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Merge tag 'printk-for-5.8-kdb-nmi' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

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Pull printk fix from Petr Mladek:
 "One more printk change for 5.8: make sure that messages printed from
  KDB context are redirected to KDB console handlers. It did not work
  when KDB interrupted NMI or printk_safe contexts.

  Arm people started hitting this problem more often recently. I forgot
  to add the fix into the previous pull request by mistake"

* tag 'printk-for-5.8-kdb-nmi' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  printk/kdb: Redirect printk messages into kdb in any context
This commit is contained in:
Linus Torvalds
2020-06-12 12:13:36 -07:00
parent 923ea1631e 2a9e5ded95
commit 5c2fb57af0
2 changed files with 8 additions and 13 deletions
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14
kernel/printk/printk.c
View File

@@ -35,7 +35,6 @@
#include <linux/memblock.h>
#include <linux/syscalls.h>
#include <linux/crash_core.h>
#include <linux/kdb.h>
#include <linux/ratelimit.h>
#include <linux/kmsg_dump.h>
#include <linux/syslog.h>
@@ -2047,18 +2046,7 @@ EXPORT_SYMBOL(vprintk);
int vprintk_default(const char *fmt, va_list args)
{
int r;
#ifdef CONFIG_KGDB_KDB
/* Allow to pass printk() to kdb but avoid a recursion. */
if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0)) {
r = vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
return r;
}
#endif
r = vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
return r;
return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
}
EXPORT_SYMBOL_GPL(vprintk_default);

7
kernel/printk/printk_safe.c
View File

@@ -6,6 +6,7 @@
#include <linux/preempt.h>
#include <linux/spinlock.h>
#include <linux/debug_locks.h>
#include <linux/kdb.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/irq_work.h>
@@ -360,6 +361,12 @@ void __printk_safe_exit(void)
__printf(1, 0) int vprintk_func(const char *fmt, va_list args)
{
#ifdef CONFIG_KGDB_KDB
/* Allow to pass printk() to kdb but avoid a recursion. */
if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0))
return vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);
#endif
/*
* Try to use the main logbuf even in NMI. But avoid calling console
* drivers that might have their own locks.