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    SubjectRe: [PATCHv10 2.6.35-rc6-tip 8/14] trace: Extract out common code for kprobes/uprobes traceevents.
    Srikar Dronamraju wrote:
    >>> ---
    >> [...]
    >>> +/* Recursive argument parser */
    >>> +static int parse_probe_arg(char *arg, const struct fetch_type *t,
    >>> + struct fetch_param *f, int is_return, bool is_kprobe)
    >> If you use "bool" for "is_kprobe", change "is_return" type too.
    > Okay.
    >> And, maybe you missed that the fetch function supports "string" type now,
    >> which needs a bit different manner for storing fetched value. You can find
    >> store_trace_args() function in trace_kprobe.c.
    > Yes, I have seen your changes for supporting string type. Though all
    > the fetch functions are in common code, uprobe based probes for now
    > supports register fetching only. We have to add support for other
    > types gradually. Please let me know if you see a reason to change the
    > way we fetch even when we only support register type access.

    Ah, OK. So uprobe-tracer restricts specifying string type on register :)

    >> BTW, current fetch functions doesn't support fetching "paged-out" user-variables
    >> because kprobe can't sleep inside its handler.
    >> However, user-space memory can be paged out, and I assume that uprobes allows
    >> its handler to I/O (and yield). If so, it can wait for accessing paged-out
    >> variable, can't it?
    > Yes, the uprobes handler might sleep and hence we would have to
    > handle accessing the paged-out user variables. When perf-uprobes
    > starts supporting dwarf based probing, we should look into these
    > issues. Currently its a todo.


    Thank you,

    Masami HIRAMATSU
    2nd Research Dept.
    Hitachi, Ltd., Systems Development Laboratory

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