• Frederic Weisbecker's avatar
    tracing: Dump either the oops's cpu source or all cpus buffers · cecbca96
    Frederic Weisbecker authored
    The ftrace_dump_on_oops kernel parameter, sysctl and sysrq let one
    dump every cpu buffers when an oops or panic happens.
    It's nice when you have few cpus but it may take ages if have many,
    plus you miss the real origin of the problem in all the cpu traces.
    Sometimes, all you need is to dump the cpu buffer that triggered the
    opps, most of the time it is our main interest.
    This patch modifies ftrace_dump_on_oops to handle this choice.
    The ftrace_dump_on_oops kernel parameter, when it comes alone, has
    the same behaviour than before. But ftrace_dump_on_oops=orig_cpu
    will only dump the buffer of the cpu that oops'ed.
    Similarly, sysctl kernel.ftrace_dump_on_oops=1 and
    echo 1 > /proc/sys/kernel/ftrace_dump_on_oops keep their previous
    behaviour. But setting 2 jumps into cpu origin dump mode.
    v2: Fix double setup
    v3: Fix spelling issues reported by Randy Dunlap
    v4: Also update __ftrace_dump in the selftests
    Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    Acked-by: default avatarDavid S. Miller <davem@davemloft.net>
    Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Li Zefan <lizf@cn.fujitsu.com>
    Cc: Lai Jiangshan <laijs@cn.fujitsu.com>