show_trace_log_lvl() provides x86 platform-specific way to unwind backtrace with a given log level. Unfortunately, registers dump(s) are not printed with the same log level - instead, KERN_DEFAULT is always used.
Arista's switches uses quite common setup with rsyslog, where only urgent messages goes to console (console_log_level=KERN_ERR), everything else goes into /var/log/ as the console baud-rate often is indecently slow (9600 bps). Backtrace dumps without registers printed have proven to be as useful as morning standups. Furthermore, in order to introduce KERN_UNSUPPRESSED (which I believe is still the most elegant way to fix raciness of sysrq[1]) the log level should be passed down the stack to register dumping functions. Besides, I have a potential use-case for printing traces with KERN_DEBUG level [2] (where registers dump shouldn't appear with higher log level). After all preparations are done, provide log_lvl parameter for show_regs_if_on_stack() and wire up to actual log level used as an argument for show_trace_log_lvl(). [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-d...@arista.com/ [2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-d...@arista.com/ Acked-by: Petr Mladek <pmla...@suse.com> Signed-off-by: Dmitry Safonov <d...@arista.com> --- arch/x86/kernel/dumpstack.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 4954d6678cef..f9a3526af15d 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -134,7 +134,7 @@ void show_iret_regs(struct pt_regs *regs, const char *log_lvl) } static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, - bool partial) + bool partial, const char *log_lvl) { /* * These on_stack() checks aren't strictly necessary: the unwind code @@ -146,7 +146,7 @@ static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, * they can be printed in the right context. */ if (!partial && on_stack(info, regs, sizeof(*regs))) { - __show_regs(regs, SHOW_REGS_SHORT, KERN_DEFAULT); + __show_regs(regs, SHOW_REGS_SHORT, log_lvl); } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET, IRET_FRAME_SIZE)) { @@ -155,7 +155,7 @@ static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, * full pt_regs might not have been saved yet. In that case * just print the iret frame. */ - show_iret_regs(regs, KERN_DEFAULT); + show_iret_regs(regs, log_lvl); } } @@ -210,7 +210,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, printk("%s <%s>\n", log_lvl, stack_name); if (regs) - show_regs_if_on_stack(&stack_info, regs, partial); + show_regs_if_on_stack(&stack_info, regs, partial, log_lvl); /* * Scan the stack, printing any text addresses we find. At the @@ -271,7 +271,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, /* if the frame has entry regs, print them */ regs = unwind_get_entry_regs(&state, &partial); if (regs) - show_regs_if_on_stack(&stack_info, regs, partial); + show_regs_if_on_stack(&stack_info, regs, partial, log_lvl); } if (stack_name) -- 2.27.0
