diff options
| -rw-r--r-- | drivers/tty/serial/cpm_uart/cpm_uart_core.c | 2 | ||||
| -rw-r--r-- | drivers/tty/sysrq.c | 23 | ||||
| -rw-r--r-- | include/linux/sysrq.h | 5 | ||||
| -rw-r--r-- | kernel/printk.c | 5 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 22 |
5 files changed, 54 insertions, 3 deletions
diff --git a/drivers/tty/serial/cpm_uart/cpm_uart_core.c b/drivers/tty/serial/cpm_uart/cpm_uart_core.c index b418947b7107..a8b05594e468 100644 --- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c +++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c @@ -1226,7 +1226,7 @@ static void cpm_uart_console_write(struct console *co, const char *s, { struct uart_cpm_port *pinfo = &cpm_uart_ports[co->index]; unsigned long flags; - int nolock = oops_in_progress; + int nolock = oops_in_progress || sysrq_in_progress; if (unlikely(nolock)) { local_irq_save(flags); diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 43db715f1502..5219738ffd11 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -492,6 +492,23 @@ static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) sysrq_key_table[i] = op_p; } +#ifdef CONFIG_MAGIC_SYSRQ_FORCE_PRINTK + +int sysrq_in_progress; + +static void set_sysrq_in_progress(int value) +{ + sysrq_in_progress = value; +} + +#else + +static void set_sysrq_in_progress(int value) +{ +} + +#endif + void __handle_sysrq(int key, bool check_mask) { struct sysrq_key_op *op_p; @@ -500,6 +517,9 @@ void __handle_sysrq(int key, bool check_mask) unsigned long flags; spin_lock_irqsave(&sysrq_key_table_lock, flags); + + set_sysrq_in_progress(1); + /* * Raise the apparent loglevel to maximum so that the sysrq header * is shown to provide the user with positive feedback. We do not @@ -541,6 +561,9 @@ void __handle_sysrq(int key, bool check_mask) printk("\n"); console_loglevel = orig_log_level; } + + set_sysrq_in_progress(0); + spin_unlock_irqrestore(&sysrq_key_table_lock, flags); } diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h index 7faf933cced7..d224c0bae8df 100644 --- a/include/linux/sysrq.h +++ b/include/linux/sysrq.h @@ -38,6 +38,11 @@ struct sysrq_key_op { int enable_mask; }; +#ifdef CONFIG_MAGIC_SYSRQ_FORCE_PRINTK +extern int sysrq_in_progress; +#else +#define sysrq_in_progress 0 +#endif #ifdef CONFIG_MAGIC_SYSRQ /* Generic SysRq interface -- you may call it from any device driver, supplying diff --git a/kernel/printk.c b/kernel/printk.c index 13ea6a9a7ce6..9eabbbbae463 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -21,6 +21,7 @@ #include <linux/tty.h> #include <linux/tty_driver.h> #include <linux/console.h> +#include <linux/sysrq.h> #include <linux/init.h> #include <linux/jiffies.h> #include <linux/nmi.h> @@ -834,8 +835,8 @@ static int console_trylock_for_printk(unsigned int cpu, unsigned long flags) { int retval = 0, wake = 0; #ifdef CONFIG_PREEMPT_RT_FULL - int lock = !early_boot_irqs_disabled && !irqs_disabled_flags(flags) && - !preempt_count(); + int lock = (!early_boot_irqs_disabled && !irqs_disabled_flags(flags) && + !preempt_count()) || sysrq_in_progress; #else int lock = 1; #endif diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c347db3e08c2..13a937b16bfd 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -62,6 +62,28 @@ config MAGIC_SYSRQ keys are documented in <file:Documentation/sysrq.txt>. Don't say Y unless you really know what this hack does. +config MAGIC_SYSRQ_FORCE_PRINTK + bool "Force printk from Magic SysRq" + depends on MAGIC_SYSRQ && PREEMPT_RT_FULL + default n + help + Allow the output from Magic SysRq to be output immediately, even if + this causes large latencies. This can cause performance problems + for real-time processes. + + If PREEMPT_RT_FULL, printk() will not try to acquire the console lock + when interrupts or preemption are disabled. If the console lock is + not acquired the printk() output will be buffered, but will not be + output immediately. Some drivers call into the Magic SysRq code + with interrupts or preemption disabled, so the output of Magic SysRq + will be buffered instead of printing immediately if this option is + not selected. + + Even with this option selected, Magic SysRq output will be delayed + if the attempt to acquire the console lock fails. + + Don't say Y unless you really know what this hack does. + config STRIP_ASM_SYMS bool "Strip assembler-generated symbols during link" default n |