1
linux/drivers
Satyam Sharma 0bcc181618 [NET] netconsole: Support dynamic reconfiguration using configfs
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>
2007-10-10 16:48:06 -07:00
..
acorn/char Remove the arm26 port 2007-07-31 15:39:39 -07:00
acpi ACPI: CONFIG_ACPI_SLEEP=n power off regression in 2.6.23-rc8 (NOT in rc7) 2007-09-25 17:58:52 -04:00
amba
ata sata_mv: correct S/G table limits 2007-10-09 12:38:26 -07:00
atm Add some help texts to recently-introduced kconfig items 2007-08-18 09:52:50 -07:00
auxdisplay cfag12864b fix 2007-08-22 19:52:46 -07:00
base Driver core: fix SYSF_DEPRECATED breakage for nested classdevs 2007-10-07 16:42:22 -07:00
block Fix "Fix DAC960 driver on machines which don't support 64-bit DMA" 2007-09-19 11:24:16 -07:00
bluetooth [Bluetooth] Add missing stat.byte_rx counter modification 2007-09-09 08:39:27 +02:00
cdrom cdrom_open() forgets to unlock on -EROFS failure exits 2007-09-26 08:20:44 +02:00
char Correct Makefile rule for generating custom keymap 2007-10-08 16:06:51 -07:00
clocksource
connector
cpufreq
crypto Add some help texts to recently-introduced kconfig items 2007-08-18 09:52:50 -07:00
dio
dma [IOAT]: ioatdma needs to to play nice in a multi-dma-client world 2007-08-26 18:35:40 -07:00
edac drivers/edac: fix e752x correct return code 2007-09-11 17:21:19 -07:00
eisa
fc4
firewire firewire: point to migration document 2007-10-07 13:48:41 +02:00
firmware
hid Add some help texts to recently-introduced kconfig items 2007-08-18 09:52:50 -07:00
hwmon hwmon: End of I/O region off-by-one 2007-09-09 10:38:37 -04:00
i2c i2c-algo-bit: Read block data bugfix 2007-09-09 22:29:14 +02:00
ide Fix non-terminated PCI match table in PowerMac IDE 2007-10-06 09:32:56 -07:00
ieee1394 ieee1394: ohci1394: fix initialization if built non-modular 2007-09-20 21:19:45 +02:00
infiniband [NET]: Make NAPI polling independent of struct net_device objects. 2007-10-10 16:47:45 -07:00
input Input: xpad - fix dependancy on LEDS class 2007-09-28 15:38:12 -07:00
isdn ISDN: Fix data access out of array bounds 2007-10-08 13:01:21 -07:00
kvm KVM: Fix virtualization menu help text 2007-09-22 12:55:18 -07:00
leds
lguest fix modules oopsing in lguest guests 2007-09-25 08:51:04 -07:00
macintosh [POWERPC] Fix undefined reference to device_power_up/resume 2007-08-25 16:58:27 +10:00
mca
md raid5: fix 2 bugs in ops_complete_biofill 2007-09-24 13:23:35 -07:00
media V4L/DVB (6052): ivtv: fix udma yuv bug 2007-09-30 10:31:34 -03:00
message Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6 2007-08-06 17:48:34 -07:00
mfd
misc Pull thinkpad into release branch 2007-09-17 00:58:40 -04:00
mmc bug in AT91 MCI suspend routines 2007-09-11 17:21:51 +02:00
mtd pci: fix unterminated pci_device_id lists 2007-09-19 11:24:17 -07:00
net [NET] netconsole: Support dynamic reconfiguration using configfs 2007-10-10 16:48:06 -07:00
nubus
of
oprofile
parisc
parport parport_pc locking fix 2007-07-31 15:39:37 -07:00
pci Fix bogus PCI quirk for e100 2007-09-28 16:21:10 -07:00
pcmcia pcmcia: give socket time to power down 2007-07-31 15:39:38 -07:00
pnp PNP: remove SMCf010 quirk 2007-09-11 17:21:19 -07:00
power [PATCH] missing null termination in power supply uevent 2007-09-21 01:22:23 +04:00
ps3
rapidio
rtc rtc: rtc-ds1553.c should use resource_size_t for base address 2007-09-19 11:24:17 -07:00
s390 Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6 2007-09-11 07:46:09 -07:00
sbus Videopix Frame Grabber: Fix unreleased lock in vfc_debug() 2007-07-31 15:39:43 -07:00
scsi [SCSI] megaraid_old: fix READ_CAPACITY 2007-10-04 12:08:49 -04:00
serial Add manufacturer and card id of teltonica pcmcia modems 2007-10-07 16:28:43 -07:00
sh
sn
spi spi_mpc83xx: hang fix 2007-09-11 17:21:19 -07:00
tc
telephony
uio
usb Revert "usb-storage: implement autosuspend" 2007-09-13 06:01:24 -07:00
video intelfb: Fix bug in DPLL disable 2007-09-19 11:24:18 -07:00
w1 missing null termination in one wire uevent 2007-09-25 08:51:04 -07:00
xen xenbus_xs.c: fix a use-after-free 2007-07-26 11:35:17 -07:00
zorro zorro: Make sysfs config attribute read-only 2007-08-22 19:52:45 -07:00
Kconfig
Makefile [WATCHDOG] Fix pcwd_init_module crash 2007-07-29 18:58:39 +00:00