On Wed, 2012-07-11 at 12:33 +0200, Kay Sievers wrote:
> Hey Joe,
>
> what do you think of 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.
Better version with better range checking and _INIT() to reset the
string for re-use. It prints:
[ 0.000000] Kernel command line: root=/dev/sda2 ...
[ 0.000000] 1:-12 -34 -56 -78 -90
[ 0.000000] 2:-12 -34 -56 --90
[ 0.000000] 3:-12 -34 --90
[ 0.000000] 4:+12 +34 +-90
[ 0.000000] 5:~12 ~34 ~-90
[ 0.000000] PID hash table entries: 2048 (order: 2, 16384 bytes)
Thanks,
Kay
diff --git a/kernel/printk.c b/kernel/printk.c
index dba1821..1490153 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -48,6 +48,39 @@
#define CREATE_TRACE_POINTS
#include <trace/events/printk.h>
+#define CATSTR_INIT(name) \
+ name##_len = 0;
+
+#define CATSTR_DEFINE(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 r;
+
+ if (*len == size)
+ return -EINVAL;
+
+ va_start(args, fmt);
+ r = vsnprintf(s + *len, size - *len, fmt, args);
+ va_end(args);
+
+ if (r >= size - *len) {
+ *len = size;
+ return -EINVAL;
+ }
+
+ *len += r;
+ s[*len] = '\0';
+ return r;
+}
+
/*
* Architectures can override it:
*/
@@ -668,6 +701,47 @@ void __init setup_log_buf(int early)
char *new_log_buf;
int free;
+ CATSTR_DEFINE(line, 24)
+ CATSTR_DEFINE(line2, 16)
+ CATSTR_DEFINE(line3, 12)
+
+ pr_cat(line, "1:");
+ pr_cat(line, "-%i ", 12);
+ pr_cat(line, "-%i ", 34);
+ pr_cat(line, "-%i ", 56);
+ pr_cat(line, "-%i ", 78);
+ pr_warn("%s-%i\n", line, 90);
+
+ pr_cat(line2, "2:");
+ pr_cat(line2, "-%i ", 12);
+ pr_cat(line2, "-%i ", 34);
+ pr_cat(line2, "-%i ", 56);
+ pr_cat(line2, "-%i ", 78);
+ pr_warn("%s-%i\n", line2, 90);
+
+ pr_cat(line3, "3:");
+ pr_cat(line3, "-%i ", 12);
+ pr_cat(line3, "-%i ", 34);
+ pr_cat(line3, "-%i ", 56);
+ pr_cat(line3, "-%i ", 78);
+ pr_warn("%s-%i\n", line3, 90);
+
+ CATSTR_INIT(line3)
+ pr_cat(line3, "4:");
+ pr_cat(line3, "+%i ", 12);
+ pr_cat(line3, "+%i ", 34);
+ pr_cat(line3, "+%i ", 56);
+ pr_cat(line3, "+%i ", 78);
+ pr_warn("%s-%i\n", line3, 90);
+
+ CATSTR_INIT(line3)
+ pr_cat(line3, "5:");
+ pr_cat(line3, "~%i ", 12);
+ pr_cat(line3, "~%i ", 34);
+ pr_cat(line3, "~%i ", 56);
+ pr_cat(line3, "~%i ", 78);
+ pr_warn("%s-%i\n", line3, 90);
+
if (!new_log_buf_len)
return;
--
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