sched: Use lower layer cell limit with KISTLite

Instead of using INT_MAX as a write limit for KISTLite, use the lower layer
limit which is using the specialized num_cells_writeable() of the channel that
will down the line check the connection's outbuf and limit it to 32KB
(OR_CONN_HIGHWATER).

That way we don't take the chance of bloating the connection's outbuf and we
keep the cells in the circuit queue which our OOM handler can take care of,
not the outbuf.

Finally, this commit adds a log_debug() in the update socket information
function of KIST so we can get the socket information in debug.

Fixes #24671

Signed-off-by: David Goulet <dgoulet@torproject.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/changes/bug24671 b/changes/bug24671
new file mode 100644
index 0000000000..34d09e704d
--- /dev/null
+++ b/changes/bug24671
@@ -0,0 +1,6 @@
+  o Minor bugfixes (scheduler, KIST):
+    - Use a sane write limit for KISTLite when writing onto a connection
+      buffer instead of using INT_MAX and shoving as much as it can. Because
+      the OOM handler cleans up circuit queues, we are better off at keeping
+      them in that queue instead of the connection's buffer. Fixes bug 24671;
+      bugfix on 0.3.2.1-alpha.