[PATCH 2/5] printk/console: Rename has_preferred_console to need_default_console

Petr Mladek
2021-11-22T13:27:29Z

The logic around the variable @has_preferred_console made my head
spin many times. Part of the problem is the ambiguous name.

There is the variable @preferred_console. It points to the last
non-braille console in @console_cmdline array. This array contains
consoles preferred via the command line, device tree, or SPCR.

Then there is the variable @has_preferred_console. It is set to
"true" when @preferred_console is enabled or when a console with
tty binding gets enabled by default.

It might get reset back by the magic condition:

if (!has_preferred_console || bcon || !console_drivers)
has_preferred_console = preferred_console >= 0;

It is a puzzle. Dumb explanation is that it gets re-evaluated
when:

+ it was not set before (see above when it gets set)
+ there is still an early console enabled (bcon)
+ there is no console enabled (!console_drivers)

This is still a puzzle.

It gets more clear when we see where the value is checked. The only
meaning of the variable is to decide whether we should try to enable
the new console by default.

Rename the variable according to the single situation where
the value is checked.

The rename requires an inverted logic. Otherwise, it is a simple
search & replace. It does not change the functionality.

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
kernel/printk/printk.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 1acbe39dd47c..4c5f496877b0 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -280,7 +280,7 @@ static struct console *exclusive_console;
static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];

static int preferred_console = -1;
-static bool has_preferred_console;
+static bool need_default_console = true;
int console_set_on_cmdline;
EXPORT_SYMBOL(console_set_on_cmdline);

@@ -2894,7 +2894,7 @@ static int try_enable_preferred_console(struct console *newcon,
newcon->flags |= CON_ENABLED;
if (i == preferred_console) {
newcon->flags |= CON_CONSDEV;
- has_preferred_console = true;
+ need_default_console = false;
}
return 0;
}
@@ -2923,7 +2923,7 @@ static void try_enable_default_console(struct console *newcon)

if (newcon->device) {
newcon->flags |= CON_CONSDEV;
- has_preferred_console = true;
+ need_default_console = false;
}
}

@@ -2974,15 +2974,15 @@ void register_console(struct console *newcon)
if (console_drivers && console_drivers->flags & CON_BOOT)
bcon = console_drivers;

- if (!has_preferred_console || bcon || !console_drivers)
- has_preferred_console = preferred_console >= 0;
+ if (need_default_console || bcon || !console_drivers)
+ need_default_console = preferred_console < 0;

/*
* See if we want to use this console driver. If we
* didn't select a console we take the first one
* that registers here.
*/
- if (!has_preferred_console)
+ if (need_default_console)
try_enable_default_console(newcon);

/* See if this console matches one we selected on the command line */
--
2.26.2