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Subject[PATCH RT 1/2] fix printk flush of messages
From: Frank Rowand <frank.rowand@am.sony.com>

Reverse preempt-rt-allow-immediate-magic-sysrq-output-for-preempt_rt_full.patch

The problem addressed by that patch does not exist after applying
console-make-rt-friendly-update.patch

Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
Link: http://lkml.kernel.org/r/4FB44EF1.9050809@am.sony.com
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
drivers/tty/serial/cpm_uart/cpm_uart_core.c | 2 +-
drivers/tty/sysrq.c | 23 -----------------------
include/linux/sysrq.h | 5 -----
kernel/printk.c | 5 ++---
lib/Kconfig.debug | 22 ----------------------
5 files changed, 3 insertions(+), 54 deletions(-)

diff --git a/drivers/tty/serial/cpm_uart/cpm_uart_core.c b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
index 2a75c84..9488da7 100644
--- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
@@ -1225,7 +1225,7 @@ 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 || sysrq_in_progress;
+ int nolock = oops_in_progress;

if (unlikely(nolock)) {
local_irq_save(flags);
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 5219738..43db715 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -492,23 +492,6 @@ 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;
@@ -517,9 +500,6 @@ 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
@@ -561,9 +541,6 @@ 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 d224c0b..7faf933 100644
--- a/include/linux/sysrq.h
+++ b/include/linux/sysrq.h
@@ -38,11 +38,6 @@ 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 f2c459f..ea71fae 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -21,7 +21,6 @@
#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 +833,8 @@ static int console_trylock_for_printk(unsigned int cpu, unsigned long flags)
__releases(&logbuf_lock)
{
#ifdef CONFIG_PREEMPT_RT_FULL
- int lock = (!early_boot_irqs_disabled && !irqs_disabled_flags(flags) &&
- (preempt_count() <= 1)) || sysrq_in_progress;
+ int lock = !early_boot_irqs_disabled && !irqs_disabled_flags(flags) &&
+ (preempt_count() <= 1);
#else
int lock = 1;
#endif
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 383b565..1685473 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -62,28 +62,6 @@ 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
--
1.7.10.4



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