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a68ff2c35e
- Raspberry Pi: Using the RT patches and select RT as PREEMPT - Pipewire changes to upvote itself to prio 95% nice -19 - Other small kernel tweaks and fixes
60 lines
1.8 KiB
Diff
60 lines
1.8 KiB
Diff
From 1db3dc8a6af68447b52efbbf8dbb4d210d23d57b Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Tue, 8 Jan 2013 21:36:51 +0100
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Subject: [PATCH 42/62] tty/serial/pl011: Make the locking work on RT
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The lock is a sleeping lock and local_irq_save() is not the optimsation
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we are looking for. Redo it to make it work on -RT and non-RT.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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drivers/tty/serial/amba-pl011.c | 17 +++++++++++------
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1 file changed, 11 insertions(+), 6 deletions(-)
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diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
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index c74eaf2552c3..38eb30b8491b 100644
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--- a/drivers/tty/serial/amba-pl011.c
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+++ b/drivers/tty/serial/amba-pl011.c
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@@ -2316,18 +2316,24 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
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{
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struct uart_amba_port *uap = amba_ports[co->index];
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unsigned int old_cr = 0, new_cr;
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- unsigned long flags;
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+ unsigned long flags = 0;
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int locked = 1;
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clk_enable(uap->clk);
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- local_irq_save(flags);
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+ /*
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+ * local_irq_save(flags);
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+ *
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+ * This local_irq_save() is nonsense. If we come in via sysrq
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+ * handling then interrupts are already disabled. Aside of
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+ * that the port.sysrq check is racy on SMP regardless.
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+ */
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if (uap->port.sysrq)
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locked = 0;
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else if (oops_in_progress)
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- locked = spin_trylock(&uap->port.lock);
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+ locked = spin_trylock_irqsave(&uap->port.lock, flags);
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else
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- spin_lock(&uap->port.lock);
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+ spin_lock_irqsave(&uap->port.lock, flags);
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/*
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* First save the CR then disable the interrupts
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@@ -2353,8 +2359,7 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
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pl011_write(old_cr, uap, REG_CR);
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if (locked)
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- spin_unlock(&uap->port.lock);
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- local_irq_restore(flags);
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+ spin_unlock_irqrestore(&uap->port.lock, flags);
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clk_disable(uap->clk);
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}
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--
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2.43.0
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