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

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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>
This commit is contained in:
David Howells
2012-02-16 17:49:54 +00:00
committed by H. Peter Anvin
parent 1dce27c5aa
commit 1fd36adcd9
6 changed files with 37 additions and 47 deletions
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4
fs/exec.c
View File

@@ -1026,10 +1026,10 @@ static void flush_old_files(struct files_struct * files)
fdt = files_fdtable(files);
if (i >= fdt->max_fds)
break;
set = fdt->close_on_exec->fds_bits[j];
set = fdt->close_on_exec[j];
if (!set)
continue;
fdt->close_on_exec->fds_bits[j] = 0;
fdt->close_on_exec[j] = 0;
spin_unlock(&files->file_lock);
for ( ; set ; i++,set >>= 1) {
if (set & 1) {