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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.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1266887105-1528-9-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
master
Paul E. McKenney 12 years ago
committed by Ingo Molnar
parent
commit
af61b96b4f
  1. 11
      include/linux/fdtable.h

11
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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