Date: Sun, 16 Dec 2012 10:49:49 -0800 From: Attilio Rao <attilio@freebsd.org> To: Andriy Gapon <avg@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r243515 - head/sys/kern Message-ID: <CAJ-FndAv0N12uCDGy7HPfigeDjaJV-mFPiHtzonBihfFENkuEA@mail.gmail.com> In-Reply-To: <50CD9B85.1040404@FreeBSD.org> References: <201211251422.qAPEM8BV074656@svn.freebsd.org> <CAJ-FndCGe=DtqKxRe0YXV0GJrf4CV6MX9B1MR-Uyy6A3hpongA@mail.gmail.com> <50C9B525.2060503@FreeBSD.org> <CAJ-FndAsjZSK9XGFhHvdcD5135Xo4acybPDtZ0J9jXeAMpH5%2BQ@mail.gmail.com> <50CD9B85.1040404@FreeBSD.org>
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On Sun, Dec 16, 2012 at 1:59 AM, Andriy Gapon <avg@freebsd.org> wrote: > on 13/12/2012 22:17 Attilio Rao said the following: >> Right, but as I said, for the time being we can at least have a >> correct panic() semantic and take the right time to fix the >> generic_stop_cpus() and then absorb also the panic() fix into it. >> Right now the mechanism is still broken in panic and it can be fixed >> with a very easy fix, so we should just do it. >> This will also help vendors like Sandvine which may have hit just this bug too. > > > Perhaps I got confused... > Could you please re-explain to me your suggestion to fix panic(9)? > Because I thought that it would require exactly the same steps as fixing > generic_stop_cpus(). Sorry about this. - about generic_stop_cpus() we need to implement all the things we discussed which are quite a few and for some things, like avoiding races between stop map, wakeup and set of cupid I admit I'm still not sure how easilly can be done without locking - about panic(), the check is much more easy, just see my first response to Ryan, because we don't have the wakeup/restart race as generic_stop_cpu() does. I propose to at least fix panic for the time being. Once generic_stop_cpus() is fully functional we can get rid of panic() chunk altogether. Attilio -- Peace can only be achieved by understanding - A. Einstein
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