mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-22 12:14:01 +08:00
1fd36adcd9
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>
131 lines
3.0 KiB
C
131 lines
3.0 KiB
C
/*
|
|
* descriptor table internals; you almost certainly want file.h instead.
|
|
*/
|
|
|
|
#ifndef __LINUX_FDTABLE_H
|
|
#define __LINUX_FDTABLE_H
|
|
|
|
#include <linux/posix_types.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/types.h>
|
|
#include <linux/init.h>
|
|
#include <linux/fs.h>
|
|
|
|
#include <linux/atomic.h>
|
|
|
|
/*
|
|
* The default fd array needs to be at least BITS_PER_LONG,
|
|
* as this is the granularity returned by copy_fdset().
|
|
*/
|
|
#define NR_OPEN_DEFAULT BITS_PER_LONG
|
|
|
|
struct fdtable {
|
|
unsigned int max_fds;
|
|
struct file __rcu **fd; /* current fd array */
|
|
unsigned long *close_on_exec;
|
|
unsigned long *open_fds;
|
|
struct rcu_head rcu;
|
|
struct fdtable *next;
|
|
};
|
|
|
|
static inline void __set_close_on_exec(int fd, struct fdtable *fdt)
|
|
{
|
|
__set_bit(fd, fdt->close_on_exec);
|
|
}
|
|
|
|
static inline void __clear_close_on_exec(int fd, struct fdtable *fdt)
|
|
{
|
|
__clear_bit(fd, fdt->close_on_exec);
|
|
}
|
|
|
|
static inline bool close_on_exec(int fd, const struct fdtable *fdt)
|
|
{
|
|
return test_bit(fd, fdt->close_on_exec);
|
|
}
|
|
|
|
static inline void __set_open_fd(int fd, struct fdtable *fdt)
|
|
{
|
|
__set_bit(fd, fdt->open_fds);
|
|
}
|
|
|
|
static inline void __clear_open_fd(int fd, struct fdtable *fdt)
|
|
{
|
|
__clear_bit(fd, fdt->open_fds);
|
|
}
|
|
|
|
static inline bool fd_is_open(int fd, const struct fdtable *fdt)
|
|
{
|
|
return test_bit(fd, fdt->open_fds);
|
|
}
|
|
|
|
/*
|
|
* Open file table structure
|
|
*/
|
|
struct files_struct {
|
|
/*
|
|
* read mostly part
|
|
*/
|
|
atomic_t count;
|
|
struct fdtable __rcu *fdt;
|
|
struct fdtable fdtab;
|
|
/*
|
|
* written part on a separate cache line in SMP
|
|
*/
|
|
spinlock_t file_lock ____cacheline_aligned_in_smp;
|
|
int next_fd;
|
|
unsigned long close_on_exec_init[1];
|
|
unsigned long open_fds_init[1];
|
|
struct file __rcu * fd_array[NR_OPEN_DEFAULT];
|
|
};
|
|
|
|
#define rcu_dereference_check_fdtable(files, fdtfd) \
|
|
(rcu_dereference_check((fdtfd), \
|
|
lockdep_is_held(&(files)->file_lock) || \
|
|
atomic_read(&(files)->count) == 1 || \
|
|
rcu_my_thread_group_empty()))
|
|
|
|
#define files_fdtable(files) \
|
|
(rcu_dereference_check_fdtable((files), (files)->fdt))
|
|
|
|
struct file_operations;
|
|
struct vfsmount;
|
|
struct dentry;
|
|
|
|
extern int expand_files(struct files_struct *, int nr);
|
|
extern void free_fdtable_rcu(struct rcu_head *rcu);
|
|
extern void __init files_defer_init(void);
|
|
|
|
static inline void free_fdtable(struct fdtable *fdt)
|
|
{
|
|
call_rcu(&fdt->rcu, free_fdtable_rcu);
|
|
}
|
|
|
|
static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
|
|
{
|
|
struct file * file = NULL;
|
|
struct fdtable *fdt = files_fdtable(files);
|
|
|
|
if (fd < fdt->max_fds)
|
|
file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
|
|
return file;
|
|
}
|
|
|
|
/*
|
|
* Check whether the specified fd has an open file.
|
|
*/
|
|
#define fcheck(fd) fcheck_files(current->files, fd)
|
|
|
|
struct task_struct;
|
|
|
|
struct files_struct *get_files_struct(struct task_struct *);
|
|
void put_files_struct(struct files_struct *fs);
|
|
void reset_files_struct(struct files_struct *);
|
|
int unshare_files(struct files_struct **);
|
|
struct files_struct *dup_fd(struct files_struct *, int *);
|
|
|
|
extern struct kmem_cache *files_cachep;
|
|
|
|
#endif /* __LINUX_FDTABLE_H */
|