From: [EMAIL PROTECTED] Date: Fri, 10 Aug 2007 14:12:09 -0700 > From: Satyam Sharma <[EMAIL PROTECTED]> > > Based upon initial work by Keiichi Kii <[EMAIL PROTECTED]>. > > This patch introduces support for dynamic reconfiguration (adding, removing > and/or modifying parameters of netconsole targets at runtime) using a > userspace interface exported via configfs. Documentation is also updated > accordingly. > > Issues and brief design overview: > > (1) Kernel-initiated creation / destruction of kernel objects is not > possible with configfs -- the lifetimes of the "config items" is managed > exclusively from userspace. But netconsole must support boot/module > params too, and these are parsed in kernel and hence netpolls must be > setup from the kernel. Joel Becker suggested to separately manage the > lifetimes of the two kinds of netconsole_target objects -- those created > via configfs mkdir(2) from userspace and those specified from the > boot/module option string. This adds complexity and some redundancy here > and also means that boot/module param-created targets are not exposed > through the configfs namespace (and hence cannot be updated / destroyed > dynamically). However, this saves us from locking / refcounting > complexities that would need to be introduced in configfs to support > kernel-initiated item creation / destroy there. > > (2) In configfs, item creation takes place in the call chain of the > mkdir(2) syscall in the driver subsystem. If we used an ioctl(2) to > create / destroy objects from userspace, the special userspace program is > able to fill out the structure to be passed into the ioctl and hence > specify attributes such as local interface that are required at the time > we set up the netpoll. For configfs, this information is not available at > the time of mkdir(2). So, we keep all newly-created targets (via > configfs) disabled by default. The user is expected to set various > attributes appropriately (including the local network interface if > required) and then write(2) "1" to the "enabled" attribute. Thus, > netpoll_setup() is then called on the set parameters in the context of > _this_ write(2) on the "enabled" attribute itself. This design enables > the user to reconfigure existing netconsole targets at runtime to be > attached to newly-come-up interfaces that may not have existed when > netconsole was loaded or when the targets were actually created. All this > effectively enables us to get rid of custom ioctls. > > (3) Ultra-paranoid configfs attribute show() and store() operations, with > sanity and input range checking, using only safe string primitives, and > compliant with the recommendations in Documentation/filesystems/sysfs.txt. > > (4) A new function netpoll_print_options() is created in the netpoll API, > that just prints out the configured parameters for a netpoll structure. > netpoll_parse_options() is modified to use that and it is also exported to > be used from netconsole. > > Signed-off-by: Satyam Sharma <[EMAIL PROTECTED]> > Acked-by: Keiichi Kii <[EMAIL PROTECTED]> > Cc: Matt Mackall <[EMAIL PROTECTED]> > Cc: Joel Becker <[EMAIL PROTECTED]> > Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
This looks good to me, applied to net-2.6.24, thanks! - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
