From: Michael Ellerman <mpe@ellerman•id.au>
To: Dmitry Safonov <dima@arista•com>, linux-kernel@vger•kernel.org
Cc: Petr Mladek <pmladek@suse•com>, Dmitry Safonov <dima@arista•com>,
Tetsuo Handa <penguin-kernel@I-love•SAKURA.ne.jp>,
Greg Kroah-Hartman <gregkh@linuxfoundation•org>,
Dmitry Safonov <0x7f454c46@gmail•com>,
Steven Rostedt <rostedt@goodmis•org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail•com>,
Paul Mackerras <paulus@samba•org>, Jiri Slaby <jslaby@suse•com>,
Andrew Morton <akpm@linux-foundation•org>,
linuxppc-dev@lists•ozlabs.org, Ingo Molnar <mingo@kernel•org>
Subject: Re: [PATCHv2 26/50] powerpc: Add show_stack_loglvl()
Date: Thu, 19 Mar 2020 15:03:03 +1100 [thread overview]
Message-ID: <87blotdma0.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200316143916.195608-27-dima@arista.com>
Dmitry Safonov <dima@arista•com> writes:
> Currently, the log-level of show_stack() depends on a platform
> realization. It creates situations where the headers are printed with
> lower log level or higher than the stacktrace (depending on
> a platform or user).
>
> Furthermore, it forces the logic decision from user to an architecture
> side. In result, some users as sysrq/kdb/etc are doing tricks with
> temporary rising console_loglevel while printing their messages.
> And in result it not only may print unwanted messages from other CPUs,
> but also omit printing at all in the unlucky case where the printk()
> was deferred.
>
> Introducing log-level parameter and KERN_UNSUPPRESSED [1] seems
> an easier approach than introducing more printk buffers.
> Also, it will consolidate printings with headers.
>
> Introduce show_stack_loglvl(), that eventually will substitute
> show_stack().
>
> Cc: Benjamin Herrenschmidt <benh@kernel•crashing.org>
> Cc: Michael Ellerman <mpe@ellerman•id.au>
> Cc: Paul Mackerras <paulus@samba•org>
> Cc: linuxppc-dev@lists•ozlabs.org
> [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u
> Acked-by: Michael Ellerman <mpe@ellerman•id.au> (powerpc)
> Signed-off-by: Dmitry Safonov <dima@arista•com>
> ---
> arch/powerpc/kernel/process.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
Thanks for doing this, it has caused me problems in the past.
Acked-by: Michael Ellerman <mpe@ellerman•id.au> (powerpc)
cheers
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index fad50db9dcf2..c1ab7f613da4 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -2034,7 +2034,8 @@ unsigned long get_wchan(struct task_struct *p)
>
> static int kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
>
> -void show_stack(struct task_struct *tsk, unsigned long *stack)
> +void show_stack_loglvl(struct task_struct *tsk, unsigned long *stack,
> + const char *loglvl)
> {
> unsigned long sp, ip, lr, newsp;
> int count = 0;
> @@ -2059,7 +2060,7 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
> }
>
> lr = 0;
> - printk("Call Trace:\n");
> + printk("%sCall Trace:\n", loglvl);
> do {
> if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
> break;
> @@ -2068,7 +2069,8 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
> newsp = stack[0];
> ip = stack[STACK_FRAME_LR_SAVE];
> if (!firstframe || ip != lr) {
> - printk("["REG"] ["REG"] %pS", sp, ip, (void *)ip);
> + printk("%s["REG"] ["REG"] %pS",
> + loglvl, sp, ip, (void *)ip);
> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> ret_addr = ftrace_graph_ret_addr(current,
> &ftrace_idx, ip, stack);
> @@ -2090,8 +2092,9 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
> struct pt_regs *regs = (struct pt_regs *)
> (sp + STACK_FRAME_OVERHEAD);
> lr = regs->link;
> - printk("--- interrupt: %lx at %pS\n LR = %pS\n",
> - regs->trap, (void *)regs->nip, (void *)lr);
> + printk("%s--- interrupt: %lx at %pS\n LR = %pS\n",
> + loglvl, regs->trap,
> + (void *)regs->nip, (void *)lr);
> firstframe = 1;
> }
>
> @@ -2101,6 +2104,11 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
> put_task_stack(tsk);
> }
>
> +void show_stack(struct task_struct *tsk, unsigned long *stack)
> +{
> + show_stack_loglvl(tsk, stack, KERN_DEFAULT);
> +}
> +
> #ifdef CONFIG_PPC64
> /* Called with hard IRQs off */
> void notrace __ppc64_runlatch_on(void)
> --
> 2.25.1
prev parent reply other threads:[~2020-03-19 4:39 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-16 14:38 [PATCHv2 00/50] Add log level to show_stack() Dmitry Safonov
2020-03-16 14:38 ` [PATCHv2 26/50] powerpc: Add show_stack_loglvl() Dmitry Safonov
2020-03-19 4:03 ` Michael Ellerman [this message]
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