Re: [PATCH v5 06/10] Uprobes: Support SDT markers having reference count (semaphore)

[Ravi Bangoria]

Hi Song,

On 07/14/2018 05:20 AM, Song Liu wrote:
> 
> Hmm... what happens when we have multiple uprobes sharing the same
> reference counter? It feels equally complicate to me. Or did I miss any
> cases here?


As far as I can think of, it should be handled by default. No special
treatment needed for this.

...

> 
> This patch tries to resolve this imbalance by passing extra flag
> "restore_insn" to probe_event_disable().
> 
> Signed-off-by: Song Liu <songliubraving@xxxxxx>


Ah cool. Seems this will make them balanced. But is it fine to change
uprobe_unregister()? It's already an ABI. No other way around?

Also, one more source of imbalance is this condition:

          if (is_register)
                  flags |= VM_WRITE;

in valid_vma(). You need to take care of that as well.

Thanks,
Ravi