Re: [PATCH next v4 07/15] printk: introduce CONSOLE_LOG_MAX

[Petr Mladek]

On Wed 2021-03-03 11:15:20, John Ogness wrote:
> Instead of using "LOG_LINE_MAX + PREFIX_MAX" for temporary buffer
> sizes, introduce CONSOLE_LOG_MAX. This represents the maximum size
> that is allowed to be printed to the console for a single record.
> 
> Signed-off-by: John Ogness 

Reviewed-by: Petr Mladek 

Best Regards,
Petr

[PATCH next v4 07/15] printk: introduce CONSOLE_LOG_MAX

[John Ogness]

Instead of using "LOG_LINE_MAX + PREFIX_MAX" for temporary buffer
sizes, introduce CONSOLE_LOG_MAX. This represents the maximum size
that is allowed to be printed to the console for a single record.

Signed-off-by: John Ogness 
---
 kernel/printk/printk.c | 20 
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 9a5f9ccc46ea..2c8873fa2f29 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -410,7 +410,12 @@ static u64 clear_seq;
 #else
 #define PREFIX_MAX 32
 #endif
-#define LOG_LINE_MAX   (1024 - PREFIX_MAX)
+
+/* the maximum size of a formatted record (i.e. with prefix added per line) */
+#define CONSOLE_LOG_MAX1024
+
+/* the maximum size allowed to be reserved for a record */
+#define LOG_LINE_MAX   (CONSOLE_LOG_MAX - PREFIX_MAX)
 
 #define LOG_LEVEL(v)   ((v) & 0x07)
 #define LOG_FACILITY(v)((v) >> 3 & 0xff)
@@ -1472,11 +1477,11 @@ static int syslog_print(char __user *buf, int size)
char *text;
int len = 0;
 
-   text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
+   text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
 
-   prb_rec_init_rd(, , text, LOG_LINE_MAX + PREFIX_MAX);
+   prb_rec_init_rd(, , text, CONSOLE_LOG_MAX);
 
while (size > 0) {
size_t n;
@@ -1542,7 +1547,7 @@ static int syslog_print_all(char __user *buf, int size, 
bool clear)
u64 seq;
bool time;
 
-   text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
+   text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
 
@@ -1554,7 +1559,7 @@ static int syslog_print_all(char __user *buf, int size, 
bool clear)
 */
seq = find_first_fitting_seq(clear_seq, -1, size, true, time);
 
-   prb_rec_init_rd(, , text, LOG_LINE_MAX + PREFIX_MAX);
+   prb_rec_init_rd(, , text, CONSOLE_LOG_MAX);
 
len = 0;
prb_for_each_record(seq, prb, seq, ) {
@@ -2187,8 +2192,7 @@ EXPORT_SYMBOL(printk);
 
 #else /* CONFIG_PRINTK */
 
-#define LOG_LINE_MAX   0
-#define PREFIX_MAX 0
+#define CONSOLE_LOG_MAX0
 #define printk_timefalse
 
 #define prb_read_valid(rb, seq, r) false
@@ -2506,7 +2510,7 @@ static inline int can_use_console(void)
 void console_unlock(void)
 {
static char ext_text[CONSOLE_EXT_LOG_MAX];
-   static char text[LOG_LINE_MAX + PREFIX_MAX];
+   static char text[CONSOLE_LOG_MAX];
unsigned long flags;
bool do_cond_resched, retry;
struct printk_info info;
-- 
2.20.1