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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /kernel/printk/printk_safe.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | kernel/printk/printk_safe.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c new file mode 100644 index 000000000..6d10927a0 --- /dev/null +++ b/kernel/printk/printk_safe.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * printk_safe.c - Safe printk for printk-deadlock-prone contexts + */ + +#include <linux/preempt.h> +#include <linux/kdb.h> +#include <linux/smp.h> +#include <linux/cpumask.h> +#include <linux/printk.h> +#include <linux/kprobes.h> + +#include "internal.h" + +static DEFINE_PER_CPU(int, printk_context); + +/* Can be preempted by NMI. */ +void __printk_safe_enter(void) +{ + this_cpu_inc(printk_context); +} + +/* Can be preempted by NMI. */ +void __printk_safe_exit(void) +{ + this_cpu_dec(printk_context); +} + +asmlinkage int vprintk(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 + + /* + * Use the main logbuf even in NMI. But avoid calling console + * drivers that might have their own locks. + */ + if (this_cpu_read(printk_context) || in_nmi()) + return vprintk_deferred(fmt, args); + + /* No obstacles. */ + return vprintk_default(fmt, args); +} +EXPORT_SYMBOL(vprintk); |