From patchwork Sun Aug 4 00:51:13 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Ogness X-Patchwork-Id: 816718 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AC192B673; Sun, 4 Aug 2024 00:51:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722732713; cv=none; b=iKQ8dL6Ogh064QE3/Vjv47pqCYLVBX9/C9lwqIaPc7+acxq6EoswOOx0Lqau1IfkT5fLkzx+2eKLz7x+p6Mk+n3NLUnJnYel2L6izceYLpYN7E50WmGlxv7J0avkEht98sy8ADvmlApdhGuPgkKfkP80XNWNWpEztUxrV/8v2Gw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722732713; c=relaxed/simple; bh=i7g9Rk6E1rRqftOtHZzjKlxcVFM+YP6E/P/94xSlZdE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=WFnmpDorX0pqKr7CKin1CWm8K4XawszJ6WKifxaWv8C/O/2yoL3r7MCRZznioCLIz2pHj5nZ/uAdX4P8lbbCI+mga1W/mJptqkz8fkBrNkaL2v3EMx2EqHvWyQT6Xom50TF0k7nPzUJIKTesRvF3d3qujv60HWrmKTOwXEWkABk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=iFutFd+n; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=SBE5EMqj; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="iFutFd+n"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="SBE5EMqj" From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1722732704; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EwPBydyTGTYXegM2JVbnpVHJON//wTjw/xvV7q8bAP0=; b=iFutFd+nbFnB13SQ9hIqx4evQV3KuPsbFZrZfQj0rSBNxSr0adh4NRrPSHbTRuLjNRBU4n bGa0pU2JCzxzlMMqqHOvtdshDf05EzUgG+8t1Sd0gMI/m9TI5eyILXqQIjiHgFy6Dh/G2/ dEFqu2+gtSSQxi6kyjVz8512VzhdHyjX6IkYS/VeZtOumHWGoqS0fOL+1QHw+iKj0DwSbz t2Jpv+bslMfpOVzT9fgHSnOfgdPiDP48M/iI1a+lXU4adfTEQom6gncWaFGeBDbbMCf9ND i0jbbY1IEcUmvJv2eSGKQY888apUuKoBSbhx/UNlp0fmxINM8JZoipcQ6ADFLg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1722732704; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EwPBydyTGTYXegM2JVbnpVHJON//wTjw/xvV7q8bAP0=; b=SBE5EMqjeqcj2iTPMMaONIt+erFukqHHiehMt+23DxJToxZWAiKjamvhCzEEAw8tRiPo63 KdVZe0XST2lXL5Bg== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org Subject: [PATCH printk v7 10/35] serial: core: Provide low-level functions to lock port Date: Sun, 4 Aug 2024 02:57:13 +0206 Message-Id: <20240804005138.3722656-11-john.ogness@linutronix.de> In-Reply-To: <20240804005138.3722656-1-john.ogness@linutronix.de> References: <20240804005138.3722656-1-john.ogness@linutronix.de> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 It will be necessary at times for the uart nbcon console drivers to acquire the port lock directly (without the additional nbcon functionality of the port lock wrappers). These are special cases such as the implementation of the device_lock()/device_unlock() callbacks or for internal port lock wrapper synchronization. Provide low-level variants __uart_port_lock_irqsave() and __uart_port_unlock_irqrestore() for this purpose. Signed-off-by: John Ogness Reviewed-by: Petr Mladek Acked-by: Greg Kroah-Hartman --- include/linux/serial_core.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index aea25eef9a1a..8872cd21e70a 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -590,6 +590,24 @@ struct uart_port { void *private_data; /* generic platform data pointer */ }; +/* + * Only for console->device_lock()/_unlock() callbacks and internal + * port lock wrapper synchronization. + */ +static inline void __uart_port_lock_irqsave(struct uart_port *up, unsigned long *flags) +{ + spin_lock_irqsave(&up->lock, *flags); +} + +/* + * Only for console->device_lock()/_unlock() callbacks and internal + * port lock wrapper synchronization. + */ +static inline void __uart_port_unlock_irqrestore(struct uart_port *up, unsigned long flags) +{ + spin_unlock_irqrestore(&up->lock, flags); +} + /** * uart_port_lock - Lock the UART port * @up: Pointer to UART port structure From patchwork Sun Aug 4 00:51:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Ogness X-Patchwork-Id: 816717 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6B51F101F7; Sun, 4 Aug 2024 00:51:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722732715; cv=none; b=TslB5ML/WtKwAEkxV+8LCXomE+vMH6bYRCr9USOHlT+GOvkElHoHU98Kt2l0ApY3XKWefDt7raGhT5722Ci+LdEURE1U50FA5GG7tcXnGNf0WE797fRQ3mpVRoQ3HA8Ht3KpTYyEGPqTb7Z3pLBmUYuLnd+tZo9gIIpUm8L8Q7o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722732715; c=relaxed/simple; bh=R4TOefOxndRBCPUXtpdDEsXMvKoXT/g+AiM/wcdCOiI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=rYIwxX2Vo1cUd8SVjf2eR9ytMxSeR7SrdSbmBwW8ZcUIKgwuDSL1mYkmMhhoTYjorOg70vwSjuTWwQ+o07LDpkJHRWceDxmB5U6FBDgric0nD0qsD80vh/uwPEZ65WxL0rmhJBaBhXwXuDQGuvaX+oBMcDi+244NTg6E0gX2LuE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=l/fXZS+x; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=dv56lOLv; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="l/fXZS+x"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="dv56lOLv" From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1722732706; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ElxI59csI9kczE5ClB/S01RcILMnwACUfY2TZOkMQ4U=; b=l/fXZS+x0lNZdVdNF3mHafrcm28dLMexDUad/up+cz844KzgH63zSE6hJuDJrvCGszuSsN VRNUu9HYhxKaDGg+NfOniOXuDuPpQzeoYU3gUiF5mwkdzSJVE9Hd6zyRpQ3jotctYefglB WcX+1xAH6Csh6CqIsNUVuXsdiXfY8R8lvEc/+CIbXtj8BRwYQ6R8n9PbB7RYQUYAhVr3io pb+P12zdxhOW8fNwhlLt/s978Gi3GTj3d4a5n0zoIwXaP0Ptx+ITelip1P0s6/3UtASiaH zbGUam3BqCPHU1ul6uL+rRJSBFnC2+wsAmXtr2BmQ/EAX5b00OMJsRZquTqyYQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1722732706; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ElxI59csI9kczE5ClB/S01RcILMnwACUfY2TZOkMQ4U=; b=dv56lOLvq0mQUvKTp9eZ0uGVOjGWIr1SLxu8RmgIkfxkfSmG3mC7Lm/3+X/odBARzrpDqB YTNN12tEI1Fw5OCQ== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org Subject: [PATCH printk v7 14/35] serial: core: Acquire nbcon context in port->lock wrapper Date: Sun, 4 Aug 2024 02:57:17 +0206 Message-Id: <20240804005138.3722656-15-john.ogness@linutronix.de> In-Reply-To: <20240804005138.3722656-1-john.ogness@linutronix.de> References: <20240804005138.3722656-1-john.ogness@linutronix.de> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Currently the port->lock wrappers uart_port_lock(), uart_port_unlock() (and their variants) only lock/unlock the spin_lock. If the port is an nbcon console that has implemented the write_atomic() callback, the wrappers must also acquire/release the console context and mark the region as unsafe. This allows general port->lock synchronization to be synchronized against the nbcon write_atomic() callback. Note that __uart_port_using_nbcon() relies on the port->lock being held while a console is added and removed from the console list (i.e. all uart nbcon drivers *must* take the port->lock in their device_lock() callbacks). Signed-off-by: John Ogness Acked-by: Greg Kroah-Hartman Reviewed-by: Petr Mladek --- include/linux/serial_core.h | 82 ++++++++++++++++++++++++++++++++++++- 1 file changed, 80 insertions(+), 2 deletions(-) diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 2cf03ff2056a..4ab65874a850 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -11,6 +11,8 @@ #include #include #include +#include +#include #include #include #include @@ -625,6 +627,60 @@ static inline void uart_port_set_cons(struct uart_port *up, struct console *con) up->cons = con; __uart_port_unlock_irqrestore(up, flags); } + +/* Only for internal port lock wrapper usage. */ +static inline bool __uart_port_using_nbcon(struct uart_port *up) +{ + lockdep_assert_held_once(&up->lock); + + if (likely(!uart_console(up))) + return false; + + /* + * @up->cons is only modified under the port lock. Therefore it is + * certain that it cannot disappear here. + * + * @up->cons->node is added/removed from the console list under the + * port lock. Therefore it is certain that the registration status + * cannot change here, thus @up->cons->flags can be read directly. + */ + if (hlist_unhashed_lockless(&up->cons->node) || + !(up->cons->flags & CON_NBCON) || + !up->cons->write_atomic) { + return false; + } + + return true; +} + +/* Only for internal port lock wrapper usage. */ +static inline bool __uart_port_nbcon_try_acquire(struct uart_port *up) +{ + if (!__uart_port_using_nbcon(up)) + return true; + + return nbcon_device_try_acquire(up->cons); +} + +/* Only for internal port lock wrapper usage. */ +static inline void __uart_port_nbcon_acquire(struct uart_port *up) +{ + if (!__uart_port_using_nbcon(up)) + return; + + while (!nbcon_device_try_acquire(up->cons)) + cpu_relax(); +} + +/* Only for internal port lock wrapper usage. */ +static inline void __uart_port_nbcon_release(struct uart_port *up) +{ + if (!__uart_port_using_nbcon(up)) + return; + + nbcon_device_release(up->cons); +} + /** * uart_port_lock - Lock the UART port * @up: Pointer to UART port structure @@ -632,6 +688,7 @@ static inline void uart_port_set_cons(struct uart_port *up, struct console *con) static inline void uart_port_lock(struct uart_port *up) { spin_lock(&up->lock); + __uart_port_nbcon_acquire(up); } /** @@ -641,6 +698,7 @@ static inline void uart_port_lock(struct uart_port *up) static inline void uart_port_lock_irq(struct uart_port *up) { spin_lock_irq(&up->lock); + __uart_port_nbcon_acquire(up); } /** @@ -651,6 +709,7 @@ static inline void uart_port_lock_irq(struct uart_port *up) static inline void uart_port_lock_irqsave(struct uart_port *up, unsigned long *flags) { spin_lock_irqsave(&up->lock, *flags); + __uart_port_nbcon_acquire(up); } /** @@ -661,7 +720,15 @@ static inline void uart_port_lock_irqsave(struct uart_port *up, unsigned long *f */ static inline bool uart_port_trylock(struct uart_port *up) { - return spin_trylock(&up->lock); + if (!spin_trylock(&up->lock)) + return false; + + if (!__uart_port_nbcon_try_acquire(up)) { + spin_unlock(&up->lock); + return false; + } + + return true; } /** @@ -673,7 +740,15 @@ static inline bool uart_port_trylock(struct uart_port *up) */ static inline bool uart_port_trylock_irqsave(struct uart_port *up, unsigned long *flags) { - return spin_trylock_irqsave(&up->lock, *flags); + if (!spin_trylock_irqsave(&up->lock, *flags)) + return false; + + if (!__uart_port_nbcon_try_acquire(up)) { + spin_unlock_irqrestore(&up->lock, *flags); + return false; + } + + return true; } /** @@ -682,6 +757,7 @@ static inline bool uart_port_trylock_irqsave(struct uart_port *up, unsigned long */ static inline void uart_port_unlock(struct uart_port *up) { + __uart_port_nbcon_release(up); spin_unlock(&up->lock); } @@ -691,6 +767,7 @@ static inline void uart_port_unlock(struct uart_port *up) */ static inline void uart_port_unlock_irq(struct uart_port *up) { + __uart_port_nbcon_release(up); spin_unlock_irq(&up->lock); } @@ -701,6 +778,7 @@ static inline void uart_port_unlock_irq(struct uart_port *up) */ static inline void uart_port_unlock_irqrestore(struct uart_port *up, unsigned long flags) { + __uart_port_nbcon_release(up); spin_unlock_irqrestore(&up->lock, flags); }