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SubjectRe: Re: [PATCH ftrace/core v3 3/3] kprobes: Set IPMODIFY flag only if the probe can change regs->ip
(2014/07/18 14:32), Namhyung Kim wrote:
> Hi Masami,
>
> On Tue, 15 Jul 2014 06:00:35 +0000, Masami Hiramatsu wrote:
>> +static int __ftrace_add_filter_ip(struct ftrace_ops *ops, unsigned long ip,
>> + int *ref)
>> +{
>> + int ret;
>> +
>> + /* Try to set given ip to filter */
>> + ret = ftrace_set_filter_ip(ops, ip, 0, 0);
>> + if (ret < 0)
>> + return ret;
>> +
>> + (*ref)++;
>> + if (*ref == 1) {
>> + ret = register_ftrace_function(ops);
>> + if (ret < 0) {
>> + /* Rollback refcounter and filter */
>> + (*ref)--;
>> + ftrace_set_filter_ip(ops, ip, 1, 0);
>> + }
>> + }
>> +
>> + return ret;
>> +}
>
> This function also can be changed in a similar way:
>
> if (*ref == 0) {
> ret = register_ftrace_function(ops);
> if (ret < 0) {
> /* Rollback filter if failed */
> ftrace_set_filter_ip(ops, ip, 1, 0);
> return ret;
> }
> }
>
> (*ref)++;
>
> return 0;

Indeed :)

Thanks!


--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com




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