Hi Srikar, On 07/04/2018 02:46 PM, Srikar Dronamraju wrote: >> >> I'm not sure if I get your concerns but let me try to explain what happens >> in such cases. please let me know if I misunderstood your point. >> >> 1. Install a probe using perf. >> # ./perf probe sdt_tick:loop2 >> >> >> >> Does this explain your concerns? >> > > > No, this was not my concern. > My concern is with two users on the same USDT. > 1. First user enables the probe point but doesn't increment the ref_cnt. > via uprobe_register > > 2. Second user tries to enable the probe point and also increments the > ref_cnt via uprobe_register_refctr. Ok got it. uprobe_register_refctr() will return with error because we don't allow one uprobe(inode+offset) with multiple reference counter. i.e. If inode+offset matches for two uprobes, ref_ctr_offset must match as well. Patch 8/10 takes care of this. > > 3. If the second user now removes the probe point via uprobe_unregister. > > 4. What is the state of the ref_cnt? > > -- > Thanks and Regards > Srikar >
