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authorLinus Torvalds <torvalds@linux-foundation.org>2014-12-18 20:55:41 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-18 20:55:41 -0800
commitd790be3863b28fd22e0781c1a3ddefcbfd5f7086 (patch)
tree56a9f83b66f336df73ff81d13a14a2d63ed4c0db /lib
parent64ec45bff6b3dade2643ed4c0f688a15ecf46ea2 (diff)
parentb0a65b0cccd477b2fd8b7adad0ac39433df54829 (diff)
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Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
Pull module updates from Rusty Russell: "The exciting thing here is the getting rid of stop_machine on module removal. This is possible by using a simple atomic_t for the counter, rather than our fancy per-cpu counter: it turns out that no one is doing a module increment per net packet, so the slowdown should be in the noise" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: param: do not set store func without write perm params: cleanup sysfs allocation kernel:module Fix coding style errors and warnings. module: Remove stop_machine from module unloading module: Replace module_ref with atomic_t refcnt lib/bug: Use RCU list ops for module_bug_list module: Unlink module with RCU synchronizing instead of stop_machine module: Wait for RCU synchronizing before releasing a module
Diffstat (limited to 'lib')
-rw-r--r--lib/bug.c20
1 files changed, 14 insertions, 6 deletions
diff --git a/lib/bug.c b/lib/bug.c
index d1d7c7878900..0c3bd9552b6f 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -64,16 +64,22 @@ static LIST_HEAD(module_bug_list);
static const struct bug_entry *module_find_bug(unsigned long bugaddr)
{
struct module *mod;
+ const struct bug_entry *bug = NULL;
- list_for_each_entry(mod, &module_bug_list, bug_list) {
- const struct bug_entry *bug = mod->bug_table;
+ rcu_read_lock();
+ list_for_each_entry_rcu(mod, &module_bug_list, bug_list) {
unsigned i;
+ bug = mod->bug_table;
for (i = 0; i < mod->num_bugs; ++i, ++bug)
if (bugaddr == bug_addr(bug))
- return bug;
+ goto out;
}
- return NULL;
+ bug = NULL;
+out:
+ rcu_read_unlock();
+
+ return bug;
}
void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
@@ -99,13 +105,15 @@ void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
* Strictly speaking this should have a spinlock to protect against
* traversals, but since we only traverse on BUG()s, a spinlock
* could potentially lead to deadlock and thus be counter-productive.
+ * Thus, this uses RCU to safely manipulate the bug list, since BUG
+ * must run in non-interruptive state.
*/
- list_add(&mod->bug_list, &module_bug_list);
+ list_add_rcu(&mod->bug_list, &module_bug_list);
}
void module_bug_cleanup(struct module *mod)
{
- list_del(&mod->bug_list);
+ list_del_rcu(&mod->bug_list);
}
#else