2022-11-14 16:53:13

by John Ogness

Subject: [PATCH printk v4 16/39] printk: console_is_usable: use console_srcu_read_flags

All users of console_is_usable() are SRCU iterators. Use the
appropriate wrapper function to locklessly read the flags.

Signed-off-by: John Ogness <[email protected]>
---
kernel/printk/printk.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 3d9e5bb1a50b..bc563972e468 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2708,11 +2708,13 @@ static bool abandon_console_lock_in_panic(void)
* Check if the given console is currently capable and allowed to print
* records.
*
- * Requires the console_lock.
+ * Requires the console_srcu_read_lock.
*/
static inline bool console_is_usable(struct console *con)
{
- if (!(con->flags & CON_ENABLED))
+ short flags = console_srcu_read_flags(con);
+
+ if (!(flags & CON_ENABLED))
return false;

if (!con->write)
@@ -2723,8 +2725,7 @@ static inline bool console_is_usable(struct console *con)
* allocated. So unless they're explicitly marked as being able to
* cope (CON_ANYTIME) don't call them until this CPU is officially up.
*/
- if (!cpu_online(raw_smp_processor_id()) &&
- !(con->flags & CON_ANYTIME))
+ if (!cpu_online(raw_smp_processor_id()) && !(flags & CON_ANYTIME))
return false;

return true;
--
2.30.2

2022-11-15 13:28:42

by Petr Mladek

Subject: Re: [PATCH printk v4 16/39] printk: console_is_usable: use console_srcu_read_flags

On Mon 2022-11-14 17:35:09, John Ogness wrote:
> All users of console_is_usable() are SRCU iterators. Use the
> appropriate wrapper function to locklessly read the flags.
>
> Signed-off-by: John Ogness <[email protected]>

Reviewed-by: Petr Mladek <[email protected]>

Best Regards,
Petr