On 03/27/2017 05:14 PM, Petr Mladek wrote:
On Mon 2017-03-20 13:03:00, Aleksey Makarov wrote:
[..]
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fd752f0c8ef1..462036e7a767 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1909,8 +1909,28 @@ static int __add_preferred_console(char *name, int idx,
char *options,
i < MAX_CMDLINECONSOLES && c->name[0];
i++, c++) {
if (strcmp(c->name, name) == 0 && c->index == idx) {
- if (!brl_options)
- preferred_console = i;
+ int last;
+
+ if (brl_options)
+ return 0;
+
+ /*
+ * Maintain an invariant that will help to find if
+ * the matching console is preferred, see
+ * register_console():
+ *
+ * The last non-braille console is always
+ * the preferred one.
+ */
+ for (last = MAX_CMDLINECONSOLES - 1;
+ last >= 0 && !console_cmdline[last].name[0];
+ last--)
+ ;
This is a rather non-trivial code to find the last element.
I might make sense to count it in a global variable.
Then we might remove the check for console_cmdline[i].name[0]
also in the other for cycles and make them better readable.
Having an additional variable console_cmdline_last pointing to the last element
would require maintaining consistency between this variable and
contents of console_cmdline. For the code we have it is not hard, but when code
is changed we need to check this. Also there exists preferred_console that
has almost the same meaning but it points not to the last element, but to the
last non-braille element. Also we need to have a special value (-1) for this
variable for empty array. So I personally would instead try to rewrite this:
for (last = MAX_CMDLINECONSOLES - 1; last >= 0; last--)
if (console_cmdline[last].name[0])
break;
Is it better? If not, I will send a version with console_cmdline_last.
+
+ if (i != last)
+ swap(console_cmdline[i], console_cmdline[last]);
I was not aware of the swap() function. It is great to know ;-)
Yes, same for me. Thanks to Sergey Senozhatsky.
Thank you for review
Aleksey Makarov
