58 lines
2.0 KiB
Diff
58 lines
2.0 KiB
Diff
From ae9e3f8cfe11f06deac2238dfc419d9b202ea1c2 Mon Sep 17 00:00:00 2001
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Message-Id: <ae9e3f8cfe11f06deac2238dfc419d9b202ea1c2.1601675152.git.zanussi@kernel.org>
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In-Reply-To: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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References: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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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 165/333] tty/serial/pl011: Make the locking work on RT
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.148-rt64.tar.xz
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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 | 15 ++++++++++-----
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1 file changed, 10 insertions(+), 5 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 45e4f2952143..f4a01c7909fb 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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@@ -2214,13 +2214,19 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
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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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@@ -2246,8 +2252,7 @@ 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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2.17.1
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