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@xxxxxxxxxxxxx>
---
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)
{
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