linux-kernel - [PATCH 8/9] dmaengine: idxd: Fix freeing the allocated ida too late

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Message-Id: <20250804-idxd-fix-flr-on-kernel-queues-v3-v1-8-4e020fbf52c1@intel.com>
Date: Mon, 04 Aug 2025 18:27:59 -0700
From: Vinicius Costa Gomes <vinicius.gomes@...el.com>
To: Dave Jiang <dave.jiang@...el.com>, Vinod Koul <vkoul@...nel.org>, 
 Fenghua Yu <fenghua.yu@...el.com>, Dan Williams <dan.j.williams@...el.com>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Vinicius Costa Gomes <vinicius.gomes@...el.com>
Subject: [PATCH 8/9] dmaengine: idxd: Fix freeing the allocated ida too
 late

It can happen that when the cdev .release() is called, the driver
already called ida_destroy(). Move ida_free() to the _del() path.

We see with DEBUG_KOBJECT_RELEASE enabled and forcing an early PCI
unbind.

Fixes: 04922b7445a1 ("dmaengine: idxd: fix cdev setup and free device lifetime issues")
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
---
 drivers/dma/idxd/cdev.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index 7e4715f927732702416d917f34ab0a83f575d533..4105688cf3f060704b851ee17467c135c170326e 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -158,11 +158,7 @@ static const struct device_type idxd_cdev_file_type = {
 static void idxd_cdev_dev_release(struct device *dev)
 {
 	struct idxd_cdev *idxd_cdev = dev_to_cdev(dev);
-	struct idxd_cdev_context *cdev_ctx;
-	struct idxd_wq *wq = idxd_cdev->wq;
 
-	cdev_ctx = &ictx[wq->idxd->data->type];
-	ida_free(&cdev_ctx->minor_ida, idxd_cdev->minor);
 	kfree(idxd_cdev);
 }
 
@@ -582,11 +578,15 @@ int idxd_wq_add_cdev(struct idxd_wq *wq)
 
 void idxd_wq_del_cdev(struct idxd_wq *wq)
 {
+	struct idxd_cdev_context *cdev_ctx;
 	struct idxd_cdev *idxd_cdev;
 
 	idxd_cdev = wq->idxd_cdev;
 	wq->idxd_cdev = NULL;
 	cdev_device_del(&idxd_cdev->cdev, cdev_dev(idxd_cdev));
+
+	cdev_ctx = &ictx[wq->idxd->data->type];
+	ida_free(&cdev_ctx->minor_ida, idxd_cdev->minor);
 	put_device(cdev_dev(idxd_cdev));
 }
 

-- 
2.50.1