From: Alexander Potapenko <glider@xxxxxxxxxx> Subject: printk: introduce dump_stack_lvl() dump_stack() is used for many different cases, which may require a log level consistent with other kernel messages surrounding the dump_stack() call. Without that, certain systems that are configured to ignore the default level messages will miss stack traces in critical error reports. This patch introduces dump_stack_lvl() that behaves similarly to dump_stack(), but accepts a custom log level. The old dump_stack() becomes equal to dump_stack_lvl(KERN_DEFAULT). A somewhat similar patch has been proposed in 2012: https://lore.kernel.org/lkml/1332493269.2359.9.camel@hebo/ , but wasn't merged. [elver@xxxxxxxxxx: add missing dump_stack_lvl() stub if CONFIG_PRINTK=n] Link: https://lkml.kernel.org/r/YJ0KAM0hQev1AmWe@xxxxxxxxxxxxxxxx Link: https://lkml.kernel.org/r/20210506105405.3535023-1-glider@xxxxxxxxxx Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Cc: Petr Mladek <pmladek@xxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: he, bo <bo.he@xxxxxxxxx> Cc: Yanmin Zhang <yanmin_zhang@xxxxxxxxxxxxxxx> Cc: Prasad Sodagudi <psodagud@xxxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/printk.h | 5 +++++ lib/dump_stack.c | 20 +++++++++++++------- 2 files changed, 18 insertions(+), 7 deletions(-) --- a/include/linux/printk.h~printk-introduce-dump_stack_lvl +++ a/include/linux/printk.h @@ -206,6 +206,7 @@ void __init setup_log_buf(int early); __printf(1, 2) void dump_stack_set_arch_desc(const char *fmt, ...); void dump_stack_print_info(const char *log_lvl); void show_regs_print_info(const char *log_lvl); +extern asmlinkage void dump_stack_lvl(const char *log_lvl) __cold; extern asmlinkage void dump_stack(void) __cold; extern void printk_safe_flush(void); extern void printk_safe_flush_on_panic(void); @@ -269,6 +270,10 @@ static inline void show_regs_print_info( { } +static inline void dump_stack_lvl(const char *log_lvl) +{ +} + static inline void dump_stack(void) { } --- a/lib/dump_stack.c~printk-introduce-dump_stack_lvl +++ a/lib/dump_stack.c @@ -73,10 +73,10 @@ void show_regs_print_info(const char *lo dump_stack_print_info(log_lvl); } -static void __dump_stack(void) +static void __dump_stack(const char *log_lvl) { - dump_stack_print_info(KERN_DEFAULT); - show_stack(NULL, NULL, KERN_DEFAULT); + dump_stack_print_info(log_lvl); + show_stack(NULL, NULL, log_lvl); } /** @@ -87,7 +87,7 @@ static void __dump_stack(void) #ifdef CONFIG_SMP static atomic_t dump_lock = ATOMIC_INIT(-1); -asmlinkage __visible void dump_stack(void) +asmlinkage __visible void dump_stack_lvl(const char *log_lvl) { unsigned long flags; int was_locked; @@ -117,7 +117,7 @@ retry: goto retry; } - __dump_stack(); + __dump_stack(log_lvl); if (!was_locked) atomic_set(&dump_lock, -1); @@ -125,9 +125,15 @@ retry: local_irq_restore(flags); } #else -asmlinkage __visible void dump_stack(void) +asmlinkage __visible void dump_stack_lvl(const char *log_lvl) { - __dump_stack(); + __dump_stack(log_lvl); } #endif +EXPORT_SYMBOL(dump_stack_lvl); + +asmlinkage __visible void dump_stack(void) +{ + dump_stack_lvl(KERN_DEFAULT); +} EXPORT_SYMBOL(dump_stack); _
