diff options
Diffstat (limited to 'debian/patches-rt/0002-printk-Properly-deal-with-nbcon-consoles-on-seq-init.patch')
| -rw-r--r-- | debian/patches-rt/0002-printk-Properly-deal-with-nbcon-consoles-on-seq-init.patch | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/debian/patches-rt/0002-printk-Properly-deal-with-nbcon-consoles-on-seq-init.patch b/debian/patches-rt/0002-printk-Properly-deal-with-nbcon-consoles-on-seq-init.patch new file mode 100644 index 0000000000..e42d83f140 --- /dev/null +++ b/debian/patches-rt/0002-printk-Properly-deal-with-nbcon-consoles-on-seq-init.patch @@ -0,0 +1,190 @@ +From: Petr Mladek <pmladek@suse.com> +Date: Wed, 22 Nov 2023 11:23:43 +0000 +Subject: [PATCH 02/46] printk: Properly deal with nbcon consoles on seq init +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.9/older/patches-6.9-rt5.tar.xz + +If a non-boot console is registering and boot consoles exist, +the consoles are flushed before being unregistered. This allows +the non-boot console to continue where the boot console left +off. + +If for whatever reason flushing fails, the lowest seq found from +any of the enabled boot consoles is used. Until now con->seq was +checked. However, if it is an nbcon boot console, the function +nbcon_seq_read() must be used to read seq because con->seq is +not updated for nbcon consoles. + +Check if it is an nbcon boot console and if so call +nbcon_seq_read() to read seq. + +Also, avoid usage of con->seq as temporary storage of the +starting record. Instead, rename console_init_seq() to +get_init_console_seq() and just return the value. For nbcon +consoles set the sequence via nbcon_init(), for legacy consoles +set con->seq. + +The cleaned design should make sure that the value stays and is +set before the printing kthread is created. + +Signed-off-by: Petr Mladek <pmladek@suse.com> +Reviewed-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + kernel/printk/internal.h | 4 ++-- + kernel/printk/nbcon.c | 10 +++------- + kernel/printk/printk.c | 41 +++++++++++++++++++++++++++++------------ + 3 files changed, 34 insertions(+), 21 deletions(-) + +--- a/kernel/printk/internal.h ++++ b/kernel/printk/internal.h +@@ -75,7 +75,7 @@ u16 printk_parse_prefix(const char *text + u64 nbcon_seq_read(struct console *con); + void nbcon_seq_force(struct console *con, u64 seq); + bool nbcon_alloc(struct console *con); +-void nbcon_init(struct console *con); ++void nbcon_init(struct console *con, u64 init_seq); + void nbcon_free(struct console *con); + + #else +@@ -96,7 +96,7 @@ static inline bool printk_percpu_data_re + static inline u64 nbcon_seq_read(struct console *con) { return 0; } + static inline void nbcon_seq_force(struct console *con, u64 seq) { } + static inline bool nbcon_alloc(struct console *con) { return false; } +-static inline void nbcon_init(struct console *con) { } ++static inline void nbcon_init(struct console *con, u64 init_seq) { } + static inline void nbcon_free(struct console *con) { } + + #endif /* CONFIG_PRINTK */ +--- a/kernel/printk/nbcon.c ++++ b/kernel/printk/nbcon.c +@@ -172,9 +172,6 @@ void nbcon_seq_force(struct console *con + u64 valid_seq = max_t(u64, seq, prb_first_valid_seq(prb)); + + atomic_long_set(&ACCESS_PRIVATE(con, nbcon_seq), __u64seq_to_ulseq(valid_seq)); +- +- /* Clear con->seq since nbcon consoles use con->nbcon_seq instead. */ +- con->seq = 0; + } + + /** +@@ -961,20 +958,19 @@ bool nbcon_alloc(struct console *con) + /** + * nbcon_init - Initialize the nbcon console specific data + * @con: Console to initialize ++ * @init_seq: Sequence number of the first record to be emitted + * + * nbcon_alloc() *must* be called and succeed before this function + * is called. +- * +- * This function expects that the legacy @con->seq has been set. + */ +-void nbcon_init(struct console *con) ++void nbcon_init(struct console *con, u64 init_seq) + { + struct nbcon_state state = { }; + + /* nbcon_alloc() must have been called and successful! */ + BUG_ON(!con->pbufs); + +- nbcon_seq_force(con, con->seq); ++ nbcon_seq_force(con, init_seq); + nbcon_state_set(con, &state); + } + +--- a/kernel/printk/printk.c ++++ b/kernel/printk/printk.c +@@ -3363,19 +3363,21 @@ static void try_enable_default_console(s + newcon->flags |= CON_CONSDEV; + } + +-static void console_init_seq(struct console *newcon, bool bootcon_registered) ++/* Return the starting sequence number for a newly registered console. */ ++static u64 get_init_console_seq(struct console *newcon, bool bootcon_registered) + { + struct console *con; + bool handover; ++ u64 init_seq; + + if (newcon->flags & (CON_PRINTBUFFER | CON_BOOT)) { + /* Get a consistent copy of @syslog_seq. */ + mutex_lock(&syslog_lock); +- newcon->seq = syslog_seq; ++ init_seq = syslog_seq; + mutex_unlock(&syslog_lock); + } else { + /* Begin with next message added to ringbuffer. */ +- newcon->seq = prb_next_seq(prb); ++ init_seq = prb_next_seq(prb); + + /* + * If any enabled boot consoles are due to be unregistered +@@ -3396,7 +3398,7 @@ static void console_init_seq(struct cons + * Flush all consoles and set the console to start at + * the next unprinted sequence number. + */ +- if (!console_flush_all(true, &newcon->seq, &handover)) { ++ if (!console_flush_all(true, &init_seq, &handover)) { + /* + * Flushing failed. Just choose the lowest + * sequence of the enabled boot consoles. +@@ -3409,19 +3411,30 @@ static void console_init_seq(struct cons + if (handover) + console_lock(); + +- newcon->seq = prb_next_seq(prb); ++ init_seq = prb_next_seq(prb); + for_each_console(con) { +- if ((con->flags & CON_BOOT) && +- (con->flags & CON_ENABLED) && +- con->seq < newcon->seq) { +- newcon->seq = con->seq; ++ u64 seq; ++ ++ if (!(con->flags & CON_BOOT) || ++ !(con->flags & CON_ENABLED)) { ++ continue; + } ++ ++ if (con->flags & CON_NBCON) ++ seq = nbcon_seq_read(con); ++ else ++ seq = con->seq; ++ ++ if (seq < init_seq) ++ init_seq = seq; + } + } + + console_unlock(); + } + } ++ ++ return init_seq; + } + + #define console_first() \ +@@ -3453,6 +3466,7 @@ void register_console(struct console *ne + struct console *con; + bool bootcon_registered = false; + bool realcon_registered = false; ++ u64 init_seq; + int err; + + console_list_lock(); +@@ -3530,10 +3544,13 @@ void register_console(struct console *ne + } + + newcon->dropped = 0; +- console_init_seq(newcon, bootcon_registered); ++ init_seq = get_init_console_seq(newcon, bootcon_registered); + +- if (newcon->flags & CON_NBCON) +- nbcon_init(newcon); ++ if (newcon->flags & CON_NBCON) { ++ nbcon_init(newcon, init_seq); ++ } else { ++ newcon->seq = init_seq; ++ } + + /* + * Put this console in the list - keep the |