Date: Fri, 20 Sep 2013 09:44:52 +0400 From: Gleb Smirnoff <glebius@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: ipmi patch for review Message-ID: <20130920054452.GB4574@glebius.int.ru> In-Reply-To: <201309191504.46986.jhb@freebsd.org> References: <20130917102110.GK4574@glebius.int.ru> <201309191504.46986.jhb@freebsd.org>
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John, On Thu, Sep 19, 2013 at 03:04:46PM -0400, John Baldwin wrote: J> > When system is writing a kernel core dump, it issues watchdog J> > pat wdog_kern_pat(WD_LASTVAL). If ipmi is in action, it registers J> > ipmi_wd_event() as event for watchdog. Thus ipmi_wd_event() is J> > called in dumping context. J> > J> > The problem is that ipmi_wd_event() calls into ipmi_set_watchdog(), J> > that calls into ipmi_alloc_request(), which uses M_WAITOK and J> > thus sleeps. This is a smaller problem, since can be converted to J> > M_NOWAIT. But ipmi_set_watchdog() then calls into J> > ipmi_submit_driver_request(), which calls msleep() any time. J> > J> > The attached patch allows me to successfully write cores in J> > presence of IPMI. J> J> Of course, the watchdog might go off during your dump. :) Yes, I understand that :( But, imho patch improves situation, although is ugly. J> The real fix is more complicated, which is that we should not use J> a worker thread for at least SMIC and KCS. -- Totus tuus, Glebius.
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