linux-kernel - [RFC PATCH 6/8] vfio/pci: Move to single error path

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Date:   Wed, 15 Mar 2023 13:59:26 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     jgg@...dia.com, yishaih@...dia.com,
        shameerali.kolothum.thodi@...wei.com, kevin.tian@...el.com,
        alex.williamson@...hat.com
Cc:     tglx@...utronix.de, darwi@...utronix.de, kvm@...r.kernel.org,
        dave.jiang@...el.com, jing2.liu@...el.com, ashok.raj@...el.com,
        fenghua.yu@...el.com, tom.zanussi@...ux.intel.com,
        reinette.chatre@...el.com, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 6/8] vfio/pci: Move to single error path

The creation and release of interrupt context involves several
steps that can fail. Cleanup after failure is done when the error
is encountered, resulting in some repetitive code.

Support for dynamic MSI-X will introduce more steps during
interrupt context creation and release.

Transition to centralized exit path in preparation for dynamic
MSI-X to eliminate duplicate error handling code. Ensure
no remaining state refers to freed memory.

Signed-off-by: Reinette Chatre <reinette.chatre@...el.com>
---
 drivers/vfio/pci/vfio_pci_intrs.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 187a1ba34a16..b375a12885ba 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -460,8 +460,8 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev,
 
 	trigger = eventfd_ctx_fdget(fd);
 	if (IS_ERR(trigger)) {
-		kfree(ctx->name);
-		return PTR_ERR(trigger);
+		ret = PTR_ERR(trigger);
+		goto out_free_name;
 	}
 
 	/*
@@ -481,11 +481,8 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev,
 
 	ret = request_irq(irq, vfio_msihandler, 0, ctx->name, trigger);
 	vfio_pci_memory_unlock_and_restore(vdev, cmd);
-	if (ret) {
-		kfree(ctx->name);
-		eventfd_ctx_put(trigger);
-		return ret;
-	}
+	if (ret)
+		goto out_put_eventfd_ctx;
 
 	ctx->producer.token = trigger;
 	ctx->producer.irq = irq;
@@ -500,6 +497,13 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_core_device *vdev,
 	ctx->trigger = trigger;
 
 	return 0;
+
+out_put_eventfd_ctx:
+	eventfd_ctx_put(trigger);
+out_free_name:
+	kfree(ctx->name);
+	ctx->name = NULL;
+	return ret;
 }
 
 static int vfio_msi_set_block(struct vfio_pci_core_device *vdev, unsigned start,
-- 
2.34.1