Messages in this thread |  | | Date | Wed, 11 Dec 2013 19:11:55 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 16/17] uprobes: Allocate ->utask before handler_chain() for tracing handlers |
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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.
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.
Oleg.
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