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Subject[PATCH] __try_module_get()
Date
Linus, please apply.

Name: __try_module_get
Author: Rusty Russell
Status: Trivial

D: Introduces __try_module_get for places where we know we already hold
D: a reference and ignoring the fact that the module is being "rmmod --wait"ed
D: is simpler.

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .5936-linux-2.5.66-bk2/fs/filesystems.c .5936-linux-2.5.66-bk2.updated/fs/filesystems.c
--- .5936-linux-2.5.66-bk2/fs/filesystems.c 2003-03-18 12:21:38.000000000 +1100
+++ .5936-linux-2.5.66-bk2.updated/fs/filesystems.c 2003-03-27 12:58:34.000000000 +1100
@@ -32,17 +32,7 @@ static rwlock_t file_systems_lock = RW_L
/* WARNING: This can be used only if we _already_ own a reference */
void get_filesystem(struct file_system_type *fs)
{
- if (!try_module_get(fs->owner)) {
-#ifdef CONFIG_MODULE_UNLOAD
- unsigned int cpu = get_cpu();
- local_inc(&fs->owner->ref[cpu].count);
- put_cpu();
-#else
- /* Getting filesystem while it's starting up? We're
- already supposed to have a reference. */
- BUG();
-#endif
- }
+ __try_module_get(fs->owner);
}

void put_filesystem(struct file_system_type *fs)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .5936-linux-2.5.66-bk2/include/linux/module.h .5936-linux-2.5.66-bk2.updated/include/linux/module.h
--- .5936-linux-2.5.66-bk2/include/linux/module.h 2003-03-25 12:17:31.000000000 +1100
+++ .5936-linux-2.5.66-bk2.updated/include/linux/module.h 2003-03-27 12:58:34.000000000 +1100
@@ -272,6 +272,7 @@ int module_text_address(unsigned long ad

#ifdef CONFIG_MODULE_UNLOAD

+unsigned int 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);
@@ -282,6 +283,17 @@ void symbol_put_addr(void *addr);
#define local_dec(x) atomic_dec(x)
#endif

+/* Sometimes we know we already have a refcount, and it's easier not
+ to handle the error case (which only happens with rmmod --wait). */
+static inline void __try_module_get(struct module *module)
+{
+ if (module) {
+ BUG_ON(module_refcount(module) == 0);
+ local_inc(&module->ref[get_cpu()].count);
+ put_cpu();
+ }
+}
+
static inline int try_module_get(struct module *module)
{
int ret = 1;
@@ -317,6 +329,9 @@ static inline int try_module_get(struct
static inline void module_put(struct module *module)
{
}
+static inline void __try_module_get(struct module *module)
+{
+}
#define symbol_put(x) do { } while(0)
#define symbol_put_addr(p) do { } while(0)

@@ -371,6 +386,10 @@ static inline int module_text_address(un
#define symbol_put(x) do { } while(0)
#define symbol_put_addr(x) do { } while(0)

+static inline void __try_module_get(struct module *module)
+{
+}
+
static inline int try_module_get(struct module *module)
{
return 1;
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .5936-linux-2.5.66-bk2/kernel/module.c .5936-linux-2.5.66-bk2.updated/kernel/module.c
--- .5936-linux-2.5.66-bk2/kernel/module.c 2003-03-18 05:01:52.000000000 +1100
+++ .5936-linux-2.5.66-bk2.updated/kernel/module.c 2003-03-27 12:59:06.000000000 +1100
@@ -374,7 +374,7 @@ static inline void restart_refcounts(voi
}
#endif

-static unsigned int module_refcount(struct module *mod)
+unsigned int module_refcount(struct module *mod)
{
unsigned int i, total = 0;

@@ -382,6 +382,7 @@ static unsigned int module_refcount(stru
total += atomic_read(&mod->ref[i].count);
return total;
}
+EXPORT_SYMBOL(module_refcount);

/* This exists whether we can unload or not */
static void free_module(struct module *mod);
--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.

-
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