scsi: ufs: qcom: Remove the MSI descriptor abuse

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@linutronix.de>
Reviewed-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Link: https://lore.kernel.org/all/20250319105506.805529593@linutronix.de

Author: KAGA-KOKO

drivers/ufs/host/ufs-qcom.c

@@ -1806,25 +1806,38 @@ static void ufs_qcom_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg)
 	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)
@@ -1835,48 +1848,46 @@ static int ufs_qcom_config_esi(struct ufs_hba *hba)
 	 * 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) {
 		dev_err(hba->dev, "Failed to request Platform MSI %d\n", ret);
 		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_and_null_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;
 }
 
 static u32 ufs_qcom_freq_to_gear_speed(struct ufs_hba *hba, unsigned long freq)