From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4739DA74.7040409@domain.hid> Date: Tue, 13 Nov 2007 18:10:12 +0100 From: Philippe Gerum MIME-Version: 1.0 References: <2ff1a98a0711130556j58141e80yc0bca6b574fad7e9@domain.hid> <4739B1DC.4030705@domain.hid> <2ff1a98a0711130634x552683c4ib1c420a859a4d665@domain.hid> In-Reply-To: <2ff1a98a0711130634x552683c4ib1c420a859a4d665@domain.hid> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: Philippe Gerum Subject: Re: [Xenomai-core] local_irq_save/local_irq_restore in real-time interrupt handler and slab corruption. Reply-To: rpm@xenomai.org List-Id: "Xenomai life and development \(bug reports, patches, discussions\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gilles Chanteperdrix Cc: xenomai-core Gilles Chanteperdrix wrote: > On Nov 13, 2007 3:17 PM, Jan Kiszka 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. 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. -- Philippe.