Replace the fd_sets in struct fdtable with an array of unsigned longs

Replace the fd_sets in struct fdtable with an array of unsigned longs and then
use the standard non-atomic bit operations rather than the FD_* macros.

This:

 (1) Removes the abuses of struct fd_set:

     (a) Since we don't want to allocate a full fd_set the vast majority of the
     	 time, we actually, in effect, just allocate a just-big-enough array of
     	 unsigned longs and cast it to an fd_set type - so why bother with the
     	 fd_set at all?

     (b) Some places outside of the core fdtable handling code (such as
     	 SELinux) want to look inside the array of unsigned longs hidden inside
     	 the fd_set struct for more efficient iteration over the entire set.

 (2) Eliminates the use of FD_*() macros in the kernel completely.

 (3) Permits the __FD_*() macros to be deleted entirely where not exposed to
     userspace.

Signed-off-by: David Howells <dhowells@redhat.com>
Link: http://lkml.kernel.org/r/20120216174954.23314.48147.stgit@warthog.procyon.org.uk
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/select.c b/fs/select.c
index d33418fdc85..2e7fbe8a092 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -348,7 +348,7 @@ static int max_select_fd(unsigned long n, fd_set_bits *fds)
 	set = ~(~0UL << (n & (__NFDBITS-1)));
 	n /= __NFDBITS;
 	fdt = files_fdtable(current->files);
-	open_fds = fdt->open_fds->fds_bits+n;
+	open_fds = fdt->open_fds + n;
 	max = 0;
 	if (set) {
 		set &= BITS(fds, n);