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| author | Peter Zijlstra <peterz@infradead.org> | 2017-02-25 08:56:53 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-03-30 09:37:20 +0200 |
| commit | 19d436268dde95389c616bb3819da73f0a8b28a8 (patch) | |
| tree | bd08a3466744511ad2d07edd5e9be4161cfb56e2 /lib/bug.c | |
| parent | 70579a86e3c8eb2ce57999e594a73b4dfe095959 (diff) | |
| download | linux-19d436268dde95389c616bb3819da73f0a8b28a8.tar.gz linux-19d436268dde95389c616bb3819da73f0a8b28a8.tar.bz2 linux-19d436268dde95389c616bb3819da73f0a8b28a8.zip | |
debug: Add _ONCE() logic to report_bug()
Josh suggested moving the _ONCE logic inside the trap handler, using a
bit in the bug_entry::flags field, avoiding the need for the extra
variable.
Sadly this only works for WARN_ON_ONCE(), since the others have
printk() statements prior to triggering the trap.
Still, this saves a fair amount of text and some data:
text data filename
10682460 4530992 defconfig-build/vmlinux.orig
10665111 4530096 defconfig-build/vmlinux.patched
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'lib/bug.c')
| -rw-r--r-- | lib/bug.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/lib/bug.c b/lib/bug.c index 06edbbef0623..a6a1137d06db 100644 --- a/lib/bug.c +++ b/lib/bug.c @@ -47,7 +47,7 @@ #include <linux/sched.h> #include <linux/rculist.h> -extern const struct bug_entry __start___bug_table[], __stop___bug_table[]; +extern struct bug_entry __start___bug_table[], __stop___bug_table[]; static inline unsigned long bug_addr(const struct bug_entry *bug) { @@ -62,10 +62,10 @@ static inline unsigned long bug_addr(const struct bug_entry *bug) /* Updates are protected by module mutex */ static LIST_HEAD(module_bug_list); -static const struct bug_entry *module_find_bug(unsigned long bugaddr) +static struct bug_entry *module_find_bug(unsigned long bugaddr) { struct module *mod; - const struct bug_entry *bug = NULL; + struct bug_entry *bug = NULL; rcu_read_lock_sched(); list_for_each_entry_rcu(mod, &module_bug_list, bug_list) { @@ -122,15 +122,15 @@ void module_bug_cleanup(struct module *mod) #else -static inline const struct bug_entry *module_find_bug(unsigned long bugaddr) +static inline struct bug_entry *module_find_bug(unsigned long bugaddr) { return NULL; } #endif -const struct bug_entry *find_bug(unsigned long bugaddr) +struct bug_entry *find_bug(unsigned long bugaddr) { - const struct bug_entry *bug; + struct bug_entry *bug; for (bug = __start___bug_table; bug < __stop___bug_table; ++bug) if (bugaddr == bug_addr(bug)) @@ -141,9 +141,9 @@ const struct bug_entry *find_bug(unsigned long bugaddr) enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) { - const struct bug_entry *bug; + struct bug_entry *bug; const char *file; - unsigned line, warning; + unsigned line, warning, once, done; if (!is_valid_bugaddr(bugaddr)) return BUG_TRAP_TYPE_NONE; @@ -164,6 +164,18 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) line = bug->line; #endif warning = (bug->flags & BUGFLAG_WARNING) != 0; + once = (bug->flags & BUGFLAG_ONCE) != 0; + done = (bug->flags & BUGFLAG_DONE) != 0; + + if (warning && once) { + if (done) + return BUG_TRAP_TYPE_WARN; + + /* + * Since this is the only store, concurrency is not an issue. + */ + bug->flags |= BUGFLAG_DONE; + } } if (warning) { |