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-rw-r--r--debian/patches-rt/0267-tty-serial-pl011-Make-the-locking-work-on-RT.patch60
1 files changed, 60 insertions, 0 deletions
diff --git a/debian/patches-rt/0267-tty-serial-pl011-Make-the-locking-work-on-RT.patch b/debian/patches-rt/0267-tty-serial-pl011-Make-the-locking-work-on-RT.patch
new file mode 100644
index 000000000..73b68ab8d
--- /dev/null
+++ b/debian/patches-rt/0267-tty-serial-pl011-Make-the-locking-work-on-RT.patch
@@ -0,0 +1,60 @@
+From 822739997ff16caa50f619a00344655f21d65a4b Mon Sep 17 00:00:00 2001
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Tue, 8 Jan 2013 21:36:51 +0100
+Subject: [PATCH 267/323] tty/serial/pl011: Make the locking work on RT
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
+
+The lock is a sleeping lock and local_irq_save() is not the optimsation
+we are looking for. Redo it to make it work on -RT and non-RT.
+
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+---
+ drivers/tty/serial/amba-pl011.c | 17 +++++++++++------
+ 1 file changed, 11 insertions(+), 6 deletions(-)
+
+diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
+index d4a93a94b4ca..275c625e3eb9 100644
+--- a/drivers/tty/serial/amba-pl011.c
++++ b/drivers/tty/serial/amba-pl011.c
+@@ -2207,18 +2207,24 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
+ {
+ struct uart_amba_port *uap = amba_ports[co->index];
+ unsigned int old_cr = 0, new_cr;
+- unsigned long flags;
++ unsigned long flags = 0;
+ int locked = 1;
+
+ clk_enable(uap->clk);
+
+- local_irq_save(flags);
++ /*
++ * local_irq_save(flags);
++ *
++ * This local_irq_save() is nonsense. If we come in via sysrq
++ * handling then interrupts are already disabled. Aside of
++ * that the port.sysrq check is racy on SMP regardless.
++ */
+ if (uap->port.sysrq)
+ locked = 0;
+ else if (oops_in_progress)
+- locked = spin_trylock(&uap->port.lock);
++ locked = spin_trylock_irqsave(&uap->port.lock, flags);
+ else
+- spin_lock(&uap->port.lock);
++ spin_lock_irqsave(&uap->port.lock, flags);
+
+ /*
+ * First save the CR then disable the interrupts
+@@ -2244,8 +2250,7 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
+ pl011_write(old_cr, uap, REG_CR);
+
+ if (locked)
+- spin_unlock(&uap->port.lock);
+- local_irq_restore(flags);
++ spin_unlock_irqrestore(&uap->port.lock, flags);
+
+ clk_disable(uap->clk);
+ }
+--
+2.43.0
+