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    SubjectFwd: [PATCH] kdb: Avoid using dbg_io_ops until it is initialized

    This patch has apparently fallen through the cracks. Can you please apply?
    This fixes a kernel panic for a use case where I'm setting a breakpoint
    from kdb_cmds on kernel startup. In this case, without this patch
    dbg_io_ops is used before it is initialized.

    -- Tim

    -------- Original Message --------
    Subject: [PATCH] kdb: Avoid using dbg_io_ops until it is initialized
    Date: Wed, 21 Sep 2011 13:19:12 -0700
    From: Tim Bird <>
    To: Jason Wessel <>
    CC: <>, linux kernel <>

    This fixes a bug with setting a breakpoint during kdb initialization
    (from kdb_cmds). Any call to kdb_printf() before the initialization
    of the kgdboc serial console driver (which happens much later in
    bootup than kdb_init), results in kernel panic due to the use of
    dbg_io_ops before it is initialized.

    Signed-off-by: Tim Bird <>
    kernel/debug/kdb/kdb_io.c | 2 +-
    1 files changed, 1 insertions(+), 1 deletions(-)

    diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
    index c9b7f4f..3bc995f 100644
    --- a/kernel/debug/kdb/kdb_io.c
    +++ b/kernel/debug/kdb/kdb_io.c
    @@ -675,7 +675,7 @@ kdb_printit:
    if (!dbg_kdb_mode && kgdb_connected) {
    gdbstub_msg_write(kdb_buffer, retlen);
    } else {
    - if (!dbg_io_ops->is_console) {
    + if (dbg_io_ops && !dbg_io_ops->is_console) {
    len = strlen(kdb_buffer);
    cp = kdb_buffer;
    while (len--) {

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