mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
synced 2025-10-31 06:18:54 +00:00
d7065da038
__aio_put_req() plays sick games with file refcount. What it wants is fput() from atomic context; it's almost always done with f_count > 1, so they only have to deal with delayed work in rare cases when their reference happens to be the last one. Current code decrements f_count and if it hasn't hit 0, everything is fine. Otherwise it keeps a pointer to struct file (with zero f_count!) around and has delayed work do __fput() on it. Better way to do it: use atomic_long_add_unless( , -1, 1) instead of !atomic_long_dec_and_test(). IOW, decrement it only if it's not the last reference, leave refcount alone if it was. And use normal fput() in delayed work. I've made that atomic_long_add_unless call a new helper - fput_atomic(). Drops a reference to file if it's safe to do in atomic (i.e. if that's not the last one), tells if it had been able to do that. aio.c converted to it, __fput() use is gone. req->ki_file *always* contributes to refcount now. And __fput() became static. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
42 lines
1.0 KiB
C
42 lines
1.0 KiB
C
/*
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* Wrapper functions for accessing the file_struct fd array.
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*/
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#ifndef __LINUX_FILE_H
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#define __LINUX_FILE_H
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <linux/posix_types.h>
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struct file;
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extern void fput(struct file *);
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extern void drop_file_write_access(struct file *file);
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struct file_operations;
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struct vfsmount;
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struct dentry;
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struct path;
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extern struct file *alloc_file(struct path *, fmode_t mode,
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const struct file_operations *fop);
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static inline void fput_light(struct file *file, int fput_needed)
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{
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if (unlikely(fput_needed))
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fput(file);
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}
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extern struct file *fget(unsigned int fd);
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extern struct file *fget_light(unsigned int fd, int *fput_needed);
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extern void set_close_on_exec(unsigned int fd, int flag);
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extern void put_filp(struct file *);
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extern int alloc_fd(unsigned start, unsigned flags);
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extern int get_unused_fd(void);
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#define get_unused_fd_flags(flags) alloc_fd(0, (flags))
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extern void put_unused_fd(unsigned int fd);
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extern void fd_install(unsigned int fd, struct file *file);
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#endif /* __LINUX_FILE_H */
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