libprocessgroup: Remove unnecessary permissions change in uid/pid hierarchy

When a new process is launched it ensures that all files under its uid/
and uid/pid hierarchy are accessible by the user/group of that process.
If the directory already exists that means the access permissions have
been already set before, therefore we do not need to reset them again.
This also avoids a race between two processes in the same uid with one
process being launched and walking the uid/ directory while the other
process is being killed and changing the content of that directory. In
such a race the process walking uid/ might find the uid/pid directory of
the process being killed but by the time it tries to set its permissions
the directory might be removed because the process got killed. The
change eliminates the possibility of this race.

Bug: 192421915
Bug: 192512069
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I182298c36f6b0b4580ab59e440bd3aea16f5fbfe

0 files changed, 0 insertions, 0 deletions