Re: [PATCH] fs: add FD_CLOFORK and O_CLOFORK
From: Eric Dumazet
Date: Sat May 07 2011 - 02:07:07 EST
Le samedi 07 mai 2011 Ã 12:49 +0800, Changli Gao a Ãcrit :
>
> for (i = open_files; i != 0; i--) {
> struct file *f = *old_fds++;
> if (f) {
> - get_file(f);
> + if (FD_ISSET(open_files - i, new_fdt->close_on_fork)) {
> + FD_CLR(open_files - i, new_fdt->open_fds);
> + f = NULL;
> + } else {
> + get_file(f);
> + }
> } else {
> /*
You should change the main loop to
for (i = 0; i < open_files; i++) {
struct file *f = *old_fds++;
if (f && FD_ISSET(i, new_fdt->close_on_fork))
f = NULL;
if (f)
get_file(f);
else
FD_CLR(i, new_fdt->open_fds)
rcu_assign_pointer(*new_fds++, f);
}
BTW the rcu_assign_pointer() is not necessary here, since we are the
only thread populating new_fds at this point.
spin_unlock(&oldf->file_lock); and
rcu_assign_pointer(newf->fdt, new_fdt);
make sure once new_fds is visible to other threads, all our memory
writes are committed.
sparse even warns us ;)
fs/file.c:371:3: warning: incorrect type in assignment (different address spaces)
fs/file.c:371:3: expected struct file *<noident>
fs/file.c:371:3: got struct file [noderef] <asn:4>*<noident>
I'll submit a patch in a separate thread
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