Commit 01b2d93c authored by Vadim Lobanov's avatar Vadim Lobanov Committed by Linus Torvalds
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[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: default avatarVadim Lobanov <vlobanov@speakeasy.net>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus 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);

	}

	}

}

}

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