Messages in this thread | | | Subject | Re: [PATCH 16/16] phy: phy-core: fix initcall level | From | Alexander Holler <> | Date | Fri, 18 Sep 2015 08:59:44 +0200 |
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Am 18.09.2015 um 08:16 schrieb Kishon Vijay Abraham I: > Hi, > > On Wednesday 26 August 2015 05:58 PM, Alexander Holler wrote: >> The phy-core has to be initialized before other dependent usb-drivers, >> otherwise a crash might occur. >> >> Currently phy_core_init() is called in the initcall-level device, which is >> the same level where most usb-drivers will end up. By luck this seemed to >> have been called most of the time before other usb-drivers without having >> been explicitly enforced. But if phy_core_init() is not called before a >> dependent driver, a null-pointer exception might occur (e.g. because the >> phy device class isn't registered). > > Did you actually face a problem? IIUC the modules get loaded based on > the drivers/Makefile order (unless the other modules are in a different > initcall table).
I had a problem while playing with a modified init-system (based on dependencies). So not an actual problem.
> IMHO the fix should be in the module that caused the crash. Change it to > use module_init?
The problem arises if the init-system ignores the link order and assumes all drivers in the same initcall level can be called without any special ordering. The problem might also appear if a driver changes its name, directory or position in file system. E.g. how to you make sure that a driver in staging will be linked after the phy-core? Actually this happens, but I would assume its by luck. I assume if staging would be renamed to 'beta-quality' a lot of stuff would actually fail because of the problem with the implicit link order.
Anyway, nothing which really has to be fixed. It's just a notice that maybe another initcall level of 'subsys' or something else before 'device' might be a better place for phy-core. I've chosen fs_sync instead of subsys because otherwise I would have had to look up if phy-core depends on another subsystem and therefore has to be initialized after subsys.
Regards,
Alexander Holler
> > Thanks > Kishon > >> >> To fix this, phy_core_init() is moved to the initcall-level fs (right >> before the standard initcall level device). >> >> Signed-off-by: Alexander Holler <holler@ahsoftware.de> >> --- >> drivers/phy/phy-core.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c >> index fc48fac..4945029 100644 >> --- a/drivers/phy/phy-core.c >> +++ b/drivers/phy/phy-core.c >> @@ -930,7 +930,7 @@ static int __init phy_core_init(void) >> >> return 0; >> } >> -module_init(phy_core_init); >> +fs_initcall_sync(phy_core_init); >> >> static void __exit phy_core_exit(void) >> { >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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