On 15.02.2018 10:14, Richard Weinberger wrote:
On Wed, Feb 14, 2018 at 10:13 PM, Enrico Weigelt <l...@metux.net> wrote:
Hi folks,
in fork.c, a spinlock is held for fs_struct refcounting, while other
places - eg. switch_task_namespaces uses atomic_dec_and_test() on
the nsproxy.
What's the exact difference here ? Could the atomic counting also used
for fs_struct ?
Well, the spinlock protects more than just the counter. So atomic won't do it.
Okay. Is that needed in that case ?
See unshare() syscall:
if (new_fs) {
fs = current->fs;
spin_lock(&fs->lock);
current->fs = new_fs;
if (--fs->users)
new_fs = NULL;
else
new_fs = fs;
spin_unlock(&fs->lock);
}
Seems to me, that we're just refcounting here, and once it went dont to
zero, nobody else can access it anymore.
--mtx
--
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
i...@metux.net -- +49-151-27565287
