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nvme-stas/staslib/udev.py
Daniel Baumann ca2ec6771a
Merging upstream version 2.3~rc1. 
Signed-off-by: Daniel Baumann <daniel@debian.org>
2025-02-16 12:53:58 +01:00

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Python
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# Copyright (c) 2022, Dell Inc. or its subsidiaries. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
# See the LICENSE file for details.
#
# This file is part of NVMe STorage Appliance Services (nvme-stas).
#
# Authors: Martin Belanger <Martin.Belanger@dell.com>
#
'''This module provides functions to access nvme devices using the pyudev module'''
import os
import time
import logging
import pyudev
from gi.repository import GLib
from staslib import defs, iputil, trid
# ******************************************************************************
class Udev:
'''@brief Udev event monitor. Provide a way to register for udev events.
WARNING: THE singleton.Singleton PATTERN CANNOT BE USED WITH THIS CLASS.
IT INTERFERES WITH THE pyudev INTERNALS, WHICH CAUSES OBJECT CLEAN UP TO FAIL.
'''
def __init__(self):
self._log_event_soak_time = 0
self._log_event_count = 0
self._device_event_registry = dict()
self._action_event_registry = dict()
self._context = pyudev.Context()
self._monitor = pyudev.Monitor.from_netlink(self._context)
self._monitor.filter_by(subsystem='nvme')
self._event_source = GLib.io_add_watch(
self._monitor.fileno(),
GLib.PRIORITY_HIGH,
GLib.IO_IN,
self._process_udev_event,
)
self._monitor.start()
def release_resources(self):
'''Release all resources used by this object'''
if self._event_source is not None:
GLib.source_remove(self._event_source)
if self._monitor is not None:
self._monitor.remove_filter()
self._event_source = None
self._monitor = None
self._context = None
self._device_event_registry = None
self._action_event_registry = None
def get_nvme_device(self, sys_name):
'''@brief Get the udev device object associated with an nvme device.
@param sys_name: The device system name (e.g. 'nvme1')
@return A pyudev.device._device.Device object
'''
device_node = os.path.join('/dev', sys_name)
try:
return pyudev.Devices.from_device_file(self._context, device_node)
except pyudev.DeviceNotFoundByFileError as ex:
logging.error("Udev.get_nvme_device() - Error: %s", ex)
return None
def is_action_cback_registered(self, action: str, user_cback):
'''Returns True if @user_cback is registered for @action. False otherwise.
@param action: one of 'add', 'remove', 'change'.
@param user_cback: A callback function with this signature: cback(udev_obj)
'''
return user_cback in self._action_event_registry.get(action, set())
def register_for_action_events(self, action: str, user_cback):
'''@brief Register a callback function to be called when udev events
for a specific action are received.
@param action: one of 'add', 'remove', 'change'.
'''
self._action_event_registry.setdefault(action, set()).add(user_cback)
def unregister_for_action_events(self, action: str, user_cback):
'''@brief The opposite of register_for_action_events()'''
try:
self._action_event_registry.get(action, set()).remove(user_cback)
except KeyError: # Raise if user_cback already removed
pass
def register_for_device_events(self, sys_name: str, user_cback):
'''@brief Register a callback function to be called when udev events
are received for a specific nvme device.
@param sys_name: The device system name (e.g. 'nvme1')
'''
if sys_name:
self._device_event_registry[sys_name] = user_cback
def unregister_for_device_events(self, user_cback):
'''@brief The opposite of register_for_device_events()'''
entries = list(self._device_event_registry.items())
for sys_name, _user_cback in entries:
if user_cback == _user_cback:
self._device_event_registry.pop(sys_name, None)
break
def get_attributes(self, sys_name: str, attr_ids) -> dict:
'''@brief Get all the attributes associated with device @sys_name'''
attrs = {attr_id: '' for attr_id in attr_ids}
if sys_name and sys_name != 'nvme?':
udev = self.get_nvme_device(sys_name)
if udev is not None:
for attr_id in attr_ids:
try:
value = udev.attributes.asstring(attr_id).strip()
attrs[attr_id] = '' if value == '(efault)' else value
except Exception: # pylint: disable=broad-except
pass
return attrs
@staticmethod
def is_dc_device(device):
'''@brief check whether device refers to a Discovery Controller'''
subsysnqn = device.attributes.get('subsysnqn')
if subsysnqn is not None and subsysnqn.decode() == defs.WELL_KNOWN_DISC_NQN:
return True
# Note: Prior to 5.18 linux didn't expose the cntrltype through
# the sysfs. So, this may return None on older kernels.
cntrltype = device.attributes.get('cntrltype')
if cntrltype is not None and cntrltype.decode() == 'discovery':
return True
# Imply Discovery controller based on the absence of children.
# Discovery Controllers have no children devices
if len(list(device.children)) == 0:
return True
return False
@staticmethod
def is_ioc_device(device):
'''@brief check whether device refers to an I/O Controller'''
# Note: Prior to 5.18 linux didn't expose the cntrltype through
# the sysfs. So, this may return None on older kernels.
cntrltype = device.attributes.get('cntrltype')
if cntrltype is not None and cntrltype.decode() == 'io':
return True
# Imply I/O controller based on the presence of children.
# I/O Controllers have children devices
if len(list(device.children)) != 0:
return True
return False
@staticmethod
def _cid_matches_tcp_tid_legacy(tid, cid): # pylint: disable=too-many-return-statements,too-many-branches
'''On kernels older than 6.1, the src_addr parameter is not available
from the sysfs. Therefore, we need to infer a match based on other
parameters. And there are a few cases where we're simply not sure
whether an existing connection (cid) matches the candidate
connection (tid).
'''
cid_host_iface = cid['host-iface']
cid_host_traddr = iputil.get_ipaddress_obj(cid['host-traddr'], ipv4_mapped_convert=True)
if not cid_host_iface: # cid.host_iface is undefined
if not cid_host_traddr: # cid.host_traddr is undefined
# When the existing cid.src_addr, cid.host_traddr, and cid.host_iface
# are all undefined (which can only happen on kernels prior to 6.1),
# we can't know for sure on which interface an existing connection
# was made. In this case, we can only declare a match if both
# tid.host_iface and tid.host_traddr are undefined as well.
logging.debug(
'Udev._cid_matches_tcp_tid_legacy() - cid=%s, tid=%s - Not enough info. Assume "match" but this could be wrong.',
cid,
tid,
)
return True
# cid.host_traddr is defined. If tid.host_traddr is also
# defined, then it must match the existing cid.host_traddr.
if tid.host_traddr:
tid_host_traddr = iputil.get_ipaddress_obj(tid.host_traddr, ipv4_mapped_convert=True)
if tid_host_traddr != cid_host_traddr:
return False
# If tid.host_iface is defined, then the interface where
# the connection is located must match. If tid.host_iface
# is not defined, then we don't really care on which
# interface the connection was made and we can skip this test.
if tid.host_iface:
# With the existing cid.host_traddr, we can find the
# interface of the exisiting connection.
connection_iface = iputil.get_interface(str(cid_host_traddr))
if tid.host_iface != connection_iface:
return False
return True
# cid.host_iface is defined
if not cid_host_traddr: # cid.host_traddr is undefined
if tid.host_iface and tid.host_iface != cid_host_iface:
return False
if tid.host_traddr:
# It's impossible to tell the existing connection source
# address. So, we can't tell if it matches tid.host_traddr.
# However, if the existing host_iface has only one source
# address assigned to it, we can assume that the source
# address used for the existing connection is that address.
if_addrs = iputil.net_if_addrs().get(cid_host_iface, {4: [], 6: []})
tid_host_traddr = iputil.get_ipaddress_obj(tid.host_traddr, ipv4_mapped_convert=True)
source_addrs = if_addrs[tid_host_traddr.version]
if len(source_addrs) != 1:
return False
src_addr0 = iputil.get_ipaddress_obj(source_addrs[0], ipv4_mapped_convert=True)
if src_addr0 != tid_host_traddr:
return False
return True
# cid.host_traddr is defined
if tid.host_iface and tid.host_iface != cid_host_iface:
return False
if tid.host_traddr:
tid_host_traddr = iputil.get_ipaddress_obj(tid.host_traddr, ipv4_mapped_convert=True)
if tid_host_traddr != cid_host_traddr:
return False
return True
@staticmethod
def _cid_matches_tid(tid, cid): # pylint: disable=too-many-return-statements,too-many-branches
'''Check if existing controller's cid matches candidate controller's tid.
@param cid: The Connection ID of an existing controller (from the sysfs).
@param tid: The Transport ID of a candidate controller.
We're trying to find if an existing connection (specified by cid) can
be re-used for the candidate controller (specified by tid).
We do not have a match if the candidate's tid.transport, tid.traddr,
tid.trsvcid, and tid.subsysnqn are not identical to those of the cid.
These 4 parameters are mandatory for a match.
The tid.host_traddr and tid.host_iface depend on the transport type.
These parameters may not apply or have a different syntax/meaning
depending on the transport type.
For TCP only:
With regards to the candidate's tid.host_traddr and tid.host_iface,
if those are defined but do not match the existing cid.host_traddr
and cid.host_iface, we may still be able to find a match by taking
the existing cid.src_addr into consideration since that parameter
identifies the actual source address of the connection and therefore
can be used to infer the interface of the connection. However, the
cid.src_addr can only be read from the sysfs starting with kernel
6.1.
'''
# 'transport', 'traddr', 'trsvcid', and 'subsysnqn' must exactly match.
if cid['transport'] != tid.transport or cid['trsvcid'] != tid.trsvcid or cid['subsysnqn'] != tid.subsysnqn:
return False
if tid.transport in ('tcp', 'rdma'):
# Need to convert to ipaddress objects to properly
# handle all variations of IPv6 addresses.
tid_traddr = iputil.get_ipaddress_obj(tid.traddr, ipv4_mapped_convert=True)
cid_traddr = iputil.get_ipaddress_obj(cid['traddr'], ipv4_mapped_convert=True)
else:
cid_traddr = cid['traddr']
tid_traddr = tid.traddr
if cid_traddr != tid_traddr:
return False
# We need to know the type of transport to compare 'host-traddr' and
# 'host-iface'. These parameters don't apply to all transport types
# and may have a different meaning/syntax.
if tid.transport == 'tcp':
if tid.host_traddr or tid.host_iface:
src_addr = iputil.get_ipaddress_obj(cid['src-addr'], ipv4_mapped_convert=True)
if not src_addr:
# For legacy kernels (i.e. older than 6.1), the existing cid.src_addr
# is always undefined. We need to use advanced logic to determine
# whether cid and tid match.
return Udev._cid_matches_tcp_tid_legacy(tid, cid)
# The existing controller's cid.src_addr is always defined for kernel
# 6.1 and later. We can use the existing controller's cid.src_addr to
# find the interface on which the connection was made and therefore
# match it to the candidate's tid.host_iface. And the cid.src_addr
# can also be used to match the candidate's tid.host_traddr.
if tid.host_traddr:
tid_host_traddr = iputil.get_ipaddress_obj(tid.host_traddr, ipv4_mapped_convert=True)
if tid_host_traddr != src_addr:
return False
# host-iface is an optional tcp-only parameter.
if tid.host_iface and tid.host_iface != iputil.get_interface(str(src_addr)):
return False
elif tid.transport == 'fc':
# host-traddr is mandatory for FC.
if tid.host_traddr != cid['host-traddr']:
return False
elif tid.transport == 'rdma':
# host-traddr is optional for RDMA and is expressed as an IP address.
if tid.host_traddr:
tid_host_traddr = iputil.get_ipaddress_obj(tid.host_traddr, ipv4_mapped_convert=True)
cid_host_traddr = iputil.get_ipaddress_obj(cid['host-traddr'], ipv4_mapped_convert=True)
if tid_host_traddr != cid_host_traddr:
return False
return True
def find_nvme_dc_device(self, tid):
'''@brief Find the nvme device associated with the specified
Discovery Controller.
@return The device if a match is found, None otherwise.
'''
for device in self._context.list_devices(
subsystem='nvme', NVME_TRADDR=tid.traddr, NVME_TRSVCID=tid.trsvcid, NVME_TRTYPE=tid.transport
):
if not self.is_dc_device(device):
continue
cid = self.get_cid(device)
if not self._cid_matches_tid(tid, cid):
continue
return device
return None
def find_nvme_ioc_device(self, tid):
'''@brief Find the nvme device associated with the specified
I/O Controller.
@return The device if a match is found, None otherwise.
'''
for device in self._context.list_devices(
subsystem='nvme', NVME_TRADDR=tid.traddr, NVME_TRSVCID=tid.trsvcid, NVME_TRTYPE=tid.transport
):
if not self.is_ioc_device(device):
continue
cid = self.get_cid(device)
if not self._cid_matches_tid(tid, cid):
continue
return device
return None
def get_nvme_ioc_tids(self, transports):
'''@brief Find all the I/O controller nvme devices in the system.
@return A list of pyudev.device._device.Device objects
'''
tids = []
for device in self._context.list_devices(subsystem='nvme'):
if device.properties.get('NVME_TRTYPE', '') not in transports:
continue
if not self.is_ioc_device(device):
continue
tids.append(self.get_tid(device))
return tids
def _process_udev_event(self, event_source, condition): # pylint: disable=unused-argument
if condition == GLib.IO_IN:
event_count = 0
while True:
try:
device = self._monitor.poll(timeout=0)
except EnvironmentError as ex:
device = None
# This event seems to happen in bursts. So, let's suppress
# logging for 2 seconds to avoid filling the syslog.
self._log_event_count += 1
now = time.time()
if now > self._log_event_soak_time:
logging.debug('Udev._process_udev_event() - %s [%s]', ex, self._log_event_count)
self._log_event_soak_time = now + 2
self._log_event_count = 0
if device is None:
break
event_count += 1
self._device_event(device, event_count)
return GLib.SOURCE_CONTINUE
@staticmethod
def __cback_names(action_cbacks, device_cback):
names = []
for cback in action_cbacks:
names.append(cback.__name__ + '()')
if device_cback:
names.append(device_cback.__name__ + '()')
return names
def _device_event(self, device, event_count):
action_cbacks = self._action_event_registry.get(device.action, set())
device_cback = self._device_event_registry.get(device.sys_name, None)
logging.debug(
'Udev._device_event() - %-8s %-6s %-8s %s',
f'{device.sys_name}:',
device.action,
f'{event_count:2}:{device.sequence_number}',
self.__cback_names(action_cbacks, device_cback),
)
for action_cback in action_cbacks:
GLib.idle_add(action_cback, device)
if device_cback is not None:
GLib.idle_add(device_cback, device)
@staticmethod
def _get_property(device, prop, default=''):
prop = device.properties.get(prop, default)
return '' if prop.lower() == 'none' else prop
@staticmethod
def _get_attribute(device, attr_id, default=''):
try:
attr = device.attributes.asstring(attr_id).strip()
except Exception: # pylint: disable=broad-except
attr = default
return '' if attr.lower() == 'none' else attr
@staticmethod
def get_key_from_attr(device, attr, key, delim=','):
'''Get attribute specified by attr, which is composed of key=value pairs.
Then return the value associated with key.
@param device: The Device object
@param attr: The device's attribute to get
@param key: The key to look for in the attribute
@param delim: Delimiter used between key=value pairs.
@example:
"address" attribute contains "trtype=tcp,traddr=10.10.1.100,trsvcid=4420,host_traddr=10.10.1.50"
'''
attr_str = Udev._get_attribute(device, attr)
if not attr_str:
return ''
if key[-1] != '=':
key += '='
start = attr_str.find(key)
if start < 0:
return ''
start += len(key)
end = attr_str.find(delim, start)
if end < 0:
return attr_str[start:]
return attr_str[start:end]
@staticmethod
def get_tid(device):
'''@brief return the Transport ID associated with a udev device'''
cid = Udev.get_cid(device)
if cid['transport'] == 'tcp':
src_addr = cid['src-addr']
if not cid['host-iface'] and src_addr:
# We'll try to find the interface from the source address on
# the connection. Only available if kernel exposes the source
# address (src_addr) in the "address" attribute.
cid['host-iface'] = iputil.get_interface(src_addr)
return trid.TID(cid)
@staticmethod
def get_cid(device):
'''@brief return the Connection ID associated with a udev device'''
cid = {
'transport': Udev._get_property(device, 'NVME_TRTYPE'),
'traddr': Udev._get_property(device, 'NVME_TRADDR'),
'trsvcid': Udev._get_property(device, 'NVME_TRSVCID'),
'host-traddr': Udev._get_property(device, 'NVME_HOST_TRADDR'),
'host-iface': Udev._get_property(device, 'NVME_HOST_IFACE'),
'subsysnqn': Udev._get_attribute(device, 'subsysnqn'),
'src-addr': Udev.get_key_from_attr(device, 'address', 'src_addr='),
}
return cid
UDEV = Udev() # Singleton
def shutdown():
'''Destroy the UDEV singleton'''
global UDEV # pylint: disable=global-statement,global-variable-not-assigned
UDEV.release_resources()
del UDEV
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