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Subject[RFC PATCH v1 25/25] printk: remove unused code
Date
Code relating to the safe context and anything dealing with the
previous log buffer implementation is no longer in use. Remove it.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
kernel/printk/internal.h | 53 ---------------
kernel/printk/printk.c | 167 ++++-------------------------------------------
lib/bust_spinlocks.c | 3 +-
3 files changed, 13 insertions(+), 210 deletions(-)
delete mode 100644 kernel/printk/internal.h

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
deleted file mode 100644
index 59ad43dba837..000000000000
--- a/kernel/printk/internal.h
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- * internal.h - printk internal definitions
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, see <http://www.gnu.org/licenses/>.
- */
-#include <linux/percpu.h>
-
-#ifdef CONFIG_PRINTK
-
-#define PRINTK_SAFE_CONTEXT_MASK 0x3fffffff
-#define PRINTK_NMI_DIRECT_CONTEXT_MASK 0x40000000
-#define PRINTK_NMI_CONTEXT_MASK 0x80000000
-
-extern raw_spinlock_t logbuf_lock;
-
-__printf(5, 0)
-int vprintk_store(int facility, int level,
- const char *dict, size_t dictlen,
- const char *fmt, va_list args);
-
-__printf(1, 0) int vprintk_default(const char *fmt, va_list args);
-__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
-__printf(1, 0) int vprintk_func(const char *fmt, va_list args);
-
-void defer_console_output(void);
-
-#else
-
-__printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return 0; }
-
-/*
- * In !PRINTK builds we still export logbuf_lock spin_lock, console_sem
- * semaphore and some of console functions (console_unlock()/etc.), so
- * printk-safe must preserve the existing local IRQ guarantees.
- */
-#endif /* CONFIG_PRINTK */
-
-#define printk_safe_enter_irqsave(flags) local_irq_save(flags)
-#define printk_safe_exit_irqrestore(flags) local_irq_restore(flags)
-
-#define printk_safe_enter_irq() local_irq_disable()
-#define printk_safe_exit_irq() local_irq_enable()
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 6d5bb7f5f584..8ef35c398887 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -60,7 +60,6 @@

#include "console_cmdline.h"
#include "braille.h"
-#include "internal.h"

int console_printk[5] = {
CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */
@@ -346,41 +345,6 @@ __packed __aligned(4)
#endif
;

-/*
- * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken
- * within the scheduler's rq lock. It must be released before calling
- * console_unlock() or anything else that might wake up a process.
- */
-DEFINE_RAW_SPINLOCK(logbuf_lock);
-
-/*
- * Helper macros to lock/unlock logbuf_lock and switch between
- * printk-safe/unsafe modes.
- */
-#define logbuf_lock_irq() \
- do { \
- printk_safe_enter_irq(); \
- raw_spin_lock(&logbuf_lock); \
- } while (0)
-
-#define logbuf_unlock_irq() \
- do { \
- raw_spin_unlock(&logbuf_lock); \
- printk_safe_exit_irq(); \
- } while (0)
-
-#define logbuf_lock_irqsave(flags) \
- do { \
- printk_safe_enter_irqsave(flags); \
- raw_spin_lock(&logbuf_lock); \
- } while (0)
-
-#define logbuf_unlock_irqrestore(flags) \
- do { \
- raw_spin_unlock(&logbuf_lock); \
- printk_safe_exit_irqrestore(flags); \
- } while (0)
-
DECLARE_STATIC_PRINTKRB_CPULOCK(printk_cpulock);

#ifdef CONFIG_PRINTK
@@ -390,23 +354,15 @@ DECLARE_STATIC_PRINTKRB(printk_rb, CONFIG_LOG_BUF_SHIFT, &printk_cpulock);
static DEFINE_MUTEX(syslog_lock);
DECLARE_STATIC_PRINTKRB_ITER(syslog_iter, &printk_rb);

-DECLARE_WAIT_QUEUE_HEAD(log_wait);
-/* the next printk record to read by syslog(READ) or /proc/kmsg */
+/* the last printk record read by syslog(READ) or /proc/kmsg */
static u64 syslog_seq;
static size_t syslog_partial;
static bool syslog_time;

-/* index and sequence number of the first record stored in the buffer */
-static u32 log_first_idx;
-
-/* index and sequence number of the next record to store in the buffer */
-static u32 log_next_idx;
-
static DEFINE_MUTEX(kmsg_dump_lock);

-/* the next printk record to read after the last 'clear' command */
+/* the last printk record at the last 'clear' command */
static u64 clear_seq;
-static u32 clear_idx;

#define PREFIX_MAX 32
#define LOG_LINE_MAX (1024 - PREFIX_MAX)
@@ -414,26 +370,6 @@ static u32 clear_idx;
#define LOG_LEVEL(v) ((v) & 0x07)
#define LOG_FACILITY(v) ((v) >> 3 & 0xff)

-/* record buffer */
-#define LOG_ALIGN __alignof__(struct printk_log)
-#define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT)
-#define LOG_BUF_LEN_MAX (u32)(1 << 31)
-static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
-static char *log_buf = __log_buf;
-static u32 log_buf_len = __LOG_BUF_LEN;
-
-/* Return log buffer address */
-char *log_buf_addr_get(void)
-{
- return log_buf;
-}
-
-/* Return log buffer size */
-u32 log_buf_len_get(void)
-{
- return log_buf_len;
-}
-
/* human readable text of the record */
static char *log_text(const struct printk_log *msg)
{
@@ -944,11 +880,6 @@ const struct file_operations kmsg_fops = {
*/
void log_buf_vmcoreinfo_setup(void)
{
- VMCOREINFO_SYMBOL(log_buf);
- VMCOREINFO_SYMBOL(log_buf_len);
- VMCOREINFO_SYMBOL(log_first_idx);
- VMCOREINFO_SYMBOL(clear_idx);
- VMCOREINFO_SYMBOL(log_next_idx);
/*
* Export struct printk_log size and field offsets. User space tools can
* parse it and detect any changes to structure down the line.
@@ -961,6 +892,8 @@ void log_buf_vmcoreinfo_setup(void)
}
#endif

+/* FIXME: no support for buffer resizing */
+#if 0
/* requested log_buf_len from kernel cmdline */
static unsigned long __initdata new_log_buf_len;

@@ -1026,9 +959,12 @@ static void __init log_buf_add_cpu(void)
#else /* !CONFIG_SMP */
static inline void log_buf_add_cpu(void) {}
#endif /* CONFIG_SMP */
+#endif /* 0 */

void __init setup_log_buf(int early)
{
+/* FIXME: no support for buffer resizing */
+#if 0
unsigned long flags;
char *new_log_buf;
unsigned int free;
@@ -1067,6 +1003,7 @@ void __init setup_log_buf(int early)
pr_info("log_buf_len: %u bytes\n", log_buf_len);
pr_info("early log buf free: %u(%u%%)\n",
free, (free * 100) / __LOG_BUF_LEN);
+#endif
}

static bool __read_mostly ignore_loglevel;
@@ -2023,31 +1960,6 @@ asmlinkage __visible int printk(const char *fmt, ...)
return r;
}
EXPORT_SYMBOL(printk);
-
-#else /* CONFIG_PRINTK */
-
-#define LOG_LINE_MAX 0
-#define PREFIX_MAX 0
-#define printk_time false
-
-static u64 syslog_seq;
-static u32 log_first_idx;
-static char *log_text(const struct printk_log *msg) { return NULL; }
-static char *log_dict(const struct printk_log *msg) { return NULL; }
-static struct printk_log *log_from_idx(u32 idx) { return NULL; }
-static u32 log_next(u32 idx) { return 0; }
-static ssize_t msg_print_ext_header(char *buf, size_t size,
- struct printk_log *msg,
- u64 seq) { return 0; }
-static ssize_t msg_print_ext_body(char *buf, size_t size,
- char *dict, size_t dict_len,
- char *text, size_t text_len) { return 0; }
-static void call_console_drivers(u64 seq, const char *ext_text, size_t ext_len,
- const char *text, size_t len, int level) {}
-static size_t msg_print_text(const struct printk_log *msg, bool syslog,
- bool time, char *buf, size_t size) { return 0; }
-static bool suppress_message_printing(int level) { return false; }
-
#endif /* CONFIG_PRINTK */

#ifdef CONFIG_EARLY_PRINTK
@@ -2343,15 +2255,10 @@ void console_unblank(void)
void console_flush_on_panic(void)
{
/*
- * If someone else is holding the console lock, trylock will fail
- * and may_schedule may be set. Ignore and proceed to unlock so
- * that messages are flushed out. As this can be called from any
- * context and we don't want to get preempted while flushing,
- * ensure may_schedule is cleared.
+ * FIXME: This is currently a NOP. Emergency messages will have been
+ * printed, but what about if write_atomic is not available on the
+ * console? What if the printk kthread is still alive?
*/
- console_trylock();
- console_may_schedule = 0;
- console_unlock();
}

/*
@@ -2700,43 +2607,6 @@ 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_PENDING_WAKEUP 0x01
-#define PRINTK_PENDING_OUTPUT 0x02
-
-static DEFINE_PER_CPU(int, printk_pending);
-
-static void wake_up_klogd_work_func(struct irq_work *irq_work)
-{
- int pending = __this_cpu_xchg(printk_pending, 0);
-
- if (pending & PRINTK_PENDING_OUTPUT) {
- /* If trylock fails, someone else is doing the printing */
- if (console_trylock())
- console_unlock();
- }
-
- 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(this_cpu_ptr(&wake_up_klogd_work));
- }
- preempt_enable();
-}
-
static int printk_kthread_func(void *data)
{
struct prb_iterator iter;
@@ -2802,22 +2672,9 @@ static int __init init_printk_kthread(void)
}
late_initcall(init_printk_kthread);

-void defer_console_output(void)
-{
- preempt_disable();
- __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
- irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
- preempt_enable();
-}
-
int vprintk_deferred(const char *fmt, va_list args)
{
- int r;
-
- r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args);
- defer_console_output();
-
- return r;
+ return vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args);
}

int printk_deferred(const char *fmt, ...)
diff --git a/lib/bust_spinlocks.c b/lib/bust_spinlocks.c
index 8be59f84eaea..c6e083323d1b 100644
--- a/lib/bust_spinlocks.c
+++ b/lib/bust_spinlocks.c
@@ -26,7 +26,6 @@ void bust_spinlocks(int yes)
unblank_screen();
#endif
console_unblank();
- if (--oops_in_progress == 0)
- wake_up_klogd();
+ --oops_in_progress;
}
}
--
2.11.0
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