48 lines
1.5 KiB
Diff
48 lines
1.5 KiB
Diff
Subject: drivers-tty-pl011-irq-disable-madness.patch
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Tue, 08 Jan 2013 21:36:51 +0100
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/3.10/patches-3.10.4-rt1.tar.xz
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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 | 15 ++++++++++-----
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1 file changed, 10 insertions(+), 5 deletions(-)
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Index: linux-stable/drivers/tty/serial/amba-pl011.c
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===================================================================
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--- linux-stable.orig/drivers/tty/serial/amba-pl011.c
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+++ linux-stable/drivers/tty/serial/amba-pl011.c
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@@ -1923,13 +1923,19 @@ pl011_console_write(struct console *co,
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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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@@ -1951,8 +1957,7 @@ pl011_console_write(struct console *co,
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writew(old_cr, uap->port.membase + UART011_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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