mirror of
https://github.com/linuxkit/linuxkit.git
synced 2025-07-31 14:41:10 +00:00
137 lines
3.0 KiB
Diff
137 lines
3.0 KiB
Diff
From: John Ogness <john.ogness@linutronix.de>
|
|
Date: Fri, 11 Dec 2020 00:55:25 +0106
|
|
Subject: [PATCH 16/28] printk: track/limit recursion
|
|
|
|
Limit printk() recursion to 1 level. This is enough to print a
|
|
stacktrace for the printk call, should a WARN or BUG occur.
|
|
|
|
Signed-off-by: John Ogness <john.ogness@linutronix.de>
|
|
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
---
|
|
kernel/printk/printk.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++--
|
|
1 file changed, 71 insertions(+), 3 deletions(-)
|
|
|
|
--- a/kernel/printk/printk.c
|
|
+++ b/kernel/printk/printk.c
|
|
@@ -1940,6 +1940,65 @@ static void call_console_drivers(const c
|
|
}
|
|
}
|
|
|
|
+#ifdef CONFIG_PRINTK_NMI
|
|
+#define NUM_RECURSION_CTX 2
|
|
+#else
|
|
+#define NUM_RECURSION_CTX 1
|
|
+#endif
|
|
+
|
|
+struct printk_recursion {
|
|
+ char count[NUM_RECURSION_CTX];
|
|
+};
|
|
+
|
|
+static DEFINE_PER_CPU(struct printk_recursion, percpu_printk_recursion);
|
|
+static char printk_recursion_count[NUM_RECURSION_CTX];
|
|
+
|
|
+static char *printk_recursion_counter(void)
|
|
+{
|
|
+ struct printk_recursion *rec;
|
|
+ char *count;
|
|
+
|
|
+ if (!printk_percpu_data_ready()) {
|
|
+ count = &printk_recursion_count[0];
|
|
+ } else {
|
|
+ rec = this_cpu_ptr(&percpu_printk_recursion);
|
|
+
|
|
+ count = &rec->count[0];
|
|
+ }
|
|
+
|
|
+#ifdef CONFIG_PRINTK_NMI
|
|
+ if (in_nmi())
|
|
+ count++;
|
|
+#endif
|
|
+
|
|
+ return count;
|
|
+}
|
|
+
|
|
+static bool printk_enter_irqsave(unsigned long *flags)
|
|
+{
|
|
+ char *count;
|
|
+
|
|
+ local_irq_save(*flags);
|
|
+ count = printk_recursion_counter();
|
|
+ /* Only 1 level of recursion allowed. */
|
|
+ if (*count > 1) {
|
|
+ local_irq_restore(*flags);
|
|
+ return false;
|
|
+ }
|
|
+ (*count)++;
|
|
+
|
|
+ return true;
|
|
+}
|
|
+
|
|
+static void printk_exit_irqrestore(unsigned long flags)
|
|
+{
|
|
+ char *count;
|
|
+
|
|
+ count = printk_recursion_counter();
|
|
+ (*count)--;
|
|
+ local_irq_restore(flags);
|
|
+}
|
|
+
|
|
int printk_delay_msec __read_mostly;
|
|
|
|
static inline void printk_delay(void)
|
|
@@ -2040,11 +2099,13 @@ int vprintk_store(int facility, int leve
|
|
struct prb_reserved_entry e;
|
|
enum log_flags lflags = 0;
|
|
struct printk_record r;
|
|
+ unsigned long irqflags;
|
|
u16 trunc_msg_len = 0;
|
|
char prefix_buf[8];
|
|
u16 reserve_size;
|
|
va_list args2;
|
|
u16 text_len;
|
|
+ int ret = 0;
|
|
u64 ts_nsec;
|
|
|
|
/*
|
|
@@ -2055,6 +2116,9 @@ int vprintk_store(int facility, int leve
|
|
*/
|
|
ts_nsec = local_clock();
|
|
|
|
+ if (!printk_enter_irqsave(&irqflags))
|
|
+ return 0;
|
|
+
|
|
/*
|
|
* The sprintf needs to come first since the syslog prefix might be
|
|
* passed in as a parameter. An extra byte must be reserved so that
|
|
@@ -2092,7 +2156,8 @@ int vprintk_store(int facility, int leve
|
|
prb_commit(&e);
|
|
}
|
|
|
|
- return text_len;
|
|
+ ret = text_len;
|
|
+ goto out;
|
|
}
|
|
}
|
|
|
|
@@ -2108,7 +2173,7 @@ int vprintk_store(int facility, int leve
|
|
|
|
prb_rec_init_wr(&r, reserve_size + trunc_msg_len);
|
|
if (!prb_reserve(&e, prb, &r))
|
|
- return 0;
|
|
+ goto out;
|
|
}
|
|
|
|
/* fill message */
|
|
@@ -2130,7 +2195,10 @@ int vprintk_store(int facility, int leve
|
|
else
|
|
prb_final_commit(&e);
|
|
|
|
- return (text_len + trunc_msg_len);
|
|
+ ret = text_len + trunc_msg_len;
|
|
+out:
|
|
+ printk_exit_irqrestore(irqflags);
|
|
+ return ret;
|
|
}
|
|
|
|
asmlinkage int vprintk_emit(int facility, int level,
|