• Dr. David Alan Gilbert's avatar
    gdb command: qemu handlers · c900ef86
    Dr. David Alan Gilbert authored
    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: 's avatarDr. 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: 's avatarStefan Hajnoczi <stefanha@redhat.com>
    c900ef86