From dc6b698a86fe40a50525433eb8e92a267847f6f9 Mon Sep 17 00:00:00 2001
From: Marek Vasut <marek.vasut+renesas@gmail.com>
Date: Mon, 27 May 2019 00:51:51 +0200
Subject: [PATCH] PCI: sysfs: Ignore lockdep for remove attribute
Git-commit: dc6b698a86fe40a50525433eb8e92a267847f6f9
Patch-mainline: v5.3-rc1
References: git-fixes

With CONFIG_PROVE_LOCKING=y, using sysfs to remove a bridge with a device
below it causes a lockdep warning, e.g.,

  # echo 1 > /sys/class/pci_bus/0000:00/device/0000:00:00.0/remove
  ============================================
  WARNING: possible recursive locking detected
  ...
  pci_bus 0000:01: busn_res: [bus 01] is released

The remove recursively removes the subtree below the bridge.  Each call
uses a different lock so there's no deadlock, but the locks were all
created with the same lockdep key so the lockdep checker can't tell them
apart.

Mark the "remove" sysfs attribute with __ATTR_IGNORE_LOCKDEP() as it is
safe to ignore the lockdep check between different "remove" kernfs
instances.

There's discussion about a similar issue in USB at [1], which resulted in
356c05d58af0 ("sysfs: get rid of some lockdep false positives") and
e9b526fe7048 ("i2c: suppress lockdep warning on delete_device"), which do
basically the same thing for USB "remove" and i2c "delete_device" files.

[1] https://lore.kernel.org/r/Pine.LNX.4.44L0.1204251436140.1206-100000@iolanthe.rowland.org

Link: https://lore.kernel.org/r/20190526225151.3865-1-marek.vasut@gmail.com
Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
[bhelgaas: trim commit log, details at above links]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Phil Edworthy <phil.edworthy@renesas.com>
Cc: Simon Horman <horms+renesas@verge.net.au>
Cc: Tejun Heo <tj@kernel.org>
Cc: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/pci/pci-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index d52d30448e41..965c72104150 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -480,7 +480,7 @@ static ssize_t remove_store(struct device *dev, struct device_attribute *attr,
 		pci_stop_and_remove_bus_device_locked(to_pci_dev(dev));
 	return count;
 }
-static struct device_attribute dev_remove_attr = __ATTR(remove,
+static struct device_attribute dev_remove_attr = __ATTR_IGNORE_LOCKDEP(remove,
 							(S_IWUSR|S_IWGRP),
 							NULL, remove_store);
 
-- 
2.16.4