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Message-Id: <20200602140058.3656-4-johan@kernel.org>
Date: Tue, 2 Jun 2020 16:00:57 +0200
From: Johan Hovold <johan@...nel.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jslaby@...e.com>,
Dmitry Safonov <0x7f454c46@...il.com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
Johan Hovold <johan@...nel.org>
Subject: [PATCH 3/4] serial: core: fix sysrq overhead regression
Commit 8e20fc391711 ("serial_core: Move sysrq functions from header
file") converted the inline sysrq helpers to exported functions which
are now called for every received character and break signal also on
systems without CONFIG_MAGIC_SYSRQ_SERIAL instead of being optimised
away by the compiler.
Inlining these helpers again also avoids the function call overhead when
CONFIG_MAGIC_SYSRQ_SERIAL is enabled.
Fixes: 8e20fc391711 ("serial_core: Move sysrq functions from header file")
Cc: Dmitry Safonov <0x7f454c46@...il.com>
Signed-off-by: Johan Hovold <johan@...nel.org>
---
drivers/tty/serial/serial_core.c | 80 +-----------------------------
include/linux/serial_core.h | 85 ++++++++++++++++++++++++++++++--
2 files changed, 84 insertions(+), 81 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index f6cf9cc4ce69..a714402dcf4e 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -41,8 +41,6 @@ static struct lock_class_key port_lock_key;
#define HIGH_BITS_OFFSET ((sizeof(long)-sizeof(int))*8)
-#define SYSRQ_TIMEOUT (HZ * 5)
-
static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
struct ktermios *old_termios);
static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
@@ -3163,7 +3161,7 @@ static DECLARE_WORK(sysrq_enable_work, uart_sysrq_on);
* Returns false if @ch is out of enabling sequence and should be
* handled some other way, true if @ch was consumed.
*/
-static bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
+bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
{
int sysrq_toggle_seq_len = strlen(sysrq_toggle_seq);
@@ -3186,83 +3184,9 @@ static bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
port->sysrq = 0;
return true;
}
-#else
-static inline bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch)
-{
- return false;
-}
+EXPORT_SYMBOL_GPL(uart_try_toggle_sysrq);
#endif
-int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
-{
- if (!IS_ENABLED(CONFIG_MAGIC_SYSRQ_SERIAL))
- return 0;
-
- if (!port->has_sysrq || !port->sysrq)
- return 0;
-
- if (ch && time_before(jiffies, port->sysrq)) {
- if (sysrq_mask()) {
- handle_sysrq(ch);
- port->sysrq = 0;
- return 1;
- }
- if (uart_try_toggle_sysrq(port, ch))
- return 1;
- }
- port->sysrq = 0;
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(uart_handle_sysrq_char);
-
-int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch)
-{
- if (!IS_ENABLED(CONFIG_MAGIC_SYSRQ_SERIAL))
- return 0;
-
- if (!port->has_sysrq || !port->sysrq)
- return 0;
-
- if (ch && time_before(jiffies, port->sysrq)) {
- if (sysrq_mask()) {
- port->sysrq_ch = ch;
- port->sysrq = 0;
- return 1;
- }
- if (uart_try_toggle_sysrq(port, ch))
- return 1;
- }
- port->sysrq = 0;
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(uart_prepare_sysrq_char);
-
-/*
- * We do the SysRQ and SAK checking like this...
- */
-int uart_handle_break(struct uart_port *port)
-{
- struct uart_state *state = port->state;
-
- if (port->handle_break)
- port->handle_break(port);
-
- if (port->has_sysrq && uart_console(port)) {
- if (!port->sysrq) {
- port->sysrq = jiffies + SYSRQ_TIMEOUT;
- return 1;
- }
- port->sysrq = 0;
- }
-
- if (port->flags & UPF_SAK)
- do_SAK(state->port.tty);
- return 0;
-}
-EXPORT_SYMBOL_GPL(uart_handle_break);
-
EXPORT_SYMBOL(uart_write_wakeup);
EXPORT_SYMBOL(uart_register_driver);
EXPORT_SYMBOL(uart_unregister_driver);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 858c5dd926ad..a8a213b71553 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -460,8 +460,49 @@ extern void uart_handle_cts_change(struct uart_port *uport,
extern void uart_insert_char(struct uart_port *port, unsigned int status,
unsigned int overrun, unsigned int ch, unsigned int flag);
-extern int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch);
-extern int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch);
+#ifdef CONFIG_MAGIC_SYSRQ_SERIAL
+
+#define SYSRQ_TIMEOUT (HZ * 5)
+
+bool uart_try_toggle_sysrq(struct uart_port *port, unsigned int ch);
+
+static inline int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
+{
+ if (!port->has_sysrq || !port->sysrq)
+ return 0;
+
+ if (ch && time_before(jiffies, port->sysrq)) {
+ if (sysrq_mask()) {
+ handle_sysrq(ch);
+ port->sysrq = 0;
+ return 1;
+ }
+ if (uart_try_toggle_sysrq(port, ch))
+ return 1;
+ }
+ port->sysrq = 0;
+
+ return 0;
+}
+
+static inline int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch)
+{
+ if (!port->has_sysrq || !port->sysrq)
+ return 0;
+
+ if (ch && time_before(jiffies, port->sysrq)) {
+ if (sysrq_mask()) {
+ port->sysrq_ch = ch;
+ port->sysrq = 0;
+ return 1;
+ }
+ if (uart_try_toggle_sysrq(port, ch))
+ return 1;
+ }
+ port->sysrq = 0;
+
+ return 0;
+}
static inline void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long irqflags)
{
@@ -480,8 +521,46 @@ static inline void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned
if (sysrq_ch)
handle_sysrq(sysrq_ch);
}
+#else /* CONFIG_MAGIC_SYSRQ_SERIAL */
+static inline int uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
+{
+ return 0;
+}
-extern int uart_handle_break(struct uart_port *port);
+static inline int uart_prepare_sysrq_char(struct uart_port *port, unsigned int ch)
+{
+ return 0;
+}
+
+static inline void uart_unlock_and_check_sysrq(struct uart_port *port, unsigned long irqflags)
+{
+ spin_unlock_irqrestore(&port->lock, irqflags);
+}
+#endif /* CONFIG_MAGIC_SYSRQ_SERIAL */
+
+/*
+ * We do the SysRQ and SAK checking like this...
+ */
+static inline int uart_handle_break(struct uart_port *port)
+{
+ struct uart_state *state = port->state;
+
+ if (port->handle_break)
+ port->handle_break(port);
+
+#ifdef CONFIG_MAGIC_SYSRQ_SERIAL
+ if (port->has_sysrq && uart_console(port)) {
+ if (!port->sysrq) {
+ port->sysrq = jiffies + SYSRQ_TIMEOUT;
+ return 1;
+ }
+ port->sysrq = 0;
+ }
+#endif
+ if (port->flags & UPF_SAK)
+ do_SAK(state->port.tty);
+ return 0;
+}
/*
* UART_ENABLE_MS - determine if port should enable modem status irqs
--
2.26.2
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