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Commit 01b2d93c authored Dec 22, 2006 by Vadim Lobanov Committed by Linus Torvalds Dec 22, 2006

[PATCH] fdtable: Provide free_fdtable() wrapper



Christoph Hellwig has expressed concerns that the recent fdtable changes
expose the details of the RCU methodology used to release no-longer-used
fdtable structures to the rest of the kernel.  The trivial patch below
addresses these concerns by introducing the appropriate free_fdtable()
calls, which simply wrap the release RCU usage.  Since free_fdtable() is a
one-liner, it makes sense to promote it to an inline helper.

Signed-off-by: Vadim Lobanov <vlobanov@speakeasy.net>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 31fccf7f

fs/file.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -206,7 +206,7 @@ static int expand_fdtable(struct files_struct *files, int nr)
	copy_fdtable(new_fdt, cur_fdt);		copy_fdtable(new_fdt, cur_fdt);
	rcu_assign_pointer(files->fdt, new_fdt);		rcu_assign_pointer(files->fdt, new_fdt);
	if (cur_fdt->max_fds > NR_OPEN_DEFAULT)		if (cur_fdt->max_fds > NR_OPEN_DEFAULT)
	call_rcu(&cur_fdt->rcu, free_fdtable_rcu);		free_fdtable(cur_fdt);
	} else {		} else {
	/* Somebody else expanded, so undo our attempt */		/* Somebody else expanded, so undo our attempt */
	free_fdarr(new_fdt);		free_fdarr(new_fdt);

include/linux/file.h

+5 −0

Original line number	Original line	Diff line number	Diff line
	@@ -80,6 +80,11 @@ extern int expand_files(struct files_struct *, int nr);
	extern void free_fdtable_rcu(struct rcu_head *rcu);		extern void free_fdtable_rcu(struct rcu_head *rcu);
	extern void __init files_defer_init(void);		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)		static inline struct file * fcheck_files(struct files_struct *files, unsigned int fd)
	{		{
	struct file * file = NULL;		struct file * file = NULL;

kernel/exit.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -468,7 +468,7 @@ void fastcall put_files_struct(struct files_struct *files)
	fdt = files_fdtable(files);		fdt = files_fdtable(files);
	if (fdt != &files->fdtab)		if (fdt != &files->fdtab)
	kmem_cache_free(files_cachep, files);		kmem_cache_free(files_cachep, files);
	call_rcu(&fdt->rcu, free_fdtable_rcu);		free_fdtable(fdt);
	}		}
	}		}