On Fri, Mar 27, 2020 at 11:59:37AM +0100, Philippe Mathieu-Daudé wrote: > On 3/27/20 6:14 AM, Emilio G. Cota wrote: > > (Apologies if I missed some Cc's; I was not Cc'ed in patch 0 > > so I'm blindly crafting a reply.) > > > > On Thu, Mar 26, 2020 at 15:30:43 -0400, Robert Foley wrote: > > > This is a continuation of the series created by Emilio Cota. > > > We are picking up this patch set with the goal to apply > > > any fixes or updates needed to get this accepted. > > > > Thanks for picking this up! > > > > > Listed below are the changes for this version of the patch, > > > aside from the merge related changes. > > > > > > Changes for V8: > > > - Fixed issue where in rr mode we could destroy the BQL twice. > > > > I remember doing little to no testing in record-replay mode, so > > there should be more bugs hiding in there :-) > > > > > - Found/fixed bug that had been hit in testing previously during > > > the last consideration of this patch. > > > We reproduced the issue hit in the qtest: bios-tables-test. > > > The issue was introduced by dropping the BQL, and found us > > > (very rarely) missing the condition variable wakeup in > > > qemu_tcg_rr_cpu_thread_fn(). > > > > Aah, this one: > > https://patchwork.kernel.org/patch/10838149/#22516931 > > How did you identify the problem? Was it code inspection or using a tool > > like rr? I remember this being hard to reproduce reliably. > > > > On a related note, I've done some work to get QEMU-system to work > > under thread sanitizer, since tsan now supports our longjmp-based > > coroutines (hurrah!). My idea was to integrate tsan in QEMU (i.e. > > bring tsan warnings to 0) before (re)trying to merge the > > per-CPU lock patchset; this would minimize the potential for > > regressions, which from my personal viewpoint seems like a reasonable > > thing to do especially now that I have little time to work on QEMU. > > > > If there's interest in doing the tsan work first, then I'd be > > happy to send to the list as soon as this weekend the changes that > > I have so far [1]. > > I'm pretty sure Marc-André is interested (and also Stefan maybe), so Cc'ing > them.
Yes, please! tsan would be another good tool to have. Stefan
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