On Fri, Mar 16, 2012 at 04:38:20PM -0700, Greg KH wrote: > 3.2-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Pavel Shilovsky <[email protected]> > > commit d5751469f210d2149cc2159ffff66cbeef6da3f2 upstream. > > Reorganize the code to make the memory already allocated before > spinlock'ed loop. > > Reviewed-by: Jeff Layton <[email protected]> > Signed-off-by: Pavel Shilovsky <[email protected]> > Signed-off-by: Steve French <[email protected]> > Signed-off-by: Greg Kroah-Hartman <[email protected]> > > --- > fs/cifs/file.c | 69 > ++++++++++++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 56 insertions(+), 13 deletions(-) > > --- a/fs/cifs/file.c > +++ b/fs/cifs/file.c [....] > @@ -940,29 +950,55 @@ cifs_push_posix_locks(struct cifsFileInf > return rc; > } > > + lock_flocks(); > + cifs_for_each_lock(cfile->dentry->d_inode, before) { > + if ((*before)->fl_flags & FL_POSIX) > + count++; > + } > + unlock_flocks(); > + > INIT_LIST_HEAD(&locks_to_send); > > + /* > + * Allocating count locks is enough because no locks can be added to > + * the list while we are holding cinode->lock_mutex that protects > + * locking operations of this inode. > + */ > + for (; i < count; i++) { > + lck = kmalloc(sizeof(struct lock_to_push), GFP_KERNEL); > + if (!lck) { > + rc = -ENOMEM; > + goto err_out; > + } > + list_add_tail(&lck->llist, &locks_to_send); > + } > + > + i = 0; > + el = locks_to_send.next; > lock_flocks(); > cifs_for_each_lock(cfile->dentry->d_inode, before) { > + if (el == &locks_to_send) { > + /* something is really wrong */ > + cERROR(1, "Can't push all brlocks!"); > + break; > + } > flock = *before; > + if ((flock->fl_flags & FL_POSIX) == 0) > + continue; [...]
If I understand the logic correctly, el == &locks_to_send means we
already used all the lock_to_push structures. (It should also be
equivalent to testing i == count. Why is i incremented but not
otherwise used in the loop?)
But we test this before flock->fl_flags & FL_POSIX, which means we
don't know whether this lock actually needs to be assigned one of
those structures. So it appears that we might report a spurious error
if the lock list ends with a mandatory lock. If so, this is
relatively harmless but does need to be fixed.
Ben.
--
Ben Hutchings
We get into the habit of living before acquiring the habit of thinking.
- Albert Camus
signature.asc
Description: Digital signature
