Messages in this thread Patch in this message | | | Date | Sun, 14 Feb 2010 09:37:30 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH tip/core/rcu 07/13] vfs: apply lockdep-based checking to rcu_dereference() uses |
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On Sun, Feb 14, 2010 at 11:12:10AM +0100, Peter Zijlstra wrote: > On Thu, 2010-02-11 at 16:00 -0800, Paul E. McKenney wrote: > > > > -#define files_fdtable(files) (rcu_dereference((files)->fdt)) > > +#define files_fdtable(files) \ > > + (rcu_dereference_check((files)->fdt, \ > > + rcu_read_lock_held() || \ > > + lockdep_is_held(&(files)->file_lock) || > > \ > > + atomic_read(&files->count) == 1)) > > > > struct file_operations; > > struct vfsmount; > > @@ -78,7 +82,7 @@ static inline struct file * fcheck_files(struct files_struct *files, unsigned in > > struct fdtable *fdt = files_fdtable(files); > > > > if (fd < fdt->max_fds) > > - file = rcu_dereference(fdt->fd[fd]); > > + file = rcu_dereference_check(fdt->fd[fd], rcu_read_lock_held() || lockdep_is_held(&files->file_lock) || atomic_read(&files->count) == 1); > > return file; > > I'm almost thinking you can do something smart here and not replicate > that condition :-)
;-)
How about like the following? If this is agreeable, I will re-send the patch stack with this included.
Thanx, Paul
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vfs: abstract rcu_dereference_check for files-fdtable use
Create an rcu_dereference_check_fdtable() that encapsulates the rcu_dereference_check() condition for fcheck_files() use. This has the beneficial side-effect of getting rid of a very long line.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> ---
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index 144412f..013dc52 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -57,11 +57,14 @@ struct files_struct { struct file * fd_array[NR_OPEN_DEFAULT]; }; -#define files_fdtable(files) \ - (rcu_dereference_check((files)->fdt, \ +#define rcu_dereference_check_fdtable(files, fdtfd) \ + (rcu_dereference_check((fdtfd), \ rcu_read_lock_held() || \ lockdep_is_held(&(files)->file_lock) || \ - atomic_read(&files->count) == 1)) + atomic_read(&(files)->count) == 1)) + +#define files_fdtable(files) \ + (rcu_dereference_check_fdtable((files), (files)->fdt)) struct file_operations; struct vfsmount; @@ -82,7 +85,7 @@ static inline struct file * fcheck_files(struct files_struct *files, unsigned in struct fdtable *fdt = files_fdtable(files); if (fd < fdt->max_fds) - file = rcu_dereference_check(fdt->fd[fd], rcu_read_lock_held() || lockdep_is_held(&files->file_lock) || atomic_read(&files->count) == 1); + file = rcu_dereference_check_fdtable(files, fdt->fd[fd]); return file; }
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