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Date: Thu, 5 Jan 2012 15:10:25 -0500 From: Seiji Aguchi <seiji.aguchi@....com> To: "Luck, Tony" <tony.luck@...el.com>, Don Zickus <dzickus@...hat.com> CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Matthew Garrett <mjg@...hat.com>, Vivek Goyal <vgoyal@...hat.com>, "Chen, Gong" <gong.chen@...el.com>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "Brown, Len" <len.brown@...el.com>, "'ying.huang@...el.com'" <'ying.huang@...el.com'>, "'ak@...ux.intel.com'" <'ak@...ux.intel.com'>, "'hughd@...omium.org'" <'hughd@...omium.org'>, "'mingo@...e.hu'" <'mingo@...e.hu'>, "jmorris@...ei.org" <jmorris@...ei.org>, "a.p.zijlstra@...llo.nl" <a.p.zijlstra@...llo.nl>, "namhyung@...il.com" <namhyung@...il.com>, "dle-develop@...ts.sourceforge.net" <dle-develop@...ts.sourceforge.net>, Satoru Moriya <satoru.moriya@....com> Subject: RE: [RFC][PATCH v4 -next 1/4] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop() >Aren't you worried about the comment about smp_send_stop() not >being hardened to work in a panic situation? > /* > * Note smp_send_stop is the usual smp shutdown function, which > * unfortunately means it may not be hardened to work in a panic This comment is wrong because Don improved smp_send_stop() by switching REBOOT_VECTOR to NMI. And his patch has already merged to linux-next tree. http://git.kernel.org/?p=linux/kernel/git/next/linux-next.git;a=commitdiff;h=3603a2512f9e69dc87914ba922eb4a0812b21cd6 So, current smp_send_stop() is hardened to work in a panic situation. I will remove this wrong comment. Seiji >-----Original Message----- >From: Luck, Tony [mailto:tony.luck@...el.com] >Sent: Thursday, January 05, 2012 2:07 PM >To: Seiji Aguchi; Don Zickus >Cc: linux-kernel@...r.kernel.org; Matthew Garrett; Vivek Goyal; Chen, Gong; akpm@...ux-foundation.org; Brown, Len; >'ying.huang@...el.com'; 'ak@...ux.intel.com'; 'hughd@...omium.org'; 'mingo@...e.hu'; jmorris@...ei.org; >a.p.zijlstra@...llo.nl; namhyung@...il.com; dle-develop@...ts.sourceforge.net; Satoru Moriya >Subject: RE: [RFC][PATCH v4 -next 1/4] Move kmsg_dump(KMSG_DUMP_PANIC) below smp_send_stop() > >- kmsg_dump(KMSG_DUMP_PANIC); >- > /* > * Note smp_send_stop is the usual smp shutdown function, which > * unfortunately means it may not be hardened to work in a panic >@@ -117,6 +115,8 @@ void panic(const char *fmt, ...) > */ > smp_send_stop(); > >+ kmsg_dump(KMSG_DUMP_PANIC); >+ > >Aren't you worried about the comment about smp_send_stop() not >being hardened to work in a panic situation? > >If it does work - we are clearly much better off moving the >kmsg_dump() call down like this. It makes life much simpler >and cleaner to work with just one running cpu. > >But if something goes wrong - we might not see the dump at all! > >How do we compare these cases and decide that it is better to >trust that smp_send_stop() will return? > >-Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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