From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josef Bacik Subject: [PATCH] trace: reenable preemption if we modify the ip Date: Fri, 15 Dec 2017 21:42:57 -0500 Message-ID: <1513392177-10298-1-git-send-email-josef@toxicpanda.com> Cc: Josef Bacik To: netdev@vger.kernel.org, mhiramat@kernel.org, ast@kernel.org, daniel@iogearbox.net, darrick.wong@oracle.com, linux-kernel@vger.kernel.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Josef Bacik 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 --- 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