Both pci_create_sysfs_dev_files() and pci_proc_attach_device() are called
from pci_bus_add_device(). Calling these APIs from other places is prone to
a race condition as nothing prevents the callers from racing against
each other.

Moreover, the proper place to create SYSFS and PROCFS entries is during
the 'pci_dev' creation. So there is no real need to call these APIs
elsewhere.

Hence, remove the calls from pci_sysfs_init() and pci_proc_init().

Reported-by: Shuan He <heshuan@bytedance.com>
Closes: https://lore.kernel.org/linux-pci/20250702155112.40124-1-heshuan@bytedance.com
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/pci/pci-sysfs.c | 9 ---------
 drivers/pci/proc.c      | 3 ---
 2 files changed, 12 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 268c69daa4d5..8e712c14e6ea 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1676,18 +1676,9 @@ void pci_remove_sysfs_dev_files(struct pci_dev *pdev)
 
 static int __init pci_sysfs_init(void)
 {
-	struct pci_dev *pdev = NULL;
 	struct pci_bus *pbus = NULL;
-	int retval;
 
 	sysfs_initialized = 1;
-	for_each_pci_dev(pdev) {
-		retval = pci_create_sysfs_dev_files(pdev);
-		if (retval) {
-			pci_dev_put(pdev);
-			return retval;
-		}
-	}
 
 	while ((pbus = pci_find_next_bus(pbus)))
 		pci_create_legacy_files(pbus);
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index 9348a0fb8084..b78286afe18e 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -463,13 +463,10 @@ int pci_proc_detach_bus(struct pci_bus *bus)
 
 static int __init pci_proc_init(void)
 {
-	struct pci_dev *dev = NULL;
 	proc_bus_pci_dir = proc_mkdir("bus/pci", NULL);
 	proc_create_seq("devices", 0, proc_bus_pci_dir,
 		    &proc_bus_pci_devices_op);
 	proc_initialized = 1;
-	for_each_pci_dev(dev)
-		pci_proc_attach_device(dev);
 
 	return 0;
 }
-- 
2.45.2

On Wed, Jul 23, 2025 at 04:41:24PM +0530, Manivannan Sadhasivam wrote:
> Both pci_create_sysfs_dev_files() and pci_proc_attach_device() are called
> from pci_bus_add_device(). Calling these APIs from other places is prone to
> a race condition as nothing prevents the callers from racing against
> each other.
> 
> Moreover, the proper place to create SYSFS and PROCFS entries is during
> the 'pci_dev' creation. So there is no real need to call these APIs
> elsewhere.

The raison d'être for the call to pci_create_sysfs_dev_files() in
pci_sysfs_init() is that PCI_ROM_RESOURCEs may appear after device
enumeration but before the late_initcall stage:

https://lore.kernel.org/r/20231019200110.GA1410324@bhelgaas/

Your patch will regress those platforms.

The proper solution is to make the resource files in sysfs static
and call sysfs_update_group() from pci_sysfs_init().

Krzysztof has an old branch where he started working on this:

https://github.com/kwilczynski/linux/commits/kwilczynski/sysfs-static-resource-attributes/

Thanks,

Lukas

On Wed, Jul 23, 2025 at 02:55:28PM GMT, Lukas Wunner wrote:
> On Wed, Jul 23, 2025 at 04:41:24PM +0530, Manivannan Sadhasivam wrote:
> > Both pci_create_sysfs_dev_files() and pci_proc_attach_device() are called
> > from pci_bus_add_device(). Calling these APIs from other places is prone to
> > a race condition as nothing prevents the callers from racing against
> > each other.
> > 
> > Moreover, the proper place to create SYSFS and PROCFS entries is during
> > the 'pci_dev' creation. So there is no real need to call these APIs
> > elsewhere.
> 
> The raison d'être for the call to pci_create_sysfs_dev_files() in
> pci_sysfs_init() is that PCI_ROM_RESOURCEs may appear after device
> enumeration but before the late_initcall stage:
> 
> https://lore.kernel.org/r/20231019200110.GA1410324@bhelgaas/
> 
> Your patch will regress those platforms.
> 

Ok, thanks for the pointer. I was not aware of this issue.

> The proper solution is to make the resource files in sysfs static
> and call sysfs_update_group() from pci_sysfs_init().
> 
> Krzysztof has an old branch where he started working on this:
> 
> https://github.com/kwilczynski/linux/commits/kwilczynski/sysfs-static-resource-attributes/
> 

I had a chat with Krzysztof offline and he promised me that he will revive this
effort (thanks Krzysztof!).

- Mani

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