Prevent PCI driver registration failure oopsing
PATCH 1/1 Prevent PCI driver registration failure oopsing
Greg,
As discussed about six or so months ago, we agreed to hold off this patch until fairly late, due to its ability to catch duplicate PCI driver names. Please note that I haven't attempted to reproduce the problem with recent kernels, and that all ARM kernel patches released since then have had this patch in.
I'm guessing this will actually be 2.6.1 material since it probably doesn't show for PCI drivers which are part of the kernel tree.
If pci_register_driver fails, the register the PCI driver structure will not be registered with the driver model. pci_register_driver returns with negative value, and we then attempt to unregister the driver structure. This leads to an oops in the driver model.
The driver model does not return the number of devices it successfully bound the driver to, and neither does pci_register_driver() return this information.
Therefore, all of the code below is redundant.
(There's a little redundancy left in drivers/pci/pci-driver.c but it is harmless unlike this block.)
include/linux/pci.h +1 -20
@@ -768,26 +768,7 @@ {int rc =pci_register_driver (drv); -if (rc >0 ) -return 0 ; - -/* iff CONFIG_HOTPLUG and built into kernel, we should -* leave the driver around for future hotplug events. -* For the module case, a hotplug daemon of some sort -* should load a module in response to an insert event. */ -#if defined(CONFIG_HOTPLUG ) && !defined(MODULE ) -if (rc ==0 ) -return 0 ; -#else -if (rc ==0 ) - rc = -ENODEV ; -#endif - -/* if we get here, we need to clean up pci driver instance -* and return some sort of error */ -pci_unregister_driver (drv); - -return rc; +return rc <0 ? :0 ; }/*
Signature · 4 lines
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial coreQuoted 17 lines · Russell King
include/linux/pci.h +0
-11@@ -768,26 +768,7 @@ {int rc =pci_register_driver (drv); -if (rc >0 ) -return 0 ; - -/* iff CONFIG_HOTPLUG and built into kernel, we should -* leave the driver around for future hotplug events. -* For the module case, a hotplug daemon of some sort -* should load a module in response to an insert event. */ -#if defined(CONFIG_HOTPLUG ) && !defined(MODULE ) -if (rc ==0 ) -return 0 ; -#else
include/linux/pci.h line 771
Quoted 10 lines
include/linux/pci.h +1
-9-if (rc ==0 ) - rc = -ENODEV ; -#endif - -/* if we get here, we need to clean up pci driver instance -* and return some sort of error */ -pci_unregister_driver (drv); - -return rc; +return rc <0 ? :0 ;
Are you sure you want to return 1 if rc < 0?
Andreas.
Signature · 4 lines
Andreas Schwab, SuSE Labs, [email protected] SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 Nürnberg Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different."
Quoted 4 lines · Andreas Schwab
Review
Quoted 1 line · Russell King
(quoted diff) +1
-0+ return rc < 0 ? : 0;Are you sure you want to return 1 if rc < 0?
Argh. Definitely not. Thanks for spotting that.
include/linux/pci.h +1 -20
@@ -768,26 +768,7 @@ {int rc =pci_register_driver (drv); -if (rc >0 ) -return 0 ; - -/* iff CONFIG_HOTPLUG and built into kernel, we should -* leave the driver around for future hotplug events. -* For the module case, a hotplug daemon of some sort -* should load a module in response to an insert event. */ -#if defined(CONFIG_HOTPLUG ) && !defined(MODULE ) -if (rc ==0 ) -return 0 ; -#else -if (rc ==0 ) - rc = -ENODEV ; -#endif - -/* if we get here, we need to clean up pci driver instance -* and return some sort of error */ -pci_unregister_driver (drv); - -return rc; +return rc <0 ? rc :0 ; }/*
Signature · 4 lines
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial coreinclude/linux/pci.h
Quoted 10 lines · Russell King
Quoted 4 lines · Andreas Schwab
Review
Quoted 1 line · Russell King
(quoted diff) +1
-0+ return rc < 0 ? : 0;Are you sure you want to return 1 if rc < 0?
Argh. Definitely not. Thanks for spotting that.
include/linux/pci.h +0
-0
Thanks, I've applied this and will send it to Linus when 2.6.0 is out.
greg k-h