linux-kernel - [PATCH] cxl/pmu: Ensure put

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Message-Id: <20231016-pmu-unregister-fix-v1-1-1e2eb2fa3c69@intel.com>
Date:   Mon, 16 Oct 2023 16:25:05 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Davidlohr Bueso <dave@...olabs.net>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Ira Weiny <ira.weiny@...el.com>
Subject: [PATCH] cxl/pmu: Ensure put_device on pmu devices

The following kmemleaks were detected when removing the cxl module
stack:

unreferenced object 0xffff88822616b800 (size 1024):
...
  backtrace:
    [<00000000bedc6f83>] kmalloc_trace+0x26/0x90
    [<00000000448d1afc>] devm_cxl_pmu_add+0x3a/0x110 [cxl_core]
    [<00000000ca3bfe16>] 0xffffffffa105213b
    [<00000000ba7f78dc>] local_pci_probe+0x41/0x90
    [<000000005bb027ac>] pci_device_probe+0xb0/0x1c0
...
unreferenced object 0xffff8882260abcc0 (size 16):
...
  hex dump (first 16 bytes):
    70 6d 75 5f 6d 65 6d 30 2e 30 00 26 82 88 ff ff  pmu_mem0.0.&....
  backtrace:
...
    [<00000000152b5e98>] dev_set_name+0x43/0x50
    [<00000000c228798b>] devm_cxl_pmu_add+0x102/0x110 [cxl_core]
    [<00000000ca3bfe16>] 0xffffffffa105213b
    [<00000000ba7f78dc>] local_pci_probe+0x41/0x90
    [<000000005bb027ac>] pci_device_probe+0xb0/0x1c0
...
unreferenced object 0xffff8882272af200 (size 256):
...
  backtrace:
    [<00000000bedc6f83>] kmalloc_trace+0x26/0x90
    [<00000000a14d1813>] device_add+0x4ea/0x890
    [<00000000a3f07b47>] devm_cxl_pmu_add+0xbe/0x110 [cxl_core]
    [<00000000ca3bfe16>] 0xffffffffa105213b
    [<00000000ba7f78dc>] local_pci_probe+0x41/0x90
    [<000000005bb027ac>] pci_device_probe+0xb0/0x1c0
...

devm_cxl_pmu_add() correctly registers a device remove function but it
only calls device_del() which is only part of device unregistration.

Properly call device_unregister() to free up the memory associated with
the device.

Fixes: 1ad3f701c399 ("cxl/pci: Find and register CXL PMU devices")
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>
Signed-off-by: Ira Weiny <ira.weiny@...el.com>
---
 drivers/cxl/core/pmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cxl/core/pmu.c b/drivers/cxl/core/pmu.c
index 7684c843e5a5..5d8e06b0ba6e 100644
--- a/drivers/cxl/core/pmu.c
+++ b/drivers/cxl/core/pmu.c
@@ -23,7 +23,7 @@ const struct device_type cxl_pmu_type = {
 
 static void remove_dev(void *dev)
 {
-	device_del(dev);
+	device_unregister(dev);
 }
 
 int devm_cxl_pmu_add(struct device *parent, struct cxl_pmu_regs *regs,

---
base-commit: 58720809f52779dc0f08e53e54b014209d13eebb
change-id: 20231016-pmu-unregister-fix-345480926a58

Best regards,
-- 
Ira Weiny <ira.weiny@...el.com>