(2013/12/11 0:57), Oleg Nesterov wrote: > On 12/10, Masami Hiramatsu wrote: >> >> (2013/12/09 15:20), Namhyung Kim wrote: >>> From: Oleg Nesterov <o...@redhat.com> >>> >>> uprobe_trace_print() and uprobe_perf_print() need to pass the additional >>> info to call_fetch() methods, currently there is no simple way to do this. >>> >>> current->utask looks like a natural place to hold this info, but we need >>> to allocate it before handler_chain(). >>> >>> This is a bit unfortunate, perhaps we will find a better solution later, >>> but this is simnple and should work right now. >> >> Hmm, when this will happen? > > Perhaps never. Perhaps it will stay forever and we remove get_utask() from > pre_ssout() (it is not needed after this patch).
Ah, OK, get_utask() is almost same as kzalloc(). > However I still think we can cleanup this. And to remind, we need to clean > the usage of utask->vaddr in trace_uprobe.c anyway. We can either try to > find another place to pass the info, or we can create a helper(s) for the > tracing handlers to access (and populate if NULL) utask->handler_data. > Note that this (probably) also makes sense because we can unexport > "struct uprobe_task" (but this needs a couple of off-topic cleanups). > > We will see. Lets do the minimal change which can work right now, Namhyung > has enough more serious problems ;) > >> and isn't it better to increment >> miss-hit counter of the uprobe? > > What do you mean? This is not miss-hit and ->utask == NULL is quite normal. But it could skip the handler_chain silently. It could confuse users why their probe doesn't hit as expected. > For example, on ppc it can be always NULL because ppc likely emulates the > probed insn. Hmm, in that case, should uprobes handlers never be called on ppc with this change? > Or did you mean that if get_utask() fails we should report this somehow? I meant that if the uprobes hits some error and not work as expected, it should be reported somehow to users, and miss-hit counter will be a possible option. Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
