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* [NET] netconsole: Support dynamic reconfiguration using configfsSatyam Sharma2007-10-101-0/+68
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Based upon initial work by Keiichi Kii <k-keiichi@bx.jp.nec.com>. 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 <satyam@infradead.org> Acked-by: Keiichi Kii <k-keiichi@bx.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* [NET] netconsole: Support multiple logging targetsSatyam Sharma2007-10-101-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Based upon initial work by Keiichi Kii <k-keiichi@bx.jp.nec.com>. This patch introduces support for multiple targets, independent of CONFIG_NETCONSOLE_DYNAMIC -- this is useful even in the default case and (including the infrastructure introduced in previous patches) doesn't really add too many bytes to module text. All the complexity (and size) comes with the dynamic reconfigurability / userspace interface patch, and so it's plausible users may want to keep this enabled but that disabled (say to avoid a dependency on CONFIG_CONFIGFS_FS too). Also update documentation to mention the use of ";" separator to specify multiple logging targets in the boot/module option string. Brief overview: We maintain a target_list (and corresponding lock). Get rid of the static "default_target" and introduce allocation and release functions for our netconsole_target objects (but keeping sure to preserve previous behaviour such as default values). During init_netconsole(), ";" is used as the separator to identify multiple target specifications in the boot/module option string. The target specifications are parsed and netpolls setup. During exit, the target_list is torn down and all items released. Signed-off-by: Satyam Sharma <satyam@infradead.org> Signed-off-by: Keiichi Kii <k-keiichi@bx.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* [NET] netconsole: Add some useful tips to documentationSatyam Sharma2007-10-101-0/+25
| | | | | | | | | | | | | | Based upon initial work by Keiichi Kii <k-keiichi@bx.jp.nec.com>. Add some useful general-purpose tips. Also suggest solution for the frequent problem of console loglevel set too low numerically (i.e. for high priority messages only) on the sender. Signed-off-by: Satyam Sharma <satyam@infradead.org> Acked-by: Keiichi Kii <k-keiichi@bx.jp.nec.com> Acked-by: Matt Mackall <mpm@selenic.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* Fix "can not" in Documentation and KconfigMatt LaPlante2006-10-031-1/+1
| | | | | | | | | | | Randy brought it to my attention that in proper english "can not" should always be written "cannot". I donot see any reason to argue, even if I mightnot understand why this rule exists. This patch fixes "can not" in several Documentation files as well as three Kconfigs. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds2005-04-161-0/+57
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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