[linux-yocto] [PATCH 2/2] printk: An all-in-one commit to fix build failures

[Hongzhi.Song]

From: John Ogness <john.ogness at linutronix.de>

This commit contains addresses several build failures which were
reported by the kbuild test robot.
The fixes were folded into the original commits.

Reported-by: kbuild test robot <lkp at intel.com>
Signed-off-by: John Ogness <john.ogness at linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy at linutronix.de>

Backport the commit from linux-v5.0.5-rt3 to to fix the following
build error for powerpc:
[https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/commit/?h=linux-5.0.y-rt&id=bb54b39acf40a4fe4c112127e0a1497b9f6072b7]

error: implicit declaration of function 'printk_safe_flush_on_panic'

Signed-off-by: Hongzhi.Song <hongzhi.song at windriver.com>
---
 arch/powerpc/kernel/traps.c    |  1 -
 arch/powerpc/kernel/watchdog.c |  5 -----
 kernel/printk/printk.c         | 16 ++++++++++++++--
 lib/printk_ringbuffer.c        |  8 +++++++-
 4 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 64936b6..955a7c1 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -174,7 +174,6 @@ extern void panic_flush_kmsg_start(void)
 
 extern void panic_flush_kmsg_end(void)
 {
-	printk_safe_flush_on_panic();
 	kmsg_dump(KMSG_DUMP_PANIC);
 	bust_spinlocks(0);
 	debug_locks_off();
diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index 3c6ab22..bf98181 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -181,11 +181,6 @@ static void watchdog_smp_panic(int cpu, u64 tb)
 
 	wd_smp_unlock(&flags);
 
-	printk_safe_flush();
-	/*
-	 * printk_safe_flush() seems to require another print
-	 * before anything actually goes out to console.
-	 */
 	if (sysctl_hardlockup_all_cpu_backtrace)
 		trigger_allbutself_cpu_backtrace();
 
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 5cfd8ea..997d07b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -370,6 +370,18 @@ static u64 clear_seq;
 #define LOG_LEVEL(v)		((v) & 0x07)
 #define LOG_FACILITY(v)		((v) >> 3 & 0xff)
 
+/* Return log buffer address */
+char *log_buf_addr_get(void)
+{
+	return printk_rb.buffer;
+}
+
+/* Return log buffer size */
+u32 log_buf_len_get(void)
+{
+	return (1 << printk_rb.size_bits);
+}
+
 /* human readable text of the record */
 static char *log_text(const struct printk_log *msg)
 {
@@ -1910,7 +1922,7 @@ asmlinkage int vprintk_emit(int facility, int level,
 }
 EXPORT_SYMBOL(vprintk_emit);
 
-__printf(1, 0) int vprintk_func(const char *fmt, va_list args)
+static __printf(1, 0) int vprintk_func(const char *fmt, va_list args)
 {
 	return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
 }
@@ -2684,7 +2696,7 @@ static int __init init_printk_kthread(void)
 }
 late_initcall(init_printk_kthread);
 
-int vprintk_deferred(const char *fmt, va_list args)
+static int vprintk_deferred(const char *fmt, va_list args)
 {
 	return vprintk_emit(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
 }
diff --git a/lib/printk_ringbuffer.c b/lib/printk_ringbuffer.c
index ce33b5a..9a31d7d 100644
--- a/lib/printk_ringbuffer.c
+++ b/lib/printk_ringbuffer.c
@@ -196,8 +196,14 @@ void prb_commit(struct prb_handle *h)
 
 	if (changed) {
 		atomic_long_inc(&rb->wq_counter);
-		if (wq_has_sleeper(rb->wq))
+		if (wq_has_sleeper(rb->wq)) {
+#ifdef CONFIG_IRQ_WORK
 			irq_work_queue(rb->wq_work);
+#else
+			if (!in_nmi())
+				wake_up_interruptible_all(rb->wq);
+#endif
+		}
 	}
 }
 
-- 
2.8.1