78 lines
2.7 KiB
Diff
78 lines
2.7 KiB
Diff
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From: Rusty Russell <rusty@rustcorp.com.au>
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Date: Fri, 28 Sep 2012 05:01:03 +0000 (+0930)
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Subject: module: wait when loading a module which is currently initializing.
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X-Git-Tag: v3.7-rc1~2^2~32
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=9bb9c3be568346538
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module: wait when loading a module which is currently initializing.
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The original module-init-tools module loader used a fnctl lock on the
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.ko file to avoid attempts to simultaneously load a module.
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Unfortunately, you can't get an exclusive fcntl lock on a read-only
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fd, making this not work for read-only mounted filesystems.
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module-init-tools has a hacky sleep-and-loop for this now.
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It's not that hard to wait in the kernel, and only return -EEXIST once
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the first module has finished loading (or continue loading the module
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if the first one failed to initialize for some reason). It's also
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consistent with what we do for dependent modules which are still loading.
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Suggested-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
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Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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---
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diff --git a/kernel/module.c b/kernel/module.c
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index 63cf6e7..74bc195 100644
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--- a/kernel/module.c
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+++ b/kernel/module.c
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@@ -2845,6 +2845,20 @@ static int post_relocation(struct module *mod, const struct load_info *info)
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return module_finalize(info->hdr, info->sechdrs, mod);
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}
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+/* Is this module of this name done loading? No locks held. */
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+static bool finished_loading(const char *name)
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+{
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+ struct module *mod;
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+ bool ret;
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+
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+ mutex_lock(&module_mutex);
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+ mod = find_module(name);
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+ ret = !mod || mod->state != MODULE_STATE_COMING;
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+ mutex_unlock(&module_mutex);
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+
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+ return ret;
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+}
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+
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/* Allocate and load the module: note that size of section 0 is always
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zero, and we rely on this for optional sections. */
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static struct module *load_module(void __user *umod,
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@@ -2852,7 +2866,7 @@ static struct module *load_module(void __user *umod,
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const char __user *uargs)
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{
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struct load_info info = { NULL, };
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- struct module *mod;
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+ struct module *mod, *old;
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long err;
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pr_debug("load_module: umod=%p, len=%lu, uargs=%p\n",
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@@ -2918,8 +2932,18 @@ static struct module *load_module(void __user *umod,
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* function to insert in a way safe to concurrent readers.
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* The mutex protects against concurrent writers.
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*/
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+again:
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mutex_lock(&module_mutex);
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- if (find_module(mod->name)) {
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+ if ((old = find_module(mod->name)) != NULL) {
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+ if (old->state == MODULE_STATE_COMING) {
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+ /* Wait in case it fails to load. */
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+ mutex_unlock(&module_mutex);
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+ err = wait_event_interruptible(module_wq,
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+ finished_loading(mod->name));
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+ if (err)
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+ goto free_arch_cleanup;
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+ goto again;
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+ }
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err = -EEXIST;
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goto unlock;
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}
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