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Message-ID: <4FB44EF1.9050809@am.sony.com>
Date: Wed, 16 May 2012 18:05:53 -0700
From: Frank Rowand <frank.rowand@...sony.com>
To: <tglx@...utronix.de>, <linux-kernel@...r.kernel.org>,
"linux-rt-users@...r.kernel.org" <linux-rt-users@...r.kernel.org>
Subject: [PATCH RT 1/2] fix printk flush of messages
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@...sony.com>
---
drivers/tty/serial/cpm_uart/cpm_uart_core.c | 2 1 + 1 - 0 !
drivers/tty/sysrq.c | 23 0 + 23 - 0 !
include/linux/sysrq.h | 5 0 + 5 - 0 !
kernel/printk.c | 5 2 + 3 - 0 !
lib/Kconfig.debug | 22 0 + 22 - 0 !
5 files changed, 3 insertions(+), 54 deletions(-)
Index: b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
===================================================================
--- 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(struc
{
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);
Index: b/drivers/tty/sysrq.c
===================================================================
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -495,23 +495,6 @@ static void __sysrq_put_key_op(int key,
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;
@@ -520,9 +503,6 @@ void __handle_sysrq(int key, bool check_
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
@@ -564,9 +544,6 @@ void __handle_sysrq(int key, bool check_
printk("\n");
console_loglevel = orig_log_level;
}
-
- set_sysrq_in_progress(0);
-
spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
}
Index: b/include/linux/sysrq.h
===================================================================
--- 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
Index: b/kernel/printk.c
===================================================================
--- 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>
@@ -847,8 +846,8 @@ static int console_trylock_for_printk(un
{
int retval = 0, wake = 0;
#ifdef CONFIG_PREEMPT_RT_FULL
- int lock = (!early_boot_irqs_disabled && !irqs_disabled_flags(flags) &&
- !preempt_count()) || sysrq_in_progress;
+ int lock = !early_boot_irqs_disabled && !irqs_disabled_flags(flags) &&
+ !preempt_count();
#else
int lock = 1;
#endif
Index: b/lib/Kconfig.debug
===================================================================
--- 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
--
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