[PATCH AUTOSEL 5.15 1/2] printk: Consolidate console deferred printing

[PATCH AUTOSEL 5.15 1/2] printk: Consolidate console deferred printing

[Sasha Levin]

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

[ Upstream commit 696ffaf50e1f8dbc66223ff614473f945f5fb8d8 ]

Printing to consoles can be deferred for several reasons:

- explicitly with printk_deferred()
- printk() in NMI context
- recursive printk() calls

The current implementation is not consistent. For printk_deferred(),
irq work is scheduled twice. For NMI und recursive, panic CPU
suppression and caller delays are not properly enforced.

Correct these inconsistencies by consolidating the deferred printing
code so that vprintk_deferred() is the top-level function for
deferred printing and vprintk_emit() will perform whichever irq_work
queueing is appropriate.

Also add kerneldoc for wake_up_klogd() and defer_console_output() to
clarify their differences and appropriate usage.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230717194607.145135-6-john.ogness@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/printk/printk.c      | 35 ++++++++++++++++++++++++++++-------
 kernel/printk/printk_safe.c |  9 ++-------
 2 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 8d856b7c2e5af..8b110b245d92c 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2269,7 +2269,11 @@ asmlinkage int vprintk_emit(int facility, int level,
 		preempt_enable();
 	}
 
-	wake_up_klogd();
+	if (in_sched)
+		defer_console_output();
+	else
+		wake_up_klogd();
+
 	return printed_len;
 }
 EXPORT_SYMBOL(vprintk_emit);
@@ -3277,11 +3281,33 @@ static void __wake_up_klogd(int val)
 	preempt_enable();
 }
 
+/**
+ * wake_up_klogd - Wake kernel logging daemon
+ *
+ * Use this function when new records have been added to the ringbuffer
+ * and the console printing of those records has already occurred or is
+ * known to be handled by some other context. This function will only
+ * wake the logging daemon.
+ *
+ * Context: Any context.
+ */
 void wake_up_klogd(void)
 {
 	__wake_up_klogd(PRINTK_PENDING_WAKEUP);
 }
 
+/**
+ * defer_console_output - Wake kernel logging daemon and trigger
+ *	console printing in a deferred context
+ *
+ * Use this function when new records have been added to the ringbuffer,
+ * this context is responsible for console printing those records, but
+ * the current context is not allowed to perform the console printing.
+ * Trigger an irq_work context to perform the console printing. This
+ * function also wakes the logging daemon.
+ *
+ * Context: Any context.
+ */
 void defer_console_output(void)
 {
 	/*
@@ -3298,12 +3324,7 @@ void printk_trigger_flush(void)
 
 int vprintk_deferred(const char *fmt, va_list args)
 {
-	int r;
-
-	r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, fmt, args);
-	defer_console_output();
-
-	return r;
+	return vprintk_emit(0, LOGLEVEL_SCHED, NULL, fmt, args);
 }
 
 int _printk_deferred(const char *fmt, ...)
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index ef0f9a2044da1..6d10927a07d83 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -38,13 +38,8 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 	 * Use the main logbuf even in NMI. But avoid calling console
 	 * drivers that might have their own locks.
 	 */
-	if (this_cpu_read(printk_context) || in_nmi()) {
-		int len;
-
-		len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
-		defer_console_output();
-		return len;
-	}
+	if (this_cpu_read(printk_context) || in_nmi())
+		return vprintk_deferred(fmt, args);
 
 	/* No obstacles. */
 	return vprintk_default(fmt, args);
-- 
2.40.1

[PATCH AUTOSEL 5.15 2/2] thermal/drivers/sun8i: Free calibration nvmem after reading it

[Sasha Levin]

From: Mark Brown <broonie@kernel.org>

[ Upstream commit c51592a95f360aabf2b8a5691c550e1749dc41eb ]

The sun8i thermal driver reads calibration data via the nvmem API at
startup, updating the device configuration and not referencing the data
again.  Rather than explicitly freeing the nvmem data the driver relies
on devm_ to release it, even though the data is never referenced again.
The allocation is still tracked so it's not leaked but this is notable
when looking at the code and is a little wasteful so let's instead
explicitly free the nvmem after we're done with it.

Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20230719-thermal-sun8i-free-nvmem-v1-1-f553d5afef79@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/thermal/sun8i_thermal.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/sun8i_thermal.c b/drivers/thermal/sun8i_thermal.c
index cd464db064142..c1650b20e4975 100644
--- a/drivers/thermal/sun8i_thermal.c
+++ b/drivers/thermal/sun8i_thermal.c
@@ -286,7 +286,7 @@ static int sun8i_ths_calibrate(struct ths_device *tmdev)
 	size_t callen;
 	int ret = 0;
 
-	calcell = devm_nvmem_cell_get(dev, "calibration");
+	calcell = nvmem_cell_get(dev, "calibration");
 	if (IS_ERR(calcell)) {
 		if (PTR_ERR(calcell) == -EPROBE_DEFER)
 			return -EPROBE_DEFER;
@@ -316,6 +316,8 @@ static int sun8i_ths_calibrate(struct ths_device *tmdev)
 
 	kfree(caldata);
 out:
+	if (!IS_ERR(calcell))
+		nvmem_cell_put(calcell);
 	return ret;
 }
 
-- 
2.40.1