diff options
Diffstat (limited to 'debian/patches-rt/0021-printk-Track-registered-boot-consoles.patch')
| -rw-r--r-- | debian/patches-rt/0021-printk-Track-registered-boot-consoles.patch | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/debian/patches-rt/0021-printk-Track-registered-boot-consoles.patch b/debian/patches-rt/0021-printk-Track-registered-boot-consoles.patch new file mode 100644 index 0000000000..64ee0c4dbb --- /dev/null +++ b/debian/patches-rt/0021-printk-Track-registered-boot-consoles.patch @@ -0,0 +1,79 @@ +From: John Ogness <john.ogness@linutronix.de> +Date: Tue, 24 Oct 2023 14:13:14 +0000 +Subject: [PATCH 21/48] printk: Track registered boot consoles +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz + +Unfortunately it is not known if a boot console and a regular +(legacy or nbcon) console use the same hardware. For this reason +they must not be allowed to print simultaneously. + +For legacy consoles this is not an issue because they are +already synchronized with the boot consoles using the console +lock. However nbcon consoles can be triggered separately. + +Add a global flag @have_boot_console to identify if any boot +consoles are registered. This will be used in follow-up commits +to ensure that boot consoles and nbcon consoles cannot print +simultaneously. + +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Reviewed-by: Petr Mladek <pmladek@suse.com> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + kernel/printk/printk.c | 24 ++++++++++++++++++++++++ + 1 file changed, 24 insertions(+) + +--- a/kernel/printk/printk.c ++++ b/kernel/printk/printk.c +@@ -463,6 +463,14 @@ static int console_msg_format = MSG_FORM + /* syslog_lock protects syslog_* variables and write access to clear_seq. */ + static DEFINE_MUTEX(syslog_lock); + ++/* ++ * Specifies if a boot console is registered. If boot consoles are present, ++ * nbcon consoles cannot print simultaneously and must be synchronized by ++ * the console lock. This is because boot consoles and nbcon consoles may ++ * have mapped the same hardware. ++ */ ++static bool have_boot_console; ++ + #ifdef CONFIG_PRINTK + DECLARE_WAIT_QUEUE_HEAD(log_wait); + /* All 3 protected by @syslog_lock. */ +@@ -3518,6 +3526,9 @@ void register_console(struct console *ne + newcon->seq = 0; + } + ++ if (newcon->flags & CON_BOOT) ++ have_boot_console = true; ++ + /* + * If another context is actively using the hardware of this new + * console, it will not be aware of the nbcon synchronization. This +@@ -3587,6 +3598,8 @@ EXPORT_SYMBOL(register_console); + /* Must be called under console_list_lock(). */ + static int unregister_console_locked(struct console *console) + { ++ bool found_boot_con = false; ++ struct console *c; + int res; + + lockdep_assert_console_list_lock_held(); +@@ -3634,6 +3647,17 @@ static int unregister_console_locked(str + if (console->exit) + res = console->exit(console); + ++ /* ++ * With this console gone, the global flags tracking registered ++ * console types may have changed. Update them. ++ */ ++ for_each_console(c) { ++ if (c->flags & CON_BOOT) ++ found_boot_con = true; ++ } ++ if (!found_boot_con) ++ have_boot_console = found_boot_con; ++ + return res; + } + |