linux-kernel - [PATCH 1/2] printk: nbcon: move locked_port flag to struct uart

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Message-Id: <20240123054033.183114-2-junxiao.chang@intel.com>
Date: Tue, 23 Jan 2024 13:40:32 +0800
From: Junxiao Chang <junxiao.chang@...el.com>
To: bigeasy@...utronix.de,
	tglx@...utronix.de,
	rostedt@...dmis.org,
	linux-kernel@...r.kernel.org
Cc: john.ogness@...utronix.de,
	hao3.li@...el.com,
	lili.li@...el.com,
	jianfeng.gao@...el.com,
	linux-rt-users@...r.kernel.org
Subject: [PATCH 1/2] printk: nbcon: move locked_port flag to struct uart_port

Console pointer in uart_port might be shared among multiple uart
ports. Flag port locked by nbcon should be saved in uart_port
structure instead of in console structure.

Fixes: 6424f396c49e ("printk: nbcon: Implement processing in port->lock wrapper")
Suggested-by: John Ogness <john.ogness@...utronix.de>
Signed-off-by: Junxiao Chang <junxiao.chang@...el.com>
---
 include/linux/console.h     | 2 --
 include/linux/serial_core.h | 1 +
 kernel/printk/nbcon.c       | 8 ++++----
 3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/include/linux/console.h b/include/linux/console.h
index f8a0628678886..1eb9580e9b18a 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -304,7 +304,6 @@ struct nbcon_write_context {
  * @nbcon_state:	State for nbcon consoles
  * @nbcon_seq:		Sequence number of the next record for nbcon to print
  * @pbufs:		Pointer to nbcon private buffer
- * @locked_port:	True, if the port lock is locked by nbcon
  * @kthread:		Printer kthread for this console
  * @rcuwait:		RCU-safe wait object for @kthread waking
  * @irq_work:		Defer @kthread waking to IRQ work context
@@ -338,7 +337,6 @@ struct console {
 	atomic_t		__private nbcon_state;
 	atomic_long_t		__private nbcon_seq;
 	struct printk_buffers	*pbufs;
-	bool			locked_port;
 	struct task_struct	*kthread;
 	struct rcuwait		rcuwait;
 	struct irq_work		irq_work;
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 245c11753effd..b2221a50fcb29 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -488,6 +488,7 @@ struct uart_port {
 	struct uart_icount	icount;			/* statistics */
 
 	struct console		*cons;			/* struct console, if any */
+	bool			nbcon_locked_port;	/* True, if the port is locked by nbcon */
 	/* flags must be updated while holding port mutex */
 	upf_t			flags;
 
diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
index 1b1b585b1675b..b53d93585ee71 100644
--- a/kernel/printk/nbcon.c
+++ b/kernel/printk/nbcon.c
@@ -1586,7 +1586,7 @@ void nbcon_acquire(struct uart_port *up)
 	if (!uart_is_nbcon(up))
 		return;
 
-	WARN_ON_ONCE(con->locked_port);
+	WARN_ON_ONCE(up->nbcon_locked_port);
 
 	do {
 		do {
@@ -1597,7 +1597,7 @@ void nbcon_acquire(struct uart_port *up)
 
 	} while (!nbcon_context_enter_unsafe(&ctxt));
 
-	con->locked_port = true;
+	up->nbcon_locked_port = true;
 }
 EXPORT_SYMBOL_GPL(nbcon_acquire);
 
@@ -1623,13 +1623,13 @@ void nbcon_release(struct uart_port *up)
 		.prio		= NBCON_PRIO_NORMAL,
 	};
 
-	if (!con->locked_port)
+	if (!up->nbcon_locked_port)
 		return;
 
 	if (nbcon_context_exit_unsafe(&ctxt))
 		nbcon_context_release(&ctxt);
 
-	con->locked_port = false;
+	up->nbcon_locked_port = false;
 }
 EXPORT_SYMBOL_GPL(nbcon_release);
 
-- 
2.34.1