Merge branch 'master' of ssh://gparabola/srv/git/abslibre

1 files changed, 77 insertions, 0 deletions

diff --git a/kernels/linux-libre-lts-rt/module-init-wait-3.0.patch b/kernels/linux-libre-lts-rt/module-init-wait-3.0.patch
new file mode 100644
index 000000000..1bcfd2491
--- /dev/null
+++ b/kernels/linux-libre-lts-rt/module-init-wait-3.0.patch
@@ -0,0 +1,77 @@
+From: Rusty Russell <rusty@rustcorp.com.au>
+Date: Fri, 28 Sep 2012 05:01:03 +0000 (+0930)
+Subject: module: wait when loading a module which is currently initializing.
+X-Git-Tag: v3.7-rc1~2^2~32
+X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=9bb9c3be568346538
+
+module: wait when loading a module which is currently initializing.
+
+The original module-init-tools module loader used a fnctl lock on the
+.ko file to avoid attempts to simultaneously load a module.
+Unfortunately, you can't get an exclusive fcntl lock on a read-only
+fd, making this not work for read-only mounted filesystems.
+module-init-tools has a hacky sleep-and-loop for this now.
+
+It's not that hard to wait in the kernel, and only return -EEXIST once
+the first module has finished loading (or continue loading the module
+if the first one failed to initialize for some reason).  It's also
+consistent with what we do for dependent modules which are still loading.
+
+Suggested-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
+Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
+---
+
+diff --git a/kernel/module.c b/kernel/module.c
+index 63cf6e7..74bc195 100644
+--- a/kernel/module.c
++++ b/kernel/module.c
+@@ -2845,6 +2845,20 @@ static int post_relocation(struct module *mod, const struct load_info *info)
+ 	return module_finalize(info->hdr, info->sechdrs, mod);
+ }
+ 
++/* Is this module of this name done loading?  No locks held. */
++static bool finished_loading(const char *name)
++{
++	struct module *mod;
++	bool ret;
++
++	mutex_lock(&module_mutex);
++	mod = find_module(name);
++	ret = !mod || mod->state != MODULE_STATE_COMING;
++	mutex_unlock(&module_mutex);
++
++	return ret;
++}
++
+ /* Allocate and load the module: note that size of section 0 is always
+    zero, and we rely on this for optional sections. */
+ static struct module *load_module(void __user *umod,
+@@ -2852,7 +2866,7 @@ static struct module *load_module(void __user *umod,
+ 				  const char __user *uargs)
+ {
+ 	struct load_info info = { NULL, };
+-	struct module *mod;
++	struct module *mod, *old;
+ 	long err;
+ 
+ 	pr_debug("load_module: umod=%p, len=%lu, uargs=%p\n",
+@@ -2918,8 +2932,18 @@ static struct module *load_module(void __user *umod,
+ 	 * function to insert in a way safe to concurrent readers.
+ 	 * The mutex protects against concurrent writers.
+ 	 */
++again:
+ 	mutex_lock(&module_mutex);
+-	if (find_module(mod->name)) {
++	if ((old = find_module(mod->name)) != NULL) {
++		if (old->state == MODULE_STATE_COMING) {
++			/* Wait in case it fails to load. */
++			mutex_unlock(&module_mutex);
++			err = wait_event_interruptible(module_wq,
++					       finished_loading(mod->name));
++			if (err)
++				goto free_arch_cleanup;
++			goto again;
++		}
+ 		err = -EEXIST;
+ 		goto unlock;
+ 	}