Re: s390 user_enable_single_step() (Was: odd utrace testing results on s390x)

2010-01-07 Thread Oleg Nesterov
Martin, sorry for delay, On 01/07, Martin Schwidefsky wrote: On Wed, 6 Jan 2010 13:13:29 -0800 (PST) Roland McGrath rol...@redhat.com wrote: However, with or without CONFIG_UTRACE, 6580807da14c423f0d0a708108e6df6ebc8bc83d is needed on s390 too, otherwise the child gets unnecessary

Re: s390 user_enable_single_step() (Was: odd utrace testing results on s390x)

2010-01-07 Thread Oleg Nesterov
On 01/07, Martin Schwidefsky wrote: On Wed, 6 Jan 2010 13:08:12 -0800 (PST) Roland McGrath rol...@redhat.com wrote: That's what tracehook_signal_handler is for. You're both doing it yourself in the arch code (by setting TIF_SINGLE_STEP), and then telling the generic code to do it (by

Re: s390 user_enable_single_step() (Was: odd utrace testing results on s390x)

2010-01-07 Thread Roland McGrath
Right. That means we should leave the status quo of not clearing TIF_SINGLE_STEP in user_disable_single_step. Ok, although it seems a bit strange not to do it. Perhaps I should add a comment about it. It doesn't seem strange to me, but then I've just been through all this. user_*_step is

Re: s390 user_enable_single_step() (Was: odd utrace testing results on s390x)

2010-01-07 Thread Roland McGrath
Hmm, command for tracehook_signal_handler say this for stepping: @stepping: nonzero if debugger single-step or block-step in use Are you saying you would like me to clarify that wording somehow? It's meant to be implicit that the arch code is not doing any special fakery about

Re: s390 user_enable_single_step() (Was: odd utrace testing results on s390x)

2010-01-07 Thread Roland McGrath
Clear the TIF_SINGLE_STEP bit in copy_thread. If the new process is not auto-attached by the tracer it is wrong to delivere SIGTRAP to the new process. The change is right, but this log entry is confusing. auto-attached has nothing to do with it, nor does anything about tracing the new

Re: s390 user_enable_single_step() (Was: odd utrace testing results on s390x)

2010-01-07 Thread Roland McGrath
I am confused as well. Yes, I thought about regs-psw.mask change too, but I don't understand why it helps.. [...] But. Acoording to the testing I did (unless I did something wrong again) this patch doesn't make any difference in this particular case. 6580807da14c423f0d0a708108e6df6ebc8bc83d