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Date: Tue, 18 Nov 2014 15:25:34 +0900 From: Namhyung Kim <namhyung@...nel.org> To: kan.liang@...el.com Cc: acme@...nel.org, jolsa@...hat.com, a.p.zijlstra@...llo.nl, eranian@...gle.com, linux-kernel@...r.kernel.org, mingo@...hat.com, paulus@...ba.org, ak@...ux.intel.com Subject: Re: [PATCH V3 3/3] perf tools: Construct LBR call chain On Fri, 14 Nov 2014 08:44:12 -0500, kan liang wrote: > + /* LBR only affects the user callchain */ > + if (i != chain_nr) { > + struct branch_stack *lbr_stack = sample->branch_stack; > + int lbr_nr = lbr_stack->nr; > + /* > + * LBR callstack can only get user call chain. > + * The mix_chain_nr is kernel call chain > + * number plus LBR user call chain number. > + * i is kernel call chain number, > + * 1 is PERF_CONTEXT_USER, > + * lbr_nr + 1 is the user call chain number. > + * For details, please refer to the comments > + * in callchain__printf > + */ > + int mix_chain_nr = i + 1 + lbr_nr + 1; > + > + if (mix_chain_nr > PERF_MAX_STACK_DEPTH) { > + pr_warning("corrupted callchain. skipping...\n"); > + return 0; > + } I'm not sure whether this is really a corrupted callchain. If a single chain is greater than the max it should be corrupted, but we're now summing up with other values.. What about checking callchain_nr and lbr_nr separately or mix_nr with 2*max? Thanks, Namhyung -- 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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