kernel debug: support resetting WARN_ONCE for all architectures
Some architectures store the WARN_ONCE state in the flags field of the
bug_entry. Clear that one too when resetting once state through
/sys/kernel/debug/clear_warn_once
Pointed out by Michael Ellerman
Improves the earlier patch that add clear_warn_once.
[ak@linux.intel.com: add a missing ifdef CONFIG_MODULES]
Link: http://lkml.kernel.org/r/20171020170633.9593-1-andi@firstfloor.org
[akpm@linux-foundation.org: fix unused var warning]
[akpm@linux-foundation.org: Use 0200 for clear_warn_once file, per mpe]
[akpm@linux-foundation.org: clear BUGFLAG_DONE in clear_once_table(), per mpe]
Link: http://lkml.kernel.org/r/20171019204642.7404-1-andi@firstfloor.org
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/bug.h b/include/linux/bug.h
index da4231c..fe59165 100644
--- a/include/linux/bug.h
+++ b/include/linux/bug.h
@@ -43,6 +43,8 @@
/* These are defined by the architecture */
int is_valid_bugaddr(unsigned long addr);
+void generic_bug_clear_once(void);
+
#else /* !CONFIG_GENERIC_BUG */
static inline enum bug_trap_type report_bug(unsigned long bug_addr,
@@ -51,6 +53,9 @@
return BUG_TRAP_TYPE_BUG;
}
+
+static inline void generic_bug_clear_once(void) {}
+
#endif /* CONFIG_GENERIC_BUG */
/*
diff --git a/kernel/panic.c b/kernel/panic.c
index 672a91d..67cebf2 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -595,6 +595,7 @@
static int clear_warn_once_set(void *data, u64 val)
{
+ generic_bug_clear_once();
memset(__start_once, 0, __end_once - __start_once);
return 0;
}
@@ -607,7 +608,7 @@
static __init int register_warn_debugfs(void)
{
/* Don't care about failure */
- debugfs_create_file("clear_warn_once", 0644, NULL,
+ debugfs_create_file("clear_warn_once", 0200, NULL,
NULL, &clear_warn_once_fops);
return 0;
}
diff --git a/lib/bug.c b/lib/bug.c
index 1e09440..f66be6b 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -196,3 +196,26 @@
return BUG_TRAP_TYPE_BUG;
}
+
+static void clear_once_table(struct bug_entry *start, struct bug_entry *end)
+{
+ struct bug_entry *bug;
+
+ for (bug = start; bug < end; bug++)
+ bug->flags &= ~BUGFLAG_DONE;
+}
+
+void generic_bug_clear_once(void)
+{
+#ifdef CONFIG_MODULES
+ struct module *mod;
+
+ rcu_read_lock_sched();
+ list_for_each_entry_rcu(mod, &module_bug_list, bug_list)
+ clear_once_table(mod->bug_table,
+ mod->bug_table + mod->num_bugs);
+ rcu_read_unlock_sched();
+#endif
+
+ clear_once_table(__start___bug_table, __stop___bug_table);
+}