af61b96b4f
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>
107 lines
2.5 KiB
C
107 lines
2.5 KiB
C
/*
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* descriptor table internals; you almost certainly want file.h instead.
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*/
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#ifndef __LINUX_FDTABLE_H
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#define __LINUX_FDTABLE_H
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#include <linux/posix_types.h>
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#include <linux/compiler.h>
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#include <linux/spinlock.h>
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#include <linux/rcupdate.h>
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#include <linux/types.h>
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#include <linux/init.h>
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#include <asm/atomic.h>
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/*
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* The default fd array needs to be at least BITS_PER_LONG,
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* as this is the granularity returned by copy_fdset().
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*/
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#define NR_OPEN_DEFAULT BITS_PER_LONG
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/*
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* The embedded_fd_set is a small fd_set,
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* suitable for most tasks (which open <= BITS_PER_LONG files)
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*/
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struct embedded_fd_set {
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unsigned long fds_bits[1];
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};
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struct fdtable {
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unsigned int max_fds;
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struct file ** fd; /* current fd array */
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fd_set *close_on_exec;
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fd_set *open_fds;
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struct rcu_head rcu;
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struct fdtable *next;
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};
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/*
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* Open file table structure
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*/
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struct files_struct {
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/*
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* read mostly part
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*/
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atomic_t count;
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struct fdtable *fdt;
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struct fdtable fdtab;
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/*
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* written part on a separate cache line in SMP
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*/
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spinlock_t file_lock ____cacheline_aligned_in_smp;
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int next_fd;
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struct embedded_fd_set close_on_exec_init;
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struct embedded_fd_set open_fds_init;
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struct file * fd_array[NR_OPEN_DEFAULT];
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};
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#define rcu_dereference_check_fdtable(files, fdtfd) \
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(rcu_dereference_check((fdtfd), \
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rcu_read_lock_held() || \
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lockdep_is_held(&(files)->file_lock) || \
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atomic_read(&(files)->count) == 1))
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#define files_fdtable(files) \
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(rcu_dereference_check_fdtable((files), (files)->fdt))
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struct file_operations;
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struct vfsmount;
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struct dentry;
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extern int expand_files(struct files_struct *, int nr);
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extern void free_fdtable_rcu(struct rcu_head *rcu);
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extern void __init files_defer_init(void);
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static inline void free_fdtable(struct fdtable *fdt)
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{
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call_rcu(&fdt->rcu, free_fdtable_rcu);
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}
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static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
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{
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struct file * file = NULL;
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struct fdtable *fdt = files_fdtable(files);
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if (fd < fdt->max_fds)
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file = rcu_dereference_check_fdtable(files, fdt->fd[fd]);
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return file;
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}
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/*
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* Check whether the specified fd has an open file.
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*/
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#define fcheck(fd) fcheck_files(current->files, fd)
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struct task_struct;
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struct files_struct *get_files_struct(struct task_struct *);
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void put_files_struct(struct files_struct *fs);
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void reset_files_struct(struct files_struct *);
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int unshare_files(struct files_struct **);
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struct files_struct *dup_fd(struct files_struct *, int *);
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extern struct kmem_cache *files_cachep;
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#endif /* __LINUX_FDTABLE_H */
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