Re: [GIT PULL] kdbus for 4.1-rc1

From: Richard Weinberger
Date: Thu Apr 30 2015 - 06:40:19 EST

Am 30.04.2015 um 12:19 schrieb Åukasz Stelmach:
> It was <2015-04-30 czw 11:12>, when Richard Weinberger wrote:
>> Am 30.04.2015 um 11:05 schrieb Åukasz Stelmach:
>>> Regardless, of initrd issues I feel there is a need of a local IPC
>>> that is more capable than UDS. Linus Torvalds is probably right that
>>> dbus-daemon is everything but effictient. I disagree, however, that
>>> it can be optimised and therefore solve *all* issues kdbus is trying
>>> to address. dbus-deamon, by design, can't some things. It can't
>>> transmitt large payloads without copying them. It can't be made
>>> race-free.
>> This is true.
>> But as long dbus-deamon is not optimized as much as possible there is
>> no reason to force push kdbus.
>> As soon dbus-deamon exploits all kernel interfaces as much it can and
>> it still needs work (may it performance or other stuff) we can think
>> of new kernel features which can help dbus-deamon.
> I may not be well informed about kernel interfaces, but there are some
> use cases no dbus-daemon optimisation can make work properly because of
> rece-conditons introduced by the user-space based message router.
> For example, a service can't aquire credentials of a client process that
> actually sent a request (it can, but it can't trust them). The service
> can't be protected by LSM on a bus that is driven by dbus-daemon. Yes,
> dbus-daemon, can check client's and srevice's labels and enforce a
> policy but it is going to be the daemon and not the LSM code in the
> kernel.

That's why I said we can think of new kernel features if they are needed.
But they current sink or swim approach of kdbus folks is also not the solution.
As I said, if dbus-daemon utilizes the kernel interface as much as possible we
can think of new features.


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