Re: [ptrace] please review follow fork/exec changes


On 2012/1/26 7:48, Dmitry Mikulin wrote:
> <snip>

> The debugger needs to intercept fork() in both parent and child so it 
> can detach from the old process and attach to the new one. Maybe it'll 
> make more sense in the context of gdb changes. Should I send them too? 
> Don't think Marcel included that patch...
>
>>
>> Does the orphan list change intended to not lost the child after fork ?
>> But the child shall be traced, so debugger would get the SIGTRAP on
>> the attach on fork returning to usermode. I remember that I explicitely
>> tested this when adding followfork changes.
>
> Yes, the debugger gets SIGTRAPs. The problem arises when the real 
> parent of the forked process has the code to collect termination 
> status. Since attaching to a process changes the parent/child 
> relationships, we need to keep track of the children lost due to 
> re-parenting so we can properly attribute their exit status to the 
> "real" parent.
>
I recall that someone brought a topic in the list said that this should 
be fixed, debugging a process should not change
parent-child relation, instead a new link list data structure should be 
added to struct proc  to trace debugged process,
this will make code clean with a small memory overhead.

Regards,
David Xu


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