Messages in this thread Patch in this message | | | From | Josef Bacik <> | Subject | [PATCH] trace: reenable preemption if we modify the ip | Date | Fri, 15 Dec 2017 21:42:57 -0500 |
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From: Josef Bacik <jbacik@fb.com>
Things got moved around between the original bpf_override_return patches and the final version, and now the ftrace kprobe dispatcher assumes if you modified the ip that you also enabled preemption. Make a comment of this and enable preemption, this fixes the lockdep splat that happened when using this feature.
Signed-off-by: Josef Bacik <jbacik@fb.com> --- kernel/trace/trace_kprobe.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 5db849809a56..91f4b57dab82 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1322,8 +1322,15 @@ static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs) if (tk->tp.flags & TP_FLAG_TRACE) kprobe_trace_func(tk, regs); #ifdef CONFIG_PERF_EVENTS - if (tk->tp.flags & TP_FLAG_PROFILE) + if (tk->tp.flags & TP_FLAG_PROFILE) { ret = kprobe_perf_func(tk, regs); + /* + * The ftrace kprobe handler leaves it up to us to re-enable + * preemption here before returning if we've modified the ip. + */ + if (ret) + preempt_enable_no_resched(); + } #endif return ret; } -- 2.7.5
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