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From: John Ogness <john.ogness@linutronix.de>
Date: Tue, 12 Feb 2019 15:29:41 +0100
Subject: [PATCH 03/25] printk-rb: define ring buffer struct and initializer
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.10-rt5.tar.xz
See Documentation/printk-ringbuffer.txt for details about the
initializer arguments.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/printk_ringbuffer.h | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
--- a/include/linux/printk_ringbuffer.h
+++ b/include/linux/printk_ringbuffer.h
@@ -10,6 +10,20 @@ struct prb_cpulock {
unsigned long __percpu *irqflags;
};
+struct printk_ringbuffer {
+ void *buffer;
+ unsigned int size_bits;
+
+ u64 seq;
+
+ atomic_long_t tail;
+ atomic_long_t head;
+ atomic_long_t reserve;
+
+ struct prb_cpulock *cpulock;
+ atomic_t ctx;
+};
+
#define DECLARE_STATIC_PRINTKRB_CPULOCK(name) \
static DEFINE_PER_CPU(unsigned long, _##name##_percpu_irqflags); \
static struct prb_cpulock name = { \
@@ -17,6 +31,20 @@ static struct prb_cpulock name = { \
.irqflags = &_##name##_percpu_irqflags, \
}
+#define DECLARE_STATIC_PRINTKRB(name, szbits, cpulockptr) \
+static char _##name##_buffer[1 << (szbits)] \
+ __aligned(__alignof__(long)); \
+static struct printk_ringbuffer name = { \
+ .buffer = &_##name##_buffer[0], \
+ .size_bits = szbits, \
+ .seq = 0, \
+ .tail = ATOMIC_LONG_INIT(-111 * sizeof(long)), \
+ .head = ATOMIC_LONG_INIT(-111 * sizeof(long)), \
+ .reserve = ATOMIC_LONG_INIT(-111 * sizeof(long)), \
+ .cpulock = cpulockptr, \
+ .ctx = ATOMIC_INIT(0), \
+}
+
/* utility functions */
void prb_lock(struct prb_cpulock *cpu_lock, unsigned int *cpu_store);
void prb_unlock(struct prb_cpulock *cpu_lock, unsigned int cpu_store);
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