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linux/debian/patches-rt/0042-printk-nbcon-Init-nbcon_seq-to-highest-possible.patch
Konstantin Demin c3d09a3e94 initial commit
imported from https://salsa.debian.org/kernel-team/linux.git
commit 9d5cc9d9d6501d7f1dd7e194d4b245bd0b6c6a22
version 6.11.4-1
2024-10-23 12:12:30 +03:00

58 lines
2.2 KiB
Diff

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