msi_for_each_desc(desc, hba->dev, MSI_DESC_ALL) {
-			if (desc == failed_desc)
-				break;
-			devm_free_irq(hba->dev, desc->irq, hba);
-		}
-		msi_unlock_descs(hba->dev);
-		platform_device_msi_free_irqs_all(hba->dev);
-	} else {
-		if (host->hw_ver.major == 6 && host->hw_ver.minor == 0 &&
-		    host->hw_ver.step == 0)
-			ufshcd_rmwl(hba, ESI_VEC_MASK,
-				    FIELD_PREP(ESI_VEC_MASK, MAX_ESI_VEC - 1),
-				    REG_UFS_CFG3);
-		ufshcd_mcq_enable_esi(hba);
-		host->esi_enabled = true;
-	}
+	retain_ptr(qi);
 
-	return ret;
+	if (host->hw_ver.major == 6 && host->hw_ver.minor == 0 &&
+	    host->hw_ver.step == 0) {
+		ufshcd_rmwl(hba, ESI_VEC_MASK, FIELD_PREP(ESI_VEC_MASK, MAX_ESI_VEC - 1),
+			    REG_UFS_CFG3);
+	}
+	ufshcd_mcq_enable_esi(hba);
+	host->esi_enabled = true;
+	return 0;
 }
 
 /*