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authorDr. David Alan Gilbert <dgilbert@redhat.com>2015-10-27 13:09:45 +0000
committerStefan Hajnoczi <stefanha@redhat.com>2015-10-29 17:59:27 +0000
commitc900ef86c5e30e1adec0f79350edc3f30ebee285 (patch)
tree3960077dadb7a41f8683afd5725783e6c8b1a86d /scripts/qemugdb
parented65fd1a2750d24290354cc7ea49caec7c13e30b (diff)
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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>
Diffstat (limited to 'scripts/qemugdb')
-rw-r--r--scripts/qemugdb/aio.py58
1 files changed, 58 insertions, 0 deletions
diff --git a/scripts/qemugdb/aio.py b/scripts/qemugdb/aio.py
new file mode 100644
index 0000000..2ba00c4
--- /dev/null
+++ b/scripts/qemugdb/aio.py
@@ -0,0 +1,58 @@
+#!/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)