[PATCH] Guard pci_create_sysfs_dev_files with atomic value

[Korneliusz Osmenda <korneliuszo@gmail.com>]

On Gateworks Ventana there is a number of PCI devices and:
  - imx6_pcie_probe takes longer than start of late init
  - pci_sysfs_init sets up flag sysfs_initialized
  - pci_sysfs_init initializes already found devices
  - imx6_pcie_probe tries to reinitialize device

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=215515

Signed-off-by: Korneliusz Osmenda <korneliuszo@gmail.com>
---
  drivers/pci/pci-sysfs.c | 6 ++++++
  include/linux/pci.h     | 2 ++
  2 files changed, 8 insertions(+)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index fc804e08e3cb..a6648239e235 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1378,6 +1378,9 @@ int __must_check pci_create_sysfs_dev_files(struct 
pci_dev *pdev)
  	if (!sysfs_initialized)
  		return -EACCES;

+	if (atomic_cmpxchg(&pdev->sysfs_init_cnt,0,1) == 1)
+		return 0;		/* already added */
+
  	return pci_create_resource_files(pdev);
  }

@@ -1392,6 +1395,9 @@ void pci_remove_sysfs_dev_files(struct pci_dev *pdev)
  	if (!sysfs_initialized)
  		return;

+	if (atomic_cmpxchg(&pdev->sysfs_init_cnt,1,0) == 0)
+		return;		/* already removed */
+
  	pci_remove_resource_files(pdev);
  }

diff --git a/include/linux/pci.h b/include/linux/pci.h
index 060af91bafcd..5477de2ef057 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -465,6 +465,8 @@ struct pci_dev {
  	pci_dev_flags_t dev_flags;
  	atomic_t	enable_cnt;	/* pci_enable_device has been called */

+	atomic_t	sysfs_init_cnt;	/* pci_create_sysfs_dev_files has been called */
+
  	u32		saved_config_space[16]; /* Config space saved at suspend time */
  	struct hlist_head saved_cap_space;
  	int		rom_attr_enabled;	/* Display of ROM attribute enabled? */
-- 
2.36.1