will never exit ngintr(), while there is some ready requests on the queue.
It was made years ago with hope of parallel queue processing by several
net threads. But even if we have several threads sometimes, we have no
rights to process queue in parallel as it will break original requests
serialization that is critically important for some setups.
Before this patch callback returned result of the last finished call chain.
Now it returns last nonzero result from all call chain results in this request.
As soon as this improvement gives reliable error reporting, it is now possible
to remove dirty workaround in ng_socket, made to return ENOBUFS error statuses
of request-response operations. That workaround was responsible for returning
ENOBUFS errors to completely unrelated requests working at the same time
on socket.
to avoid terrible unpredicted effects for netgraph operation of their
exhaustion while allocating control messages.
Add separate configurable 512 items limit for data items allocation
for DoS/overload protection.
Discussed with: julian
for that argument. This will allow DDB to detect the broad category of
reason why the debugger has been entered, which it can use for the
purposes of deciding which DDB script to run.
Assign approximate why values to all current consumers of the
kdb_enter() interface.
removing some copy&pasted code.
- Reduce copy and paste in ng_apply_item().
- Resurrect ng_send_fn() as a valid symbol, not a define.
Reviewed by: mav, julian
When item forwarded refence counter is incremented, when item
processed, counter decremented. When counter reaches zero,
apply handler is getting called.
Now it allows to report right connect() call status from user-level
at the right time.
Without it some errors may left unnoticed and unhandeled
that will lead to hooks left in half-connected state.
Reviewed by: julian@
Approved by: re (kensmith), glebius (mentor)
sysctl_handle_int is not sizeof the int type you want to export.
The type must always be an int or an unsigned int.
Remove the instances where a sizeof(variable) is passed to stop
people accidently cut and pasting these examples.
In a few places this was sysctl_handle_int was being used on 64 bit
types, which would truncate the value to be exported. In these
cases use sysctl_handle_quad to export them and change the format
to Q so that sysctl(1) can still print them.
for doing this job. This change will make it easy to migrate from using
spinning locks to adaptive ones.
Reviewed by: glebius, julian
Approved by: cognet (mentor)
from whoever has dequeued the item from the queue. Generally they have
no interest in the result, and even if it is called by the queuer, it
should still pretend that it was queued. The queuer should be assuming
that the call was queued and giving them the false confidence that they
are getting status leads to hard to find bugs.
Make it a void and remove all the code that tried to return status through it.
- Introduce ng_topo_mtx, a mutex to protect topology changes.
- In ng_destroy_node() protect with ng_topo_mtx the process
of checking and pointing at ng_deadnode. [1]
- In ng_con_part2() check that our peer is not a ng_deadnode,
and protect the check with ng_topo_mtx.
- Add KASSERTs to ng_acquire_read/write, to make more
understandible synopsis in case if called on ng_deadnode.
Reported by: Roselyn Lee [1]
- Introduce a new flags NGQF_QREADER and NGQF_QWRITER,
which tell how the item should be actually applied,
overriding NGQF_READER/NGQF_WRITER flags.
- Do not differ between pending reader or writer. Use only
one flag that is raised, when there are pending items.
- Schedule netgraph ISR in ng_queue_rw(), so that callers
do not need to do this job.
- Fix several comments.
Submitted by: julian
semantics, and then was reused for next node, it still would be applied
as writer again.
To fix the regression the decision is made never to alter item->el_flags
after the item has been allocated. This requires checking for overrides
both in ng_dequeue() and in ng_snd_item().
Details:
- Caller of the ng_apply_item() knows what is the current access to
node and specifies it to ng_apply_item(). The latter drops the
given access after item has beem applied.
- ng_dequeue() needs to be supplied with int pointer, where it stores
the obtained access on node.
- Check for node/hook access overrides in ng_dequeue().
times consequently, without checking whether callout has been serviced
or not. (ng_pptpgre and ng_ppp were catched in this behavior).
- In ng_callout() save old item before calling callout_reset(). If the
latter has returned 1, then free this item.
- In ng_uncallout() clear c->c_arg.
Problem reported by: Alexandre Kardanev
either reader or writer flag on item in the function, that
allocates the item. Do not modify these flags when item is
applied or queued.
The only exceptions are node and hook overrides - they can
change item flags to writer.
At the end of ng_snd_item(), node queue is processed. In certain
netgraph setups deep recursive calls can occur.
For example this happens, when two nodes are connected and can send
items to each other in both directions. If, for some reason, both nodes
have a lot of items in their queues, then the processing thread will
recurse between these two nodes, delivering items left and right, going
deeper in the stack. Other setups can suffer from deep recursion, too.
The following factors can influence risk of deep netgraph call:
- periodical write-access events on node
- combination of slow link and fast one in one graph
- net.inet.ip.fastforwarding
Changes made:
- In ng_acquire_{read,write}() do not dequeue another item. Instead,
call ng_setisr() for this node.
- At the end of ng_snd_item(), do not process queue. Call ng_setisr(),
if there are any dequeueable items on node queue.
- In ng_setisr() narrow worklist mutex holding.
- In ng_setisr() assert queue mutex.
Theoretically, the first two changes should negatively affect performance.
To check this, some profiling was made:
1) In general real tasks, no noticable performance difference was found.
2) The following test was made: two multithreaded nodes and one
single-threaded were connected into a ring. A large queues of packets
were sent around this ring. Time to pass the ring N times was measured.
This is a very vacuous test: no items/mbufs are allocated, no upcalls or
downcalls outside of netgraph. It doesn't represent a real load, it is
a stress test for ng_acquire_{read,write}() and item queueing functions.
Surprisingly, the performance impact was positive! New code is 13% faster
on UP and 17% faster on SMP, in this particular test.
The problem was originally found, described, analyzed and original patch
was written by Roselyn Lee from Vernier Networks. Thanks!
Submitted by: Roselyn Lee <rosel verniernetworks com>
