From: Steven Rostedt Revert the commit that removed the disabling of interrupts around the initial modifying of mcount callers to nops, and update the comment. The original comment was outdated and stated that the interrupts were being disabled to prevent kstop machine, which was required with the old ftrace daemon, but was no longer the case. What the comment failed to mention was that interrupts needed to be disabled to keep interrupts from preempting the modifying of the code and then executing the code that was partially modified. Revert the commit and update the comment. Reported-by: Richard W.M. Jones Tested-by: Richard W.M. Jones Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 204b3eb..908038f 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3330,6 +3330,7 @@ static int ftrace_process_locs(struct module *mod, { unsigned long *p; unsigned long addr; + unsigned long flags; mutex_lock(&ftrace_lock); p = start; @@ -3346,7 +3347,13 @@ static int ftrace_process_locs(struct module *mod, ftrace_record_ip(addr); } + /* + * Disable interrupts to prevent interrupts from executing + * code that is being modified. + */ + local_irq_save(flags); ftrace_update_code(mod); + local_irq_restore(flags); mutex_unlock(&ftrace_lock); return 0; -- 1.7.4.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/