Messages in this thread |  | | Date | Thu, 12 Dec 2013 14:55:57 +0900 | From | Masami Hiramatsu <> | Subject | Re: Re: [PATCH 16/17] uprobes: Allocate ->utask before handler_chain() for tracing handlers |
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(2013/12/12 3:11), Oleg Nesterov wrote: > On 12/11, Masami Hiramatsu wrote: >> >> (2013/12/11 0:57), Oleg Nesterov wrote: >>> On 12/10, Masami Hiramatsu wrote: >>>> >>>> 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. > > No, we will restart the same (probed) instruction, handle_swbp() > will be called again, get_utask() will be called again.
Hmm, in that case, how would you avoid infinite recursive loop?? Would you repeat it until get_utask() != NULL?
> Not to mention that (in practice) if GFP_KERNEL fails the task is > already killed. > >>> 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? > > Why? With this change ppc will have ->utask != NULL even if it doesn't > need it at all.
Ah, I see. This changes that.
Thank you,
-- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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