From 7df7231d6a6b68b4b68fb4e38a4639997a208fd2 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 4 Mar 2024 21:33:07 -0800 Subject: [PATCH 1/4] tools: ynl: move the new line in NlMsg __repr__ We add the new line even if message has no error or extack, which leads to print(nl_msg) ending with two new lines. Reviewed-by: Donald Hunter Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller --- tools/net/ynl/lib/ynl.py | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py index ac55aa5a3083..92ade9105f31 100644 --- a/tools/net/ynl/lib/ynl.py +++ b/tools/net/ynl/lib/ynl.py @@ -213,11 +213,11 @@ class NlMsg: return self.nl_type def __repr__(self): - msg = f"nl_len = {self.nl_len} ({len(self.raw)}) nl_flags = 0x{self.nl_flags:x} nl_type = {self.nl_type}\n" + msg = f"nl_len = {self.nl_len} ({len(self.raw)}) nl_flags = 0x{self.nl_flags:x} nl_type = {self.nl_type}" if self.error: - msg += '\terror: ' + str(self.error) + msg += '\n\terror: ' + str(self.error) if self.extack: - msg += '\textack: ' + repr(self.extack) + msg += '\n\textack: ' + repr(self.extack) return msg From 7c93a88785dae6b61dc736b46594d088989e484b Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 4 Mar 2024 21:33:08 -0800 Subject: [PATCH 2/4] tools: ynl: allow setting recv() size 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 Reviewed-by: Donald Hunter Signed-off-by: David S. Miller --- tools/net/ynl/lib/ynl.py | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py index 92ade9105f31..c3ff5be33e4e 100644 --- a/tools/net/ynl/lib/ynl.py +++ b/tools/net/ynl/lib/ynl.py @@ -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: From a6a41521f95e5263a52ac79c02167a59ccc7183b Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 4 Mar 2024 21:33:09 -0800 Subject: [PATCH 3/4] tools: ynl: support debug printing messages For manual debug, allow printing the netlink level messages to stderr. Reviewed-by: Donald Hunter Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller --- tools/net/ynl/lib/ynl.py | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py index c3ff5be33e4e..239e22b7a85f 100644 --- a/tools/net/ynl/lib/ynl.py +++ b/tools/net/ynl/lib/ynl.py @@ -7,6 +7,7 @@ import random import socket import struct from struct import Struct +import sys import yaml import ipaddress import uuid @@ -420,6 +421,7 @@ class YnlFamily(SpecFamily): except KeyError: raise Exception(f"Family '{self.yaml['name']}' not supported by the kernel") + self._recv_dbg = False # 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. @@ -453,6 +455,17 @@ class YnlFamily(SpecFamily): self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_ADD_MEMBERSHIP, mcast_id) + def set_recv_dbg(self, enabled): + self._recv_dbg = enabled + + def _recv_dbg_print(self, reply, nl_msgs): + if not self._recv_dbg: + return + print("Recv: read", len(reply), "bytes,", + len(nl_msgs.msgs), "messages", file=sys.stderr) + for nl_msg in nl_msgs: + print(" ", nl_msg, file=sys.stderr) + def _encode_enum(self, attr_spec, value): enum = self.consts[attr_spec['enum']] if enum.type == 'flags' or attr_spec.get('enum-as-flags', False): @@ -819,6 +832,7 @@ class YnlFamily(SpecFamily): return nms = NlMsgs(reply) + self._recv_dbg_print(reply, nms) for nl_msg in nms: if nl_msg.error: print("Netlink error in ntf!?", os.strerror(-nl_msg.error)) @@ -871,6 +885,7 @@ class YnlFamily(SpecFamily): while not done: reply = self.sock.recv(self._recv_size) nms = NlMsgs(reply, attr_space=op.attr_set) + self._recv_dbg_print(reply, nms) for nl_msg in nms: if nl_msg.extack: self._decode_extack(msg, op, nl_msg.extack) From c0111878d45e3bb8779886fbf956b574bac8a3aa Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 4 Mar 2024 21:33:10 -0800 Subject: [PATCH 4/4] tools: ynl: add --dbg-small-recv for easier kernel testing Most "production" netlink clients use large buffers to make dump efficient, which means that handling of dump continuation in the kernel is not very well tested. Add an option for debugging / testing handling of dumps. It enables printing of extra netlink-level debug and lowers the recv() buffer size in one go. When used without any argument (--dbg-small-recv) it picks a very small default (4000), explicit size can be set, too (--dbg-small-recv 5000). Example: $ ./cli.py [...] --dbg-small-recv Recv: read 3712 bytes, 29 messages nl_len = 128 (112) nl_flags = 0x0 nl_type = 19 [...] nl_len = 128 (112) nl_flags = 0x0 nl_type = 19 Recv: read 3968 bytes, 31 messages nl_len = 128 (112) nl_flags = 0x0 nl_type = 19 [...] nl_len = 128 (112) nl_flags = 0x0 nl_type = 19 Recv: read 532 bytes, 5 messages nl_len = 128 (112) nl_flags = 0x0 nl_type = 19 [...] nl_len = 128 (112) nl_flags = 0x0 nl_type = 19 nl_len = 20 (4) nl_flags = 0x2 nl_type = 3 (the [...] are edits to shorten the commit message). Note that the first message of the dump is sized conservatively by the kernel. Signed-off-by: Jakub Kicinski Reviewed-by: Donald Hunter Signed-off-by: David S. Miller --- tools/net/ynl/cli.py | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/tools/net/ynl/cli.py b/tools/net/ynl/cli.py index 0f8239979670..e8a65fbc3698 100755 --- a/tools/net/ynl/cli.py +++ b/tools/net/ynl/cli.py @@ -38,6 +38,8 @@ def main(): const=Netlink.NLM_F_APPEND) parser.add_argument('--process-unknown', action=argparse.BooleanOptionalAction) parser.add_argument('--output-json', action='store_true') + parser.add_argument('--dbg-small-recv', default=0, const=4000, + action='store', nargs='?', type=int) args = parser.parse_args() def output(msg): @@ -53,7 +55,10 @@ def main(): if args.json_text: attrs = json.loads(args.json_text) - ynl = YnlFamily(args.spec, args.schema, args.process_unknown) + ynl = YnlFamily(args.spec, args.schema, args.process_unknown, + recv_size=args.dbg_small_recv) + if args.dbg_small_recv: + ynl.set_recv_dbg(True) if args.ntf: ynl.ntf_subscribe(args.ntf)