diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2023-09-16 21:26:05 +0206 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2023-09-18 17:03:45 +0200 |
| commit | ad56ebd1d79b216dc147474fac89a11daf6b10df (patch) | |
| tree | 17c20b002afe4dbdd8b6a1c284ce6a7acc729da9 /kernel/printk/internal.h | |
| parent | 4b08d9e24f50163a8bda0a702b45b06bf841d792 (diff) | |
printk: nbcon: Add sequence handling
Add an atomic_long_t field @nbcon_seq to the console struct to
store the sequence number for nbcon consoles. For nbcon consoles
this will be used instead of the non-atomic @seq field. The new
field allows for safe atomic sequence number updates without
requiring any locking.
On 64bit systems the new field stores the full sequence number.
On 32bit systems the new field stores the lower 32 bits of the
sequence number, which are expanded to 64bit as needed by
folding the values based on the sequence numbers available in
the ringbuffer.
For 32bit systems, having a 32bit representation in the console
is sufficient. If a console ever gets more than 2^31 records
behind the ringbuffer then this is the least of the problems.
Co-developed-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Thomas Gleixner (Intel) <tglx@linutronix.de>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230916192007.608398-7-john.ogness@linutronix.de
Diffstat (limited to 'kernel/printk/internal.h')
| -rw-r--r-- | kernel/printk/internal.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h index f6161cd75d7d..6473f5ae4a18 100644 --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h @@ -4,6 +4,7 @@ */ #include <linux/percpu.h> #include <linux/console.h> +#include "printk_ringbuffer.h" #if defined(CONFIG_PRINTK) && defined(CONFIG_SYSCTL) void __init printk_sysctl_init(void); @@ -42,6 +43,8 @@ enum printk_info_flags { LOG_CONT = 8, /* text is a fragment of a continuation line */ }; +extern struct printk_ringbuffer *prb; + __printf(4, 0) int vprintk_store(int facility, int level, const struct dev_printk_info *dev_info, @@ -69,6 +72,8 @@ void defer_console_output(void); u16 printk_parse_prefix(const char *text, int *level, enum printk_info_flags *flags); +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_free(struct console *con); @@ -88,6 +93,8 @@ void nbcon_free(struct console *con); #define printk_safe_exit_irqrestore(flags) local_irq_restore(flags) static inline bool printk_percpu_data_ready(void) { return false; } +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_free(struct console *con) { } |