Re: [PATCH 0/2] target : replace netlink

[Douglas Gilbert <dougg@torque.net>]

FUJITA Tomonori wrote:
> The target code wrongly uses netlink to pass user-space buffer
> pointers. The kernel module sends SCSI commands to user space and
> receives responses from user-space daemon. So we need bi-directional,
> high-speed interface between user and kernel space. Currently, there
> isn't such interface in mainline. For example, mmapped packet and
> relayfs move data only from kernel to user space.

Good-bye netlink, another ioctl (or char driver)
replacement bites the dust. It looks like your
netlink replacement char driver has a lot in common
with the sg driver ...

I hope to present soon a version 4 of the SCSI generic
interface structure that will address some of
these concerns. [Basically an expanded version of
'struct sg_io_hdr' that includes bidirectional data
transfers and multi-protocol support.]

Doug Gilbert

> This patchset replaces netlink shared memory between kernel and user
> spaces. The user-space daemon and the kernel module create shared
> memory via mmap and use it like ring buffer (like mmapped packet
> does). The poll system call is used for notification from kernel to
> user space and the write system call is used for notification from
> user to kernel space. We use a simple approach so that we easily
> replace it if we find something better later on (or we implement a
> generic interface if necessary).
> 
> This patchset is against the scsi-target git tree and on the top of
> the following patch:
> 
> http://marc.theaimsgroup.com/?l=linux-scsi&m=114960851929878&w=2