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tools: ynl: allow setting recv() size

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Make the size of the buffer we use for recv() configurable.
The details of the buffer sizing in netlink are somewhat
arcane, we could spend a lot of time polishing this API.
Let's just leave some hopefully helpful comments for now.
This is a for-developers-only feature, anyway.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski 2024-03-04 21:33:08 -08:00 committed by David S. Miller
parent 7df7231d6a
commit 7c93a88785
1 changed files with 18 additions and 3 deletions
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21
tools/net/ynl/lib/ynl.py
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@ -84,6 +84,10 @@ class NlError(Exception):
return f"Netlink error: {os.strerror(-self.nl_msg.error)}\n{self.nl_msg}"
class ConfigError(Exception):
pass
class NlAttr:
ScalarFormat = namedtuple('ScalarFormat', ['native', 'big', 'little'])
type_formats = {
@ -400,7 +404,8 @@ class SpaceAttrs:
class YnlFamily(SpecFamily):
def __init__(self, def_path, schema=None, process_unknown=False):
def __init__(self, def_path, schema=None, process_unknown=False,
recv_size=0):
super().__init__(def_path, schema)
self.include_raw = False
@ -415,6 +420,16 @@ class YnlFamily(SpecFamily):
except KeyError:
raise Exception(f"Family '{self.yaml['name']}' not supported by the kernel")
# Note that netlink will use conservative (min) message size for
# the first dump recv() on the socket, our setting will only matter
# from the second recv() on.
self._recv_size = recv_size if recv_size else 131072
# Netlink will always allocate at least PAGE_SIZE - sizeof(skb_shinfo)
# for a message, so smaller receive sizes will lead to truncation.
# Note that the min size for other families may be larger than 4k!
if self._recv_size < 4000:
raise ConfigError()
self.sock = socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, self.nlproto.proto_num)
self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_CAP_ACK, 1)
self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_EXT_ACK, 1)
@ -799,7 +814,7 @@ class YnlFamily(SpecFamily):
def check_ntf(self):
while True:
try:
reply = self.sock.recv(128 * 1024, socket.MSG_DONTWAIT)
reply = self.sock.recv(self._recv_size, socket.MSG_DONTWAIT)
except BlockingIOError:
return
@ -854,7 +869,7 @@ class YnlFamily(SpecFamily):
done = False
rsp = []
while not done:
reply = self.sock.recv(128 * 1024)
reply = self.sock.recv(self._recv_size)
nms = NlMsgs(reply, attr_space=op.attr_set)
for nl_msg in nms:
if nl_msg.extack: