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author | Linus Torvalds <torvalds@linux-foundation.org> | 2010-06-05 17:17:36 (GMT) |
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committer | Rusty Russell <rusty@rustcorp.com.au> | 2010-06-05 01:47:37 (GMT) |
commit | 3bafeb6247042dcbb72b0141ec7c7107de9f0b99 (patch) | |
tree | f9b8f2437455332cd64d94bedb0836ac0f2b6fd9 /kernel/module.c | |
parent | 75676500f8298f0ee89db12db97294883c4b768e (diff) | |
download | linux-3bafeb6247042dcbb72b0141ec7c7107de9f0b99.tar.xz |
module: move find_module check to end
I think Rusty may have made the lock a bit _too_ finegrained there, and
didn't add it to some places that needed it. It looks, for example, like
PATCH 1/2 actually drops the lock in places where it's needed
("find_module()" is documented to need it, but now load_module() didn't
hold it at all when it did the find_module()).
Rather than adding a new "module_loading" list, I think we should be able
to just use the existing "modules" list, and just fix up the locking a
bit.
In fact, maybe we could just move the "look up existing module" a bit
later - optimistically assuming that the module doesn't exist, and then
just undoing the work if it turns out that we were wrong, just before
adding ourselves to the list.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'kernel/module.c')
-rw-r--r-- | kernel/module.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/module.c b/kernel/module.c index d293c21..2845004 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2226,11 +2226,6 @@ static noinline struct module *load_module(void __user *umod, goto free_mod; } - if (find_module(mod->name)) { - err = -EEXIST; - goto free_mod; - } - mod->state = MODULE_STATE_COMING; /* Allow arches to frob section contents and sizes. */ @@ -2509,6 +2504,12 @@ static noinline struct module *load_module(void __user *umod, * The mutex protects against concurrent writers. */ mutex_lock(&module_mutex); + if (find_module(mod->name)) { + err = -EEXIST; + /* This will also unlock the mutex */ + goto already_exists; + } + list_add_rcu(&mod->list, &modules); mutex_unlock(&module_mutex); @@ -2535,6 +2536,7 @@ static noinline struct module *load_module(void __user *umod, mutex_lock(&module_mutex); /* Unlink carefully: kallsyms could be walking list. */ list_del_rcu(&mod->list); + already_exists: mutex_unlock(&module_mutex); synchronize_sched(); module_arch_cleanup(mod); |