(2014/11/26 18:18), Jiri Kosina wrote: > On Wed, 26 Nov 2014, Masami Hiramatsu wrote: > >>> Note to Steve: >>> Masami's IPMODIFY patch is heading for -next via your tree. Once it arrives, >>> I'll rebase and make the change to set IPMODIFY. Do not pull this for -next >>> yet. This version (v4) is for review and gathering acks. >> >> BTW, as we discussed IPMODIFY is an exclusive flag. So if we allocate >> ftrace_ops for each function in each patch, it could be conflict each >> other. > > Yup, this corresponds to what Petr brought up yesterday. There are cases > where all solutions (kpatch, kgraft, klp) would allocate multiple > ftrace_ops for a single function entry (think of patching one function > multiple times in a row). > > So it's not as easy as just setting the flag. > >> Maybe we need to have another ops hashtable to find such conflict and >> new handler to handle it. > > If I understand your proposal correctly, that would sound like a hackish > workaround, trying to basically trick the IPMODIFY flag semantics you just > implemented :) > > What I'd propose instead is to make sure that we always have > just a ftrace_ops per function entry, and only update the pointers there > as necessary. Fortunately we can do the switch atomically, by making use > of ->private. Would you mean per existing function entry, not per klp-func entry? If so, it sounds good to me too :) Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@xxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
