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    Subject[RESEND PATCH 3.18-rc3] kdb: Avoid printing KERN_ levels to consoles
    Date
    Currently when kdb traps printk messages then the raw log level prefix
    (consisting of '\001' followed by a numeral) does not get stripped off
    before the message is issued to the various I/O handlers supported by
    kdb. This causes annoying visual noise as well as causing problems
    grepping for ^. It is also a change of behaviour compared to normal usage
    of printk() usage. For example <SysRq>-h ends up with different to that of
    kdb's "sr h".

    This patch addresses the problem by stripping log levels from messages
    before they are issued to the I/O handlers.

    printk(), which is used as an I/O handler for logging purposes, is
    handled as a special case; if the caller provided a log level then this
    will be preserved.

    Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
    Cc: Jason Wessel <jason.wessel@windriver.com>
    ---

    Notes:
    This patch is tested both on arm (kgdboc=ttyAMA0) and x86_64
    (kgdboc=kdb,ttyS0).


    kernel/debug/kdb/kdb_io.c | 20 +++++++++++++-------
    1 file changed, 13 insertions(+), 7 deletions(-)

    diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
    index 7c70812..381f297 100644
    --- a/kernel/debug/kdb/kdb_io.c
    +++ b/kernel/debug/kdb/kdb_io.c
    @@ -691,19 +691,22 @@ kdb_printit:
    * Write to all consoles.
    */
    retlen = strlen(kdb_buffer);
    + cp = kdb_buffer;
    + if (cp[0] == KERN_SOH_ASCII && cp[1] != '\0')
    + cp += 2;
    if (!dbg_kdb_mode && kgdb_connected) {
    - gdbstub_msg_write(kdb_buffer, retlen);
    + gdbstub_msg_write(cp, retlen - (cp - kdb_buffer));
    } else {
    if (dbg_io_ops && !dbg_io_ops->is_console) {
    - len = retlen;
    - cp = kdb_buffer;
    + len = retlen - (cp - kdb_buffer);
    + cp2 = cp;
    while (len--) {
    - dbg_io_ops->write_char(*cp);
    - cp++;
    + dbg_io_ops->write_char(*cp2);
    + cp2++;
    }
    }
    while (c) {
    - c->write(c, kdb_buffer, retlen);
    + c->write(c, cp, retlen - (cp - kdb_buffer));
    touch_nmi_watchdog();
    c = c->next;
    }
    @@ -711,7 +714,10 @@ kdb_printit:
    if (logging) {
    saved_loglevel = console_loglevel;
    console_loglevel = CONSOLE_LOGLEVEL_SILENT;
    - printk(KERN_INFO "%s", kdb_buffer);
    + if (cp == kdb_buffer)
    + printk(KERN_INFO "%s", kdb_buffer);
    + else
    + printk("%s", kdb_buffer);
    }

    if (KDB_STATE(PAGER)) {
    --
    1.9.3


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