5.4-stable review patch. If anyone has any objections, please let me know.
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From: Dmitry Safonov dima@arista.com
[ Upstream commit 1ad87824f4cf16a7f381e1f94943a96bb7a99062 ]
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().
[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u
Signed-off-by: Dmitry Safonov dima@arista.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Cc: Anton Ivanov anton.ivanov@cambridgegreys.com Cc: Jeff Dike jdike@addtoit.com Cc: Richard Weinberger richard@nod.at Link: http://lkml.kernel.org/r/20200418201944.482088-37-dima@arista.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Stable-dep-of: 0f659ff362ea ("um: Always dump trace for specified task in show_stack") Signed-off-by: Sasha Levin sashal@kernel.org --- arch/um/kernel/sysrq.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-)
diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c index c831a1c2eb94a..1b54b6431499b 100644 --- a/arch/um/kernel/sysrq.c +++ b/arch/um/kernel/sysrq.c @@ -17,7 +17,9 @@
static void _print_addr(void *data, unsigned long address, int reliable) { - pr_info(" [<%08lx>] %s%pS\n", address, reliable ? "" : "? ", + const char *loglvl = data; + + printk("%s [<%08lx>] %s%pS\n", loglvl, address, reliable ? "" : "? ", (void *)address); }
@@ -25,7 +27,8 @@ static const struct stacktrace_ops stackops = { .address = _print_addr };
-void show_stack(struct task_struct *task, unsigned long *stack) +void show_stack_loglvl(struct task_struct *task, unsigned long *stack, + const char *loglvl) { struct pt_regs *segv_regs = current->thread.segv_regs; int i; @@ -39,17 +42,22 @@ void show_stack(struct task_struct *task, unsigned long *stack) if (!stack) stack = get_stack_pointer(task, segv_regs);
- pr_info("Stack:\n"); + printk("%sStack:\n", loglvl); for (i = 0; i < 3 * STACKSLOTS_PER_LINE; i++) { if (kstack_end(stack)) break; if (i && ((i % STACKSLOTS_PER_LINE) == 0)) - pr_cont("\n"); + printk("%s\n", loglvl); pr_cont(" %08lx", *stack++); } - pr_cont("\n"); + printk("%s\n", loglvl); + + printk("%sCall Trace:\n", loglvl); + dump_trace(current, &stackops, (void *)loglvl); + printk("%s\n", loglvl); +}
- pr_info("Call Trace:\n"); - dump_trace(current, &stackops, NULL); - pr_info("\n"); +void show_stack(struct task_struct *task, unsigned long *stack) +{ + show_stack_loglvl(task, stack, KERN_INFO); }