Hey Joe,
what do you think this?
It would make composing continuation lines at the caller side entirely
race-free, and it might fit into the usual pattern.
The more interesting thing, this would allow us to completely race-free
use the dev_printk() calls with continuation content, which we should
avoid otherwise for integrity reasons.
The patch below is just hacked it into the printk.c file to illustrate
the idea. It prints:
[ 0.000000] Kernel command line: root=/dev/sda2 ...
[ 0.000000] 12 34 56 78
[ 0.000000] PID hash table entries: 2048 (order: 2, 16384 bytes)
5,96,0;Kernel command line: root=/dev/sda2 ...
4,97,0;12 34 56 78
6,98,0;PID hash table entries: 2048 (order: 2, 16384 bytes)
Thanks,
Kay
diff --git a/kernel/printk.c b/kernel/printk.c
index dba1821..1fd00b0 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -48,6 +48,32 @@
#define CREATE_TRACE_POINTS
#include <trace/events/printk.h>
+#define CATSTR(name, max) \
+ char name[max]; \
+ size_t _##name_len = 0; \
+ size_t _##name_max = max;
+
+#define pr_cat(name, fmt, ...) \
+ _catstr(name, &_##name_len, _##name_max, fmt, ##__VA_ARGS__)
+
+ssize_t _catstr(char *s, size_t *len, size_t size, const char *fmt, ...)
+{
+ va_list args;
+ size_t l = *len;
+ size_t r;
+
+ va_start(args, fmt);
+ r = vsnprintf(s + l, size - l, fmt, args);
+ va_end(args);
+
+ if (r >= size - l)
+ return -EINVAL;
+
+ *len += r;
+ s[*len] = '\0';
+ return r;
+}
+
/*
* Architectures can override it:
*/
@@ -668,6 +694,12 @@ void __init setup_log_buf(int early)
char *new_log_buf;
int free;
+ CATSTR(line, 80);
+ pr_cat(line, "%i ", 12);
+ pr_cat(line, "%i ", 34);
+ pr_cat(line, "%i ", 56);
+ pr_warn("%s%i\n", line, 78);
+
if (!new_log_buf_len)
return;
--
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