Account lost messages in pritk-safe and printk-safe-nmi
contexts and report those numbers during printk_safe_flush().
The patch also moves lost message counter to struct
`printk_safe_seq_buf' instead of having dedicated static
counters - this simplifies the code.
Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
Reviewed-by: Petr Mladek <pmla...@suse.com>
---
kernel/printk/internal.h | 17 -----------------
kernel/printk/printk.c | 10 ----------
kernel/printk/printk_safe.c | 18 +++++++++++++++---
3 files changed, 15 insertions(+), 30 deletions(-)
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 97cee4f482f4..d2456020120c 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -16,23 +16,6 @@
*/
#include <linux/percpu.h>
-#ifdef CONFIG_PRINTK_NMI
-
-extern atomic_t nmi_message_lost;
-static inline int get_nmi_message_lost(void)
-{
- return atomic_xchg(&nmi_message_lost, 0);
-}
-
-#else /* CONFIG_PRINTK_NMI */
-
-static inline int get_nmi_message_lost(void)
-{
- return 0;
-}
-
-#endif /* CONFIG_PRINTK_NMI */
-
#ifdef CONFIG_PRINTK
#define PRINTK_SAFE_CONTEXT_MASK 0x7fffffff
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 335b0fcb538e..6ec61ae0d122 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1677,7 +1677,6 @@ asmlinkage int vprintk_emit(int facility, int level,
unsigned long flags;
int this_cpu;
int printed_len = 0;
- int nmi_message_lost;
bool in_sched = false;
/* cpu currently holding logbuf_lock in this function */
static unsigned int logbuf_cpu = UINT_MAX;
@@ -1728,15 +1727,6 @@ asmlinkage int vprintk_emit(int facility, int level,
strlen(recursion_msg));
}
- nmi_message_lost = get_nmi_message_lost();
- if (unlikely(nmi_message_lost)) {
- text_len = scnprintf(textbuf, sizeof(textbuf),
- "BAD LUCK: lost %d message(s) from NMI
context!",
- nmi_message_lost);
- printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
- NULL, 0, textbuf, text_len);
- }
-
/*
* The printf needs to come first; we need the syslog
* prefix which might be passed-in as a parameter.
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index 9e8ef6a2070c..cd5160112374 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -42,10 +42,13 @@
static int printk_safe_irq_ready;
#define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \
- sizeof(atomic_t) - sizeof(struct irq_work))
+ sizeof(atomic_t) - \
+ sizeof(atomic_t) - \
+ sizeof(struct irq_work))
struct printk_safe_seq_buf {
atomic_t len; /* length of written data */
+ atomic_t message_lost;
struct irq_work work; /* IRQ work that flushes the buffer */
unsigned char buffer[SAFE_LOG_BUF_LEN];
};
@@ -55,7 +58,6 @@ static DEFINE_PER_CPU(int, printk_context);
#ifdef CONFIG_PRINTK_NMI
static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq);
-atomic_t nmi_message_lost;
#endif
/*
@@ -79,7 +81,7 @@ static int printk_safe_log_store(struct printk_safe_seq_buf
*s,
/* The trailing '\0' is not counted into len. */
if (len >= sizeof(s->buffer) - 1) {
- atomic_inc(&nmi_message_lost);
+ atomic_inc(&s->message_lost);
return 0;
}
@@ -168,6 +170,14 @@ static int printk_safe_flush_buffer(const char *start,
size_t len)
return len;
}
+static void report_message_lost(struct printk_safe_seq_buf *s)
+{
+ int lost = atomic_xchg(&s->message_lost, 0);
+
+ if (lost)
+ printk_deferred("Lost %d message(s)!\n", lost);
+}
+
/*
* Flush data from the associated per-CPU buffer. The function
* can be called either via IRQ work or independently.
@@ -224,6 +234,8 @@ static void __printk_safe_flush(struct irq_work *work)
if (atomic_cmpxchg(&s->len, len, 0) != len)
goto more;
+ report_message_lost(s);
+
out:
raw_spin_unlock_irqrestore(&read_lock, flags);
}
--
2.11.0
