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Commit aaf5dcfb authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
Browse files

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: default avatarAndi Kleen <ak@linux.intel.com>
Tested-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b1fca27d

include/linux/bug.h

+5 −0
Original line number Diff line number Diff line
@@ -43,6 +43,8 @@ enum bug_trap_type report_bug(unsigned long bug_addr, struct pt_regs *regs); 
/* 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 @@ static inline enum bug_trap_type report_bug(unsigned long bug_addr, 
	return BUG_TRAP_TYPE_BUG;

}





static inline void generic_bug_clear_once(void) {}



#endif	/* CONFIG_GENERIC_BUG */



/*

kernel/panic.c

+2 −1
Original line number Diff line number Diff line
@@ -595,6 +595,7 @@ EXPORT_SYMBOL(warn_slowpath_null); 


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 @@ DEFINE_SIMPLE_ATTRIBUTE(clear_warn_once_fops, 
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;

}

lib/bug.c

+23 −0
Original line number Diff line number Diff line
@@ -196,3 +196,26 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) 


	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);

}