90 lines
3.2 KiB
Diff
90 lines
3.2 KiB
Diff
From 1822291e9247afa91b6f259f602964f1ac285553 Mon Sep 17 00:00:00 2001
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Message-Id: <1822291e9247afa91b6f259f602964f1ac285553.1601675152.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: Jason Wessel <jason.wessel@windriver.com>
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Date: Thu, 28 Jul 2011 12:42:23 -0500
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Subject: [PATCH 213/333] kgdb/serial: Short term workaround
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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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On 07/27/2011 04:37 PM, Thomas Gleixner wrote:
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> - KGDB (not yet disabled) is reportedly unusable on -rt right now due
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> to missing hacks in the console locking which I dropped on purpose.
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>
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To work around this in the short term you can use this patch, in
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addition to the clocksource watchdog patch that Thomas brewed up.
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Comments are welcome of course. Ultimately the right solution is to
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change separation between the console and the HW to have a polled mode
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+ work queue so as not to introduce any kind of latency.
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Thanks,
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Jason.
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---
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drivers/tty/serial/8250/8250_port.c | 3 +++
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include/linux/kdb.h | 2 ++
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kernel/debug/kdb/kdb_io.c | 2 ++
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3 files changed, 7 insertions(+)
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diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
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index 620cc8ee9828..0dec1d548a28 100644
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--- a/drivers/tty/serial/8250/8250_port.c
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+++ b/drivers/tty/serial/8250/8250_port.c
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@@ -31,6 +31,7 @@
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#include <linux/nmi.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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+#include <linux/kdb.h>
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#include <linux/uaccess.h>
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#include <linux/pm_runtime.h>
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#include <linux/ktime.h>
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@@ -3250,6 +3251,8 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s,
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if (port->sysrq || oops_in_progress)
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locked = 0;
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+ else if (in_kdb_printk())
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+ locked = spin_trylock_irqsave(&port->lock, flags);
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else
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spin_lock_irqsave(&port->lock, flags);
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diff --git a/include/linux/kdb.h b/include/linux/kdb.h
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index 68bd88223417..e033b25b0b72 100644
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--- a/include/linux/kdb.h
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+++ b/include/linux/kdb.h
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@@ -167,6 +167,7 @@ extern __printf(2, 0) int vkdb_printf(enum kdb_msgsrc src, const char *fmt,
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extern __printf(1, 2) int kdb_printf(const char *, ...);
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typedef __printf(1, 2) int (*kdb_printf_t)(const char *, ...);
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+#define in_kdb_printk() (kdb_trap_printk)
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extern void kdb_init(int level);
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/* Access to kdb specific polling devices */
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@@ -201,6 +202,7 @@ extern int kdb_register_flags(char *, kdb_func_t, char *, char *,
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extern int kdb_unregister(char *);
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#else /* ! CONFIG_KGDB_KDB */
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static inline __printf(1, 2) int kdb_printf(const char *fmt, ...) { return 0; }
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+#define in_kdb_printk() (0)
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static inline void kdb_init(int level) {}
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static inline int kdb_register(char *cmd, kdb_func_t func, char *usage,
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char *help, short minlen) { return 0; }
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diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
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index 6a4b41484afe..197cb422f6e1 100644
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--- a/kernel/debug/kdb/kdb_io.c
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+++ b/kernel/debug/kdb/kdb_io.c
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@@ -857,9 +857,11 @@ int kdb_printf(const char *fmt, ...)
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va_list ap;
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int r;
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+ kdb_trap_printk++;
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va_start(ap, fmt);
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r = vkdb_printf(KDB_MSGSRC_INTERNAL, fmt, ap);
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va_end(ap);
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+ kdb_trap_printk--;
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return r;
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}
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--
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2.17.1
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