diff options
Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0080-printk-nbcon-Add-sequence-handling.patch | 311 |
1 files changed, 0 insertions, 311 deletions
diff --git a/debian/patches-rt/0080-printk-nbcon-Add-sequence-handling.patch b/debian/patches-rt/0080-printk-nbcon-Add-sequence-handling.patch deleted file mode 100644 index 3988d6124a..0000000000 --- a/debian/patches-rt/0080-printk-nbcon-Add-sequence-handling.patch +++ /dev/null @@ -1,311 +0,0 @@ -From: Thomas Gleixner <tglx@linutronix.de> -Date: Sat, 16 Sep 2023 21:26:05 +0206 -Subject: [PATCH 080/134] printk: nbcon: Add sequence handling -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz - -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 -Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> ---- - include/linux/console.h | 4 + - kernel/printk/internal.h | 7 +++ - kernel/printk/nbcon.c | 101 +++++++++++++++++++++++++++++++++++++++++++++++ - kernel/printk/printk.c | 31 +++++++++++--- - 4 files changed, 136 insertions(+), 7 deletions(-) - ---- a/include/linux/console.h -+++ b/include/linux/console.h -@@ -243,6 +243,7 @@ struct printk_buffers; - * might cause a system freeze when the console - * is used later. - * @pbufs: Pointer to the text buffer for this context -+ * @seq: The sequence number to print for this context - */ - struct nbcon_context { - /* members set by caller */ -@@ -253,6 +254,7 @@ struct nbcon_context { - - /* members set by acquire */ - struct printk_buffers *pbufs; -+ u64 seq; - }; - - /** -@@ -276,6 +278,7 @@ struct nbcon_context { - * @node: hlist node for the console list - * - * @nbcon_state: State for nbcon consoles -+ * @nbcon_seq: Sequence number of the next record for nbcon to print - * @pbufs: Pointer to nbcon private buffer - */ - struct console { -@@ -299,6 +302,7 @@ struct console { - - /* nbcon console specific members */ - atomic_t __private nbcon_state; -+ atomic_long_t __private nbcon_seq; - struct printk_buffers *pbufs; - }; - ---- 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) { } ---- a/kernel/printk/nbcon.c -+++ b/kernel/printk/nbcon.c -@@ -140,6 +140,101 @@ static inline bool nbcon_state_try_cmpxc - return atomic_try_cmpxchg(&ACCESS_PRIVATE(con, nbcon_state), &cur->atom, new->atom); - } - -+#ifdef CONFIG_64BIT -+ -+#define __seq_to_nbcon_seq(seq) (seq) -+#define __nbcon_seq_to_seq(seq) (seq) -+ -+#else /* CONFIG_64BIT */ -+ -+#define __seq_to_nbcon_seq(seq) ((u32)seq) -+ -+static inline u64 __nbcon_seq_to_seq(u32 nbcon_seq) -+{ -+ u64 seq; -+ u64 rb_next_seq; -+ -+ /* -+ * The provided sequence is only the lower 32 bits of the ringbuffer -+ * sequence. It needs to be expanded to 64bit. Get the next sequence -+ * number from the ringbuffer and fold it. -+ * -+ * 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. -+ * -+ * Also the access to the ring buffer is always safe. -+ */ -+ rb_next_seq = prb_next_seq(prb); -+ seq = rb_next_seq - ((u32)rb_next_seq - nbcon_seq); -+ -+ return seq; -+} -+ -+#endif /* CONFIG_64BIT */ -+ -+/** -+ * nbcon_seq_read - Read the current console sequence -+ * @con: Console to read the sequence of -+ * -+ * Return: Sequence number of the next record to print on @con. -+ */ -+u64 nbcon_seq_read(struct console *con) -+{ -+ unsigned long nbcon_seq = atomic_long_read(&ACCESS_PRIVATE(con, nbcon_seq)); -+ -+ return __nbcon_seq_to_seq(nbcon_seq); -+} -+ -+/** -+ * nbcon_seq_force - Force console sequence to a specific value -+ * @con: Console to work on -+ * @seq: Sequence number value to set -+ * -+ * Only to be used during init (before registration) or in extreme situations -+ * (such as panic with CONSOLE_REPLAY_ALL). -+ */ -+void nbcon_seq_force(struct console *con, u64 seq) -+{ -+ /* -+ * If the specified record no longer exists, the oldest available record -+ * is chosen. This is especially important on 32bit systems because only -+ * the lower 32 bits of the sequence number are stored. The upper 32 bits -+ * are derived from the sequence numbers available in the ringbuffer. -+ */ -+ u64 valid_seq = max_t(u64, seq, prb_first_valid_seq(prb)); -+ -+ atomic_long_set(&ACCESS_PRIVATE(con, nbcon_seq), __seq_to_nbcon_seq(valid_seq)); -+ -+ /* Clear con->seq since nbcon consoles use con->nbcon_seq instead. */ -+ con->seq = 0; -+} -+ -+/** -+ * nbcon_seq_try_update - Try to update the console sequence number -+ * @ctxt: Pointer to an acquire context that contains -+ * all information about the acquire mode -+ * @new_seq: The new sequence number to set -+ * -+ * @ctxt->seq is updated to the new value of @con::nbcon_seq (expanded to -+ * the 64bit value). This could be a different value than @new_seq if -+ * nbcon_seq_force() was used or the current context no longer owns the -+ * console. In the later case, it will stop printing anyway. -+ */ -+__maybe_unused -+static void nbcon_seq_try_update(struct nbcon_context *ctxt, u64 new_seq) -+{ -+ unsigned long nbcon_seq = __seq_to_nbcon_seq(ctxt->seq); -+ struct console *con = ctxt->console; -+ -+ if (atomic_long_try_cmpxchg(&ACCESS_PRIVATE(con, nbcon_seq), &nbcon_seq, -+ __seq_to_nbcon_seq(new_seq))) { -+ ctxt->seq = new_seq; -+ } else { -+ ctxt->seq = nbcon_seq_read(con); -+ } -+} -+ - /** - * nbcon_context_try_acquire_direct - Try to acquire directly - * @ctxt: The context of the caller -@@ -510,6 +605,9 @@ static bool nbcon_context_try_acquire(st - else - ctxt->pbufs = con->pbufs; - -+ /* Set the record sequence for this context to print. */ -+ ctxt->seq = nbcon_seq_read(ctxt->console); -+ - return true; - } - -@@ -722,6 +820,8 @@ bool nbcon_alloc(struct console *con) - * - * 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) - { -@@ -730,6 +830,7 @@ void nbcon_init(struct console *con) - /* nbcon_alloc() must have been called and successful! */ - BUG_ON(!con->pbufs); - -+ nbcon_seq_force(con, con->seq); - nbcon_state_set(con, &state); - } - ---- a/kernel/printk/printk.c -+++ b/kernel/printk/printk.c -@@ -494,7 +494,7 @@ static u32 log_buf_len = __LOG_BUF_LEN; - - static struct printk_ringbuffer printk_rb_dynamic; - --static struct printk_ringbuffer *prb = &printk_rb_static; -+struct printk_ringbuffer *prb = &printk_rb_static; - - /* - * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before -@@ -3168,6 +3168,7 @@ void console_flush_on_panic(enum con_flu - - if (mode == CONSOLE_REPLAY_ALL) { - struct console *c; -+ short flags; - int cookie; - u64 seq; - -@@ -3175,11 +3176,17 @@ void console_flush_on_panic(enum con_flu - - cookie = console_srcu_read_lock(); - for_each_console_srcu(c) { -- /* -- * This is an unsynchronized assignment, but the -- * kernel is in "hope and pray" mode anyway. -- */ -- c->seq = seq; -+ flags = console_srcu_read_flags(c); -+ -+ if (flags & CON_NBCON) { -+ nbcon_seq_force(c, seq); -+ } else { -+ /* -+ * This is an unsynchronized assignment. On -+ * panic legacy consoles are only best effort. -+ */ -+ c->seq = seq; -+ } - } - console_srcu_read_unlock(cookie); - } -@@ -3750,6 +3757,7 @@ static bool __pr_flush(struct console *c - struct console *c; - u64 last_diff = 0; - u64 printk_seq; -+ short flags; - int cookie; - u64 diff; - u64 seq; -@@ -3777,6 +3785,9 @@ static bool __pr_flush(struct console *c - for_each_console_srcu(c) { - if (con && con != c) - continue; -+ -+ flags = console_srcu_read_flags(c); -+ - /* - * If consoles are not usable, it cannot be expected - * that they make forward progress, so only increment -@@ -3784,7 +3795,13 @@ static bool __pr_flush(struct console *c - */ - if (!console_is_usable(c)) - continue; -- printk_seq = c->seq; -+ -+ if (flags & CON_NBCON) { -+ printk_seq = nbcon_seq_read(c); -+ } else { -+ printk_seq = c->seq; -+ } -+ - if (printk_seq < seq) - diff += seq - printk_seq; - } |