2022-08-29 19:46:59

by Korneliusz Osmenda

Subject: [PATCH] Guard pci_create_sysfs_dev_files with atomic value

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 <[email protected]>
---
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

2022-10-06 10:10:41

by Alexander Stein

Subject: Re: [PATCH] Guard pci_create_sysfs_dev_files with atomic value

Hi,

Am Montag, 29. August 2022, 21:14:43 CEST schrieb Korneliusz Osmenda:
> 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 <[email protected]>
> ---
> 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? */

Is there any feedback here? I'm hitting the same issue on TQMa6x+MBa6x.
Having this patch applied my PCIe device using several bridges is detected
fine.

root@tqma6-common:~# lspci
00:00.0 PCI bridge: Synopsys, Inc. DWC_usb3 / PCIe bridge (rev 01)
01:00.0 PCI bridge: Pericom Semiconductor Device a303 (rev 03)
02:01.0 PCI bridge: Pericom Semiconductor Device a303 (rev 03)
02:02.0 PCI bridge: Pericom Semiconductor Device a303 (rev 03)
03:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411
PCI Express Gigabit Ethernet Controller (rev 0c)
04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411
PCI Express Gigabit Ethernet Controller (rev 0c)

root@tqma6-common:~# lspci -t
-[0000:00]---00.0-[01-ff]----00.0-[02-04]--+-01.0-[03]----00.0
\-02.0-[04]----00.0

Best regards,
Alexander