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>
Several devices have multiple independant RX queues per net
device, and some have a single interrupt doorbell for several
queues.
In either case, it's easier to support layouts like that if the
structure representing the poll is independant from the net
device itself.
The signature of the ->poll() call back goes from:
int foo_poll(struct net_device *dev, int *budget)
to
int foo_poll(struct napi_struct *napi, int budget)
The caller is returned the number of RX packets processed (or
the number of "NAPI credits" consumed if you want to get
abstract). The callee no longer messes around bumping
dev->quota, *budget, etc. because that is all handled in the
caller upon return.
The napi_struct is to be embedded in the device driver private data
structures.
Furthermore, it is the driver's responsibility to disable all NAPI
instances in it's ->stop() device close handler. Since the
napi_struct is privatized into the driver's private data structures,
only the driver knows how to get at all of the napi_struct instances
it may have per-device.
With lots of help and suggestions from Rusty Russell, Roland Dreier,
Michael Chan, Jeff Garzik, and Jamal Hadi Salim.
Bug fixes from Thomas Graf, Roland Dreier, Peter Zijlstra,
Joseph Fannin, Scott Wood, Hans J. Koch, and Michael Chan.
[ Ported to current tree and all drivers converted. Integrated
Stephen's follow-on kerneldoc additions, and restored poll_list
handling to the old style to fix mutual exclusion issues. -DaveM ]
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix up arch-specific work items where possible to use the new work_struct and
delayed_work structs.
Three places that enqueue bits of their stack and then return have been marked
with #error as this is not permitted.
Signed-Off-By: David Howells <dhowells@redhat.com>
As Steve left netpoll beast, hopefully not to return soon.
He noticed that the header was messy. He straightened it
up and polished it a little, then waved goodbye.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
The beast had a long and not very happy history. At one
point, a friend (netdump) had asked that he open up a little.
Well, the friend was long gone now, and the beast had
this dangling piece hanging (netpoll_queue).
It wasn't hard to stitch the netpoll_queue back in
where it belonged and make everything tidy.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
The netpoll beast was still not happy. If the beast got
clogged pipes, it tended to stare blankly off in space
for a long time.
The problem couldn't be completely fixed because the
beast talked with irq's disabled. But it could be made
less painful and shorter.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
When the netpoll beast got really busy, it tended to clog
things, so it stored them for later. But the beast was putting
all it's skb's in one basket. This was bad because maybe some
pipes were clogged and others were not.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
After looking harder, Steve noticed that the netpoll
beast leaked a little every time it shutdown for a nap.
Not a big leak, but a nuisance kind of thing.
He took out his refcount duct tape and patched the
leak. It was overkill since there was already other
locking in that area, but it looked clean and wouldn't
attract fleas.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
The netpoll system currently has a rx to tx path via:
netpoll_rx
__netpoll_rx
arp_reply
netpoll_send_skb
dev->hard_start_tx
This rx->tx loop places network drivers at risk of inadvertently causing a
deadlock or BUG halt by recursively trying to acquire a spinlock that is
used in both their rx and tx paths (this problem was origionally reported
to me in the 3c59x driver, which shares a spinlock between the
boomerang_interrupt and boomerang_start_xmit routines).
This patch breaks this loop, by queueing arp frames, so that they can be
responded to after all receive operations have been completed. Tested by
myself and the reported with successful results.
Specifically it was tested with netdump. Heres the BZ with details:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=194055
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
When netpoll is not being used, the macro that
defines the removed routing netpoll_poll_lock
defines the return as zero, but the real
routine returns a `void *`
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This fixes a race during initialization with the NAPI softirq
processing by using an RCU approach.
This race was discovered when refill_skbs() was added to
the setup code.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add limited retry logic to netpoll_send_skb
Each time we attempt to send, decrement our per-device retry counter.
On every successful send, we reset the counter.
We delay 50us between attempts with up to 20000 retries for a total of
1 second. After we've exhausted our retries, subsequent failed
attempts will try only once until reset by success.
Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch provides support for registering multiple netpoll clients to the
same network device. Only one of these clients may register an rx_hook,
however. In practice, this restriction has not been problematic. It is
worth mentioning, though, that the current design can be easily extended to
allow for the registration of multiple rx_hooks.
The basic idea of the patch is that the rx_np pointer in the netpoll_info
structure points to the struct netpoll that has rx_hook filled in. Aside
from this one case, there is no need for a pointer from the struct
net_device to an individual struct netpoll.
A lock is introduced to protect the setting and clearing of the np_rx
pointer. The pointer will only be cleared upon netpoll client module
removal, and the lock should be uncontested.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch introduces a netpoll_info structure, which the struct net_device
will now point to instead of pointing to a struct netpoll. The reason for
this is two-fold: 1) fields such as the rx_flags, poll_owner, and poll_lock
should be maintained per net_device, not per netpoll; and 2) this is a first
step in providing support for multiple netpoll clients to register against the
same net_device.
The struct netpoll is now pointed to by the netpoll_info structure. As
such, the previous behaviour of the code is preserved.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This trivial patch moves the assignment of poll_owner to -1 inside of
the lock. This fixes a potential SMP race in the code.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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!
Satyam Sharma