Gilles Chanteperdrix wrote: > On Nov 13, 2007 6:10 PM, Philippe Gerum <[EMAIL PROTECTED]> wrote: >> Gilles Chanteperdrix wrote: >>> On Nov 13, 2007 3:17 PM, Jan Kiszka <[EMAIL PROTECTED]> wrote: >>>> Gilles Chanteperdrix wrote: >>>>> Hi, >>>>> >>>>> I am chasing a slab corruption bug which happens on a Xenomai+RTnet >>>>> enabled box under heavy non real-time network load (which passes >>>>> through rtnet and rtmac_vnic to Linux which does NAT and resend it to >>>>> another rtmac_vnic). When reading some I-pipe tracer traces, I >>>>> remarked that I forgot to replace a local_irq_save/local_irq_restore >>>>> with local_irq_save_hw/local_irq_restore_hw in a real-time interrupt >>>>> handler. I fixed this bug, and the slab corruption seems to be gone. >>>> Hope you mean rtdm_lock_irqsave/irqrestore instead. Otherwise Xenomai's >>>> domain state would not be updated appropriately - which is at least >>>> unclean. >>> It is some low level secondary timer handling code, there is no rtdm >>> involved. The code protected by the interrupt masking routines is one >>> or two inline assembly instructions. >>> >>>> BTW, CONFIG_IPIPE_DEBUG_CONTEXT should have caught this bug as well. >>> I am using an old I-pipe pacth without CONFIG_IPIPE_DEBUG_CONTEXT. >>> I-pipe patch and Xenomai update is scheduled for when RT applications >>> and drivers porting will be finished. >>> >>> Besides the BUG_ON(!ipipe_root_domain_p) in ipipe_restore_root and >>> ipipe_unstall_root are unconditional. >>> >> What bothers me, is that even looking at the old 1.3 series here and on, >> the code should exhibit a call chain like >> local_irq_restore -> raw_local_irq_restore() -> __ipipe_restore_root -> >> __ipipe_unstall_root -> __ipipe_sync_stage, without touching the current >> domain pointer, which is ok, since well, it has to be right in the first >> place. If we were running over a real-time handler, then I assume the >> Xenomai domain was active. So BUG_ON() should have triggered if present >> in __ipipe_unstall_root. > > I am using an I-pipe arm 1.5-04 (now that I have done cat > /proc/ipipe/version, I really feel ashamed). And it has no BUG_ON in > __ipipe_unstall_root or __ipipe_restore_root. I promise, one day, I > will switch to Xenomai 2.4. > >> Additionally, calling __ipipe_sync_pipeline() would sync the current >> stage, i.e. Xenomai, and run the real-time ISRs, not the Linux handlers. >> >> Mm, ok, in short: I have no clue. > > The system runs stably, so I have to assume that calling > local_irq_restore in a real-time interrupt handler can cause slab > corruption. Strange.
What about instrumenting the involved I-pipe code path with ipipe_trace_specials and then restoring the buggy code. You may even ipipe_trace_freeze on that spot so that you can watch in pre/post trace what happens. May help to understand if this was the only issue, or if we may need some further measures for future versions. Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux _______________________________________________ Xenomai-core mailing list Xenomaifirstname.lastname@example.org https://mail.gna.org/listinfo/xenomai-core