diff options
Diffstat (limited to 'debian/patches-rt/0025-printk-nbcon-Implement-emergency-sections.patch')
| -rw-r--r-- | debian/patches-rt/0025-printk-nbcon-Implement-emergency-sections.patch | 80 |
1 files changed, 64 insertions, 16 deletions
diff --git a/debian/patches-rt/0025-printk-nbcon-Implement-emergency-sections.patch b/debian/patches-rt/0025-printk-nbcon-Implement-emergency-sections.patch index 44327c280a..7370f8513f 100644 --- a/debian/patches-rt/0025-printk-nbcon-Implement-emergency-sections.patch +++ b/debian/patches-rt/0025-printk-nbcon-Implement-emergency-sections.patch @@ -1,7 +1,7 @@ From: Thomas Gleixner <tglx@linutronix.de> Date: Mon, 11 Sep 2023 15:21:57 +0000 -Subject: [PATCH 25/46] printk: nbcon: Implement emergency sections -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.9/older/patches-6.9-rt5.tar.xz +Subject: [PATCH 25/48] printk: nbcon: Implement emergency sections +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.10/older/patches-6.10.2-rt14.tar.xz In emergency situations (something has gone wrong but the system continues to operate), usually important information @@ -26,8 +26,8 @@ Do not print if the current CPU is in an emergency state. When exiting all emergency nesting, flush nbcon consoles directly using their atomic callback. Legacy consoles are -triggered for flushing via irq_work because it is not known -if the context was safe for a trylock on the console lock. +flushed directly if safe, otherwise they are triggered for +flushing via irq_work. Note that the emergency state is not system-wide. While one CPU is in an emergency state, another CPU may continue to print @@ -36,13 +36,15 @@ console messages. 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> +Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- - include/linux/console.h | 6 ++ - kernel/printk/internal.h | 11 ++++ - kernel/printk/nbcon.c | 116 +++++++++++++++++++++++++++++++++++++++++++++++ - kernel/printk/printk.c | 25 +++++----- - 4 files changed, 146 insertions(+), 12 deletions(-) + include/linux/console.h | 6 ++ + kernel/printk/internal.h | 13 ++++ + kernel/printk/nbcon.c | 126 ++++++++++++++++++++++++++++++++++++++++++++ + kernel/printk/printk.c | 25 ++++---- + kernel/printk/printk_safe.c | 11 +++ + 5 files changed, 168 insertions(+), 13 deletions(-) --- a/include/linux/console.h +++ b/include/linux/console.h @@ -65,7 +67,16 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> static inline bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) { return false; } --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h -@@ -153,6 +153,17 @@ static inline bool console_is_usable(str +@@ -76,6 +76,8 @@ bool printk_percpu_data_ready(void); + + void defer_console_output(void); + ++bool is_printk_deferred(void); ++ + u16 printk_parse_prefix(const char *text, int *level, + enum printk_info_flags *flags); + void console_lock_spinning_enable(void); +@@ -153,6 +155,17 @@ static inline bool console_is_usable(str #endif /* CONFIG_PRINTK */ @@ -131,7 +142,7 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> return NBCON_PRIO_NORMAL; } -@@ -1200,6 +1229,93 @@ void nbcon_atomic_flush_unsafe(void) +@@ -1207,6 +1236,103 @@ void nbcon_atomic_flush_unsafe(void) } /** @@ -182,13 +193,23 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> + */ + if (*cpu_emergency_nesting == 1) { + nbcon_atomic_flush_pending(); ++ ++ /* ++ * Safely attempt to flush the legacy consoles in this ++ * context. Otherwise an irq_work context is triggered ++ * to handle it. ++ */ + do_trigger_flush = true; ++ if (printing_via_unlock && !is_printk_deferred()) { ++ if (console_trylock()) { ++ do_trigger_flush = false; ++ console_unlock(); ++ } ++ } + } + -+ (*cpu_emergency_nesting)--; -+ -+ if (WARN_ON_ONCE(*cpu_emergency_nesting < 0)) -+ *cpu_emergency_nesting = 0; ++ if (!WARN_ON_ONCE(*cpu_emergency_nesting == 0)) ++ (*cpu_emergency_nesting)--; + + preempt_enable(); + @@ -215,7 +236,7 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> + + nbcon_atomic_flush_pending(); + -+ if (printing_via_unlock && !in_nmi()) { ++ if (printing_via_unlock && !is_printk_deferred()) { + if (console_trylock()) + console_unlock(); + } @@ -281,3 +302,30 @@ Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> preempt_enable(); } +--- a/kernel/printk/printk_safe.c ++++ b/kernel/printk/printk_safe.c +@@ -38,6 +38,15 @@ void __printk_deferred_exit(void) + __printk_safe_exit(); + } + ++bool is_printk_deferred(void) ++{ ++ /* ++ * The per-CPU variable @printk_context can be read safely in any ++ * context. The CPU migration always disabled when set. ++ */ ++ return (this_cpu_read(printk_context) || in_nmi()); ++} ++ + asmlinkage int vprintk(const char *fmt, va_list args) + { + #ifdef CONFIG_KGDB_KDB +@@ -50,7 +59,7 @@ asmlinkage int vprintk(const char *fmt, + * Use the main logbuf even in NMI. But avoid calling console + * drivers that might have their own locks. + */ +- if (this_cpu_read(printk_context) || in_nmi()) ++ if (is_printk_deferred()) + return vprintk_deferred(fmt, args); + + /* No obstacles. */ |