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module: struct module_ref should contains long fields

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module_ref contains two "unsigned int" fields.

Thats now too small, since some machines can open more than 2^32 files.

Check commit 518de9b39e (fs: allow for more than 2^31 files) for
reference.

We can add an aligned(2 * sizeof(unsigned long)) attribute to force
alloc_percpu() allocating module_ref areas in single cache lines.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Tejun Heo <tj@kernel.org>
CC: Robin Holt <holt@sgi.com>
CC: David Miller <davem@davemloft.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Eric Dumazet 2012-01-13 09:32:14 +10:30 • committed by Rusty Russell
parent 48fd11880b
commit bd77c04772
3 changed files with 21 additions and 10 deletions
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21
include/linux/module.h
View file

@ -205,6 +205,20 @@ enum module_state
MODULE_STATE_GOING,
};
/**
* struct module_ref - per cpu module reference counts
* @incs: number of module get on this cpu
* @decs: number of module put on this cpu
*
* We force an alignment on 8 or 16 bytes, so that alloc_percpu()
* put @incs/@decs in same cache line, with no extra memory cost,
* since alloc_percpu() is fine grained.
*/
struct module_ref {
unsigned long incs;
unsigned long decs;
} __attribute((aligned(2 * sizeof(unsigned long))));
struct module
{
enum module_state state;
@ -347,10 +361,7 @@ struct module
/* Destruction function. */
void (*exit)(void);
struct module_ref {
unsigned int incs;
unsigned int decs;
} __percpu *refptr;
struct module_ref __percpu *refptr;
#endif
#ifdef CONFIG_CONSTRUCTORS
@ -434,7 +445,7 @@ extern void __module_put_and_exit(struct module *mod, long code)
#define module_put_and_exit(code) __module_put_and_exit(THIS_MODULE, code);
#ifdef CONFIG_MODULE_UNLOAD
unsigned int module_refcount(struct module *mod);
unsigned long module_refcount(struct module *mod);
void __symbol_put(const char *symbol);
#define symbol_put(x) __symbol_put(MODULE_SYMBOL_PREFIX #x)
void symbol_put_addr(void *addr);