58 lines
2.2 KiB
Diff
58 lines
2.2 KiB
Diff
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From: John Ogness <john.ogness@linutronix.de>
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Date: Wed, 4 Sep 2024 14:11:24 +0206
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Subject: [PATCH 42/54] printk: nbcon: Init @nbcon_seq to highest possible
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.11/older/patches-6.11-rt7.tar.xz
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When initializing an nbcon console, have nbcon_alloc() set
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@nbcon_seq to the highest possible sequence number. For all
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practical purposes, this will guarantee that the console
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will have nothing to print until later when @nbcon_seq is
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set to the proper initial printing value.
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This will be particularly important once kthread printing is
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introduced because nbcon_alloc() can create/start the kthread
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before the desired initial sequence number is known.
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Signed-off-by: John Ogness <john.ogness@linutronix.de>
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Reviewed-by: Petr Mladek <pmladek@suse.com>
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Link: https://lore.kernel.org/r/20240904120536.115780-6-john.ogness@linutronix.de
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Signed-off-by: Petr Mladek <pmladek@suse.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/printk/nbcon.c | 8 +++++++-
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kernel/printk/printk_ringbuffer.h | 2 ++
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2 files changed, 9 insertions(+), 1 deletion(-)
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--- a/kernel/printk/nbcon.c
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+++ b/kernel/printk/nbcon.c
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@@ -1397,7 +1397,13 @@ bool nbcon_alloc(struct console *con)
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struct nbcon_state state = { };
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nbcon_state_set(con, &state);
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- atomic_long_set(&ACCESS_PRIVATE(con, nbcon_seq), 0);
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+
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+ /*
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+ * Initialize @nbcon_seq to the highest possible sequence number so
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+ * that practically speaking it will have nothing to print until a
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+ * desired initial sequence number has been set via nbcon_seq_force().
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+ */
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+ atomic_long_set(&ACCESS_PRIVATE(con, nbcon_seq), ULSEQ_MAX(prb));
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if (con->flags & CON_BOOT) {
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/*
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--- a/kernel/printk/printk_ringbuffer.h
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+++ b/kernel/printk/printk_ringbuffer.h
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@@ -404,10 +404,12 @@ u64 prb_next_reserve_seq(struct printk_r
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#define __u64seq_to_ulseq(u64seq) (u64seq)
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#define __ulseq_to_u64seq(rb, ulseq) (ulseq)
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+#define ULSEQ_MAX(rb) (-1)
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#else /* CONFIG_64BIT */
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#define __u64seq_to_ulseq(u64seq) ((u32)u64seq)
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+#define ULSEQ_MAX(rb) __u64seq_to_ulseq(prb_first_seq(rb) + 0x80000000UL)
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static inline u64 __ulseq_to_u64seq(struct printk_ringbuffer *rb, u32 ulseq)
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{
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