qemu-e2k/scripts/qemugdb/aio.py

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gdb command: qemu handlers A new gdb commands are added: qemu handlers That dumps an AioContext list (by default qemu_aio_context) possibly including a backtrace for cases it knows about (with the verbose option). Intended to help find why something is hanging waiting for IO. Use 'qemu handlers --verbose iohandler_ctx' to find out why your incoming migration is stuck. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Message-id: 1445951385-11924-1-git-send-email-dgilbert@redhat.com V2: Merge into one command with optional handlers arg, and only do backtrace in verbose mode (gdb) qemu handlers ---- {pfd = {fd = 6, events = 25, revents = 0}, io_read = 0x55869656ffd0 <event_notifier_dummy_cb>, io_write = 0x0, deleted = 0, opaque = 0x558698c4ce08, node = {le_next = 0x0, le_prev = 0x558698c4cdc0}} (gdb) qemu handlers iohandler_ctx ---- {pfd = {fd = 9, events = 25, revents = 0}, io_read = 0x558696581380 <fd_coroutine_enter>, io_write = 0x0, deleted = 0, opaque = 0x558698dc99d0, node = {le_next = 0x558698c4cca0, le_prev = 0x558698c4c1d0}} ---- {pfd = {fd = 4, events = 25, revents = 0}, io_read = 0x55869657b330 <sigfd_handler>, io_write = 0x0, deleted = 0, opaque = 0x4, node = {le_next = 0x558698c4c260, le_prev = 0x558699f72508}} ---- {pfd = {fd = 5, events = 25, revents = 0}, io_read = 0x55869656ffd0 <event_notifier_dummy_cb>, io_write = 0x0, deleted = 0, opaque = 0x558698c4c218, node = {le_next = 0x0, le_prev = 0x558698c4ccc8}} ---- (gdb) qemu handlers --verbose iohandler_ctx ---- {pfd = {fd = 9, events = 25, revents = 0}, io_read = 0x558696581380 <fd_coroutine_enter>, io_write = 0x0, deleted = 0, opaque = 0x558698dc99d0, node = {le_next = 0x558698c4cca0, le_prev = 0x558698c4c1d0}} #0 0x0000558696581820 in qemu_coroutine_switch (from_=from_@entry=0x558698cb3cf0, to_=to_@entry=0x7f421c37eac8, action=action@entry=COROUTINE_YIELD) at /home/dgilbert/git/qemu/coroutine-ucontext.c:177 #1 0x0000558696580c00 in qemu_coroutine_yield () at /home/dgilbert/git/qemu/qemu-coroutine.c:145 #2 0x00005586965814f5 in yield_until_fd_readable (fd=9) at /home/dgilbert/git/qemu/qemu-coroutine-io.c:90 #3 0x0000558696523937 in socket_get_buffer (opaque=0x55869a3dc620, buf=0x558698c505a0 "", pos=<optimized out>, size=32768) at /home/dgilbert/git/qemu/migration/qemu-file-unix.c:101 #4 0x0000558696521fac in qemu_fill_buffer (f=0x558698c50570) at /home/dgilbert/git/qemu/migration/qemu-file.c:227 #5 0x0000558696522989 in qemu_peek_byte (f=0x558698c50570, offset=0) at /home/dgilbert/git/qemu/migration/qemu-file.c:507 #6 0x0000558696522bf4 in qemu_get_be32 (f=0x558698c50570) at /home/dgilbert/git/qemu/migration/qemu-file.c:520 #7 0x0000558696522bf4 in qemu_get_be32 (f=f@entry=0x558698c50570) at /home/dgilbert/git/qemu/migration/qemu-file.c:604 #8 0x0000558696347e5c in qemu_loadvm_state (f=f@entry=0x558698c50570) at /home/dgilbert/git/qemu/migration/savevm.c:1821 #9 0x000055869651de8c in process_incoming_migration_co (opaque=0x558698c50570) at /home/dgilbert/git/qemu/migration/migration.c:336 #10 0x000055869658188a in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>) at /home/dgilbert/git/qemu/coroutine-ucontext.c:80 #11 0x00007f420f05df10 in __start_context () at /lib64/libc.so.6 #12 0x00007ffc40815f50 in () #13 0x0000000000000000 in () ---- Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2015-10-27 14:09:45 +01:00
#!/usr/bin/python
# GDB debugging support: aio/iohandler debug
#
# Copyright (c) 2015 Red Hat, Inc.
#
# Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
#
# This work is licensed under the terms of the GNU GPL, version 2 or
# later. See the COPYING file in the top-level directory.
#
import gdb
from qemugdb import coroutine
def isnull(ptr):
return ptr == gdb.Value(0).cast(ptr.type)
def dump_aiocontext(context, verbose):
'''Display a dump and backtrace for an aiocontext'''
cur = context['aio_handlers']['lh_first']
# Get pointers to functions we're going to process specially
sym_fd_coroutine_enter = gdb.parse_and_eval('fd_coroutine_enter')
while not isnull(cur):
entry = cur.dereference()
gdb.write('----\n%s\n' % entry)
if verbose and cur['io_read'] == sym_fd_coroutine_enter:
coptr = (cur['opaque'].cast(gdb.lookup_type('FDYieldUntilData').pointer()))['co']
coptr = coptr.cast(gdb.lookup_type('CoroutineUContext').pointer())
coroutine.bt_jmpbuf(coptr['env']['__jmpbuf'])
cur = cur['node']['le_next'];
gdb.write('----\n')
class HandlersCommand(gdb.Command):
'''Display aio handlers'''
def __init__(self):
gdb.Command.__init__(self, 'qemu handlers', gdb.COMMAND_DATA,
gdb.COMPLETE_NONE)
def invoke(self, arg, from_tty):
verbose = False
argv = gdb.string_to_argv(arg)
if len(argv) > 0 and argv[0] == '--verbose':
verbose = True
argv.pop(0)
if len(argv) > 1:
gdb.write('usage: qemu handlers [--verbose] [handler]\n')
return
if len(argv) == 1:
handlers_name = argv[0]
else:
handlers_name = 'qemu_aio_context'
dump_aiocontext(gdb.parse_and_eval(handlers_name), verbose)