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Date: Thu, 14 Mar 2013 15:26:29 +0100
From: Frederic Weisbecker <fweisbec@...il.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Frederic Weisbecker <fweisbec@...il.com>,
James Hogan <james.hogan@...tec.com>,
Steven Rostedt <rostedt@...dmis.org>,
Peter Zijlstra <peterz@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 2/2] printk: Provide a wake_up_klogd() off-case
wake_up_klogd() is useless when CONFIG_PRINTK=n because
neither printk() nor printk_sched() are in use and there
are actually no waiter on log_wait waitqueue. It should
be a stub in this case for users like bust_spinlocks().
Otherwise this results in this warning when CONFIG_PRINTK=n
and CONFIG_IRQ_WORK=n:
kernel/built-in.o In function `wake_up_klogd':
(.text.wake_up_klogd+0xb4): undefined reference to `irq_work_queue'
To fix this, provide an off-case for wake_up_klogd() when
CONFIG_PRINTK=n.
There is much more from console_unlock() and other console
related code in printk.c that should be moved under
CONFIG_PRINTK. But for now, focus on a minimal fix as we passed
the merged window already.
Reported-by: James Hogan <james.hogan@...tec.com>
Cc: James Hogan <james.hogan@...tec.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
include/linux/kernel.h | 1 -
include/linux/printk.h | 6 +++
kernel/printk.c | 80 +++++++++++++++++++++++------------------------
3 files changed, 45 insertions(+), 42 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 80d3687..79fdd80 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -390,7 +390,6 @@ extern struct pid *session_of_pgrp(struct pid *pgrp);
unsigned long int_sqrt(unsigned long);
extern void bust_spinlocks(int yes);
-extern void wake_up_klogd(void);
extern int oops_in_progress; /* If set, an oops, panic(), BUG() or die() is in progress */
extern int panic_timeout;
extern int panic_on_oops;
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 1249a54..822171f 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -134,6 +134,8 @@ extern int printk_delay_msec;
extern int dmesg_restrict;
extern int kptr_restrict;
+extern void wake_up_klogd(void);
+
void log_buf_kexec_setup(void);
void __init setup_log_buf(int early);
#else
@@ -162,6 +164,10 @@ static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies,
return false;
}
+static inline void wake_up_klogd(void)
+{
+}
+
static inline void log_buf_kexec_setup(void)
{
}
diff --git a/kernel/printk.c b/kernel/printk.c
index 0b31715..abbdd9e 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -63,8 +63,6 @@ void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
-DECLARE_WAIT_QUEUE_HEAD(log_wait);
-
int console_printk[4] = {
DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
@@ -224,6 +222,7 @@ struct log {
static DEFINE_RAW_SPINLOCK(logbuf_lock);
#ifdef CONFIG_PRINTK
+DECLARE_WAIT_QUEUE_HEAD(log_wait);
/* the next printk record to read by syslog(READ) or /proc/kmsg */
static u64 syslog_seq;
static u32 syslog_idx;
@@ -1957,45 +1956,6 @@ int is_console_locked(void)
return console_locked;
}
-/*
- * Delayed printk version, for scheduler-internal messages:
- */
-#define PRINTK_BUF_SIZE 512
-
-#define PRINTK_PENDING_WAKEUP 0x01
-#define PRINTK_PENDING_SCHED 0x02
-
-static DEFINE_PER_CPU(int, printk_pending);
-static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
-
-static void wake_up_klogd_work_func(struct irq_work *irq_work)
-{
- int pending = __this_cpu_xchg(printk_pending, 0);
-
- if (pending & PRINTK_PENDING_SCHED) {
- char *buf = __get_cpu_var(printk_sched_buf);
- printk(KERN_WARNING "[sched_delayed] %s", buf);
- }
-
- if (pending & PRINTK_PENDING_WAKEUP)
- wake_up_interruptible(&log_wait);
-}
-
-static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
- .func = wake_up_klogd_work_func,
- .flags = IRQ_WORK_LAZY,
-};
-
-void wake_up_klogd(void)
-{
- preempt_disable();
- if (waitqueue_active(&log_wait)) {
- this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
- irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
- }
- preempt_enable();
-}
-
static void console_cont_flush(char *text, size_t size)
{
unsigned long flags;
@@ -2458,6 +2418,44 @@ static int __init printk_late_init(void)
late_initcall(printk_late_init);
#if defined CONFIG_PRINTK
+/*
+ * Delayed printk version, for scheduler-internal messages:
+ */
+#define PRINTK_BUF_SIZE 512
+
+#define PRINTK_PENDING_WAKEUP 0x01
+#define PRINTK_PENDING_SCHED 0x02
+
+static DEFINE_PER_CPU(int, printk_pending);
+static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
+
+static void wake_up_klogd_work_func(struct irq_work *irq_work)
+{
+ int pending = __this_cpu_xchg(printk_pending, 0);
+
+ if (pending & PRINTK_PENDING_SCHED) {
+ char *buf = __get_cpu_var(printk_sched_buf);
+ printk(KERN_WARNING "[sched_delayed] %s", buf);
+ }
+
+ if (pending & PRINTK_PENDING_WAKEUP)
+ wake_up_interruptible(&log_wait);
+}
+
+static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
+ .func = wake_up_klogd_work_func,
+ .flags = IRQ_WORK_LAZY,
+};
+
+void wake_up_klogd(void)
+{
+ preempt_disable();
+ if (waitqueue_active(&log_wait)) {
+ this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
+ irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
+ }
+ preempt_enable();
+}
int printk_sched(const char *fmt, ...)
{
--
1.7.5.4
--
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