linux-kernel - [PATCH v2 2/2] dmaengine: idxd: Fix refcount underflow on module unload

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Message-ID: <20250607130616.514984-3-yi.sun@intel.com>
Date: Sat,  7 Jun 2025 21:06:16 +0800
From: Yi Sun <yi.sun@...el.com>
To: vinicius.gomes@...el.com,
	dmaengine@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: yi.sun@...el.com,
	gordon.jin@...el.com
Subject: [PATCH v2 2/2] dmaengine: idxd: Fix refcount underflow on module unload

A recent refactor introduced a misplaced put_device() call, leading to a
reference count underflow during module unload.

There is no need to add additional put_device() calls for idxd groups,
engines, or workqueues. Although commit a409e919ca3 claims:"Note, this
also fixes the missing put_device() for idxd groups, engines, and wqs."
It appears no such omission existed. The required cleanup is already
handled by the call chain:
idxd_unregister_devices() -> device_unregister() -> put_device()

Extend idxd_cleanup() to perform the necessary cleanup, and remove
idxd_cleanup_internals() which was not originally part of the driver
unload path and introduced unintended reference count underflow.

Fixes: a409e919ca32 ("dmaengine: idxd: Refactor remove call with idxd_cleanup() helper")
Signed-off-by: Yi Sun <yi.sun@...el.com>

diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
index 504aca0fd597..a5eabeb6a8bd 100644
--- a/drivers/dma/idxd/init.c
+++ b/drivers/dma/idxd/init.c
@@ -1321,7 +1321,12 @@ static void idxd_remove(struct pci_dev *pdev)
 	device_unregister(idxd_confdev(idxd));
 	idxd_shutdown(pdev);
 	idxd_device_remove_debugfs(idxd);
-	idxd_cleanup(idxd);
+	perfmon_pmu_remove(idxd);
+	idxd_cleanup_interrupts(idxd);
+	if (device_pasid_enabled(idxd))
+		idxd_disable_system_pasid(idxd);
+	if (device_user_pasid_enabled(idxd))
+		idxd_disable_sva(idxd->pdev);
 	pci_iounmap(pdev, idxd->reg_base);
 	put_device(idxd_confdev(idxd));
 	pci_disable_device(pdev);
-- 
2.43.0