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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2014-11-10 09:28:29 +1030
committerRusty Russell <rusty@rustcorp.com.au>2014-11-11 17:07:46 +1030
commit0286b5ea125e58b4797747f688949c05394412e8 (patch)
treedef974e29b25f8a7a00da7b39f5b18bac93af98d /lib
parent461e34aed0550fee706a9a28fb453830b5079ea0 (diff)
lib/bug: Use RCU list ops for module_bug_list
Actually since module_bug_list should be used in BUG context, we may not need this. But for someone who want to use this from normal context, this makes module_bug_list an RCU list. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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

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