Patch "PCI/DOE: Silence WARN splat with CONFIG_DEBUG_OBJECTS=y" has been added to the 6.2-stable tree

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This is a note to let you know that I've just added the patch titled

    PCI/DOE: Silence WARN splat with CONFIG_DEBUG_OBJECTS=y

to the 6.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pci-doe-silence-warn-splat-with-config_debug_objects-y.patch
and it can be found in the queue-6.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 92dc899c3b4927f3cfa23f55bf759171234b5802 Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@xxxxxxxxx>
Date: Sat, 11 Mar 2023 15:40:05 +0100
Subject: PCI/DOE: Silence WARN splat with CONFIG_DEBUG_OBJECTS=y

From: Lukas Wunner <lukas@xxxxxxxxx>

commit 92dc899c3b4927f3cfa23f55bf759171234b5802 upstream.

Gregory Price reports a WARN splat with CONFIG_DEBUG_OBJECTS=y upon CXL
probing because pci_doe_submit_task() invokes INIT_WORK() instead of
INIT_WORK_ONSTACK() for a work_struct that was allocated on the stack.

All callers of pci_doe_submit_task() allocate the work_struct on the
stack, so replace INIT_WORK() with INIT_WORK_ONSTACK() as a backportable
short-term fix.

The long-term fix implemented by a subsequent commit is to move to a
synchronous API which allocates the work_struct internally in the DOE
library.

Stacktrace for posterity:

WARNING: CPU: 0 PID: 23 at lib/debugobjects.c:545 __debug_object_init.cold+0x18/0x183
CPU: 0 PID: 23 Comm: kworker/u2:1 Not tainted 6.1.0-0.rc1.20221019gitaae703b02f92.17.fc38.x86_64 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Call Trace:
 pci_doe_submit_task+0x5d/0xd0
 pci_doe_discovery+0xb4/0x100
 pcim_doe_create_mb+0x219/0x290
 cxl_pci_probe+0x192/0x430
 local_pci_probe+0x41/0x80
 pci_device_probe+0xb3/0x220
 really_probe+0xde/0x380
 __driver_probe_device+0x78/0x170
 driver_probe_device+0x1f/0x90
 __driver_attach_async_helper+0x5c/0xe0
 async_run_entry_fn+0x30/0x130
 process_one_work+0x294/0x5b0

Fixes: 9d24322e887b ("PCI/DOE: Add DOE mailbox support functions")
Link: https://lore.kernel.org/linux-cxl/Y1bOniJliOFszvIK@xxxxxxxxxxxx/
Reported-by: Gregory Price <gregory.price@xxxxxxxxxxxx>
Tested-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Tested-by: Gregory Price <gregory.price@xxxxxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx>
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Reviewed-by: Gregory Price <gregory.price@xxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v6.0+
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Link: https://lore.kernel.org/r/67a9117f463ecdb38a2dbca6a20391ce2f1e7a06.1678543498.git.lukas@xxxxxxxxx
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/pci/doe.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/pci/doe.c
+++ b/drivers/pci/doe.c
@@ -523,6 +523,8 @@ EXPORT_SYMBOL_GPL(pci_doe_supports_prot)
  * task->complete will be called when the state machine is done processing this
  * task.
  *
+ * @task must be allocated on the stack.
+ *
  * Excess data will be discarded.
  *
  * RETURNS: 0 when task has been successfully queued, -ERRNO on error
@@ -544,7 +546,7 @@ int pci_doe_submit_task(struct pci_doe_m
 		return -EIO;
 
 	task->doe_mb = doe_mb;
-	INIT_WORK(&task->work, doe_statemachine_work);
+	INIT_WORK_ONSTACK(&task->work, doe_statemachine_work);
 	queue_work(doe_mb->work_queue, &task->work);
 	return 0;
 }


Patches currently in stable-queue which might be from lukas@xxxxxxxxx are

queue-6.2/pci-doe-fix-memory-leak-with-config_debug_objects-y.patch
queue-6.2/cxl-pci-handle-truncated-cdat-entries.patch
queue-6.2/cxl-pci-handle-truncated-cdat-header.patch
queue-6.2/cxl-pci-fix-cdat-retrieval-on-big-endian.patch
queue-6.2/pci-doe-silence-warn-splat-with-config_debug_objects-y.patch
queue-6.2/cxl-pci-handle-excessive-cdat-length.patch



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