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kernel debug: support resetting WARN_ONCE for all architectures

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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>
This commit is contained in:
Andi Kleen 2017-11-17 15:27:06 -08:00 • committed by Linus Torvalds
parent b1fca27d38
commit aaf5dcfb22
3 changed files with 30 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

5
include/linux/bug.h
View file

@ -43,6 +43,8 @@ enum bug_trap_type report_bug(unsigned long bug_addr, struct pt_regs *regs);
/* These are defined by the architecture */ /* These are defined by the architecture */
int is_valid_bugaddr(unsigned long addr); int is_valid_bugaddr(unsigned long addr);
void generic_bug_clear_once(void);
#else /* !CONFIG_GENERIC_BUG */ #else /* !CONFIG_GENERIC_BUG */
static inline enum bug_trap_type report_bug(unsigned long bug_addr, static inline enum bug_trap_type report_bug(unsigned long bug_addr,
@ -51,6 +53,9 @@ static inline enum bug_trap_type report_bug(unsigned long bug_addr,
return BUG_TRAP_TYPE_BUG; return BUG_TRAP_TYPE_BUG;
} }
static inline void generic_bug_clear_once(void) {}
#endif /* CONFIG_GENERIC_BUG */ #endif /* CONFIG_GENERIC_BUG */
/* /*

3
kernel/panic.c
View file

@ -595,6 +595,7 @@ EXPORT_SYMBOL(warn_slowpath_null);
static int clear_warn_once_set(void *data, u64 val) static int clear_warn_once_set(void *data, u64 val)
{ {
generic_bug_clear_once();
memset(__start_once, 0, __end_once - __start_once); memset(__start_once, 0, __end_once - __start_once);
return 0; return 0;
} }
@ -607,7 +608,7 @@ DEFINE_SIMPLE_ATTRIBUTE(clear_warn_once_fops,
static __init int register_warn_debugfs(void) static __init int register_warn_debugfs(void)
{ {
/* Don't care about failure */ /* 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); NULL, &clear_warn_once_fops);
return 0; return 0;
} }

23
lib/bug.c
View file

@ -196,3 +196,26 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
return BUG_TRAP_TYPE_BUG; 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);
}