80 lines
2.6 KiB
Diff
80 lines
2.6 KiB
Diff
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From: John Ogness <john.ogness@linutronix.de>
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Date: Tue, 20 Aug 2024 08:35:50 +0206
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Subject: [PATCH 24/54] printk: nbcon: Flush new records on device_release()
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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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There may be new records that were added while a driver was
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holding the nbcon context for non-printing purposes. These
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new records must be flushed by the nbcon_device_release()
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context because no other context will do it.
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If boot consoles are registered, the legacy loop is used
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(either direct or per irq_work) to handle the flushing.
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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/20240820063001.36405-25-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/internal.h | 2 ++
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kernel/printk/nbcon.c | 20 ++++++++++++++++++++
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kernel/printk/printk.c | 2 +-
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3 files changed, 23 insertions(+), 1 deletion(-)
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--- a/kernel/printk/internal.h
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+++ b/kernel/printk/internal.h
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@@ -153,6 +153,8 @@ static inline bool console_is_usable(str
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#endif /* CONFIG_PRINTK */
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+extern bool have_boot_console;
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+
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extern struct printk_buffers printk_shared_pbufs;
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/**
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--- a/kernel/printk/nbcon.c
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+++ b/kernel/printk/nbcon.c
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@@ -1326,10 +1326,30 @@ EXPORT_SYMBOL_GPL(nbcon_device_try_acqui
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void nbcon_device_release(struct console *con)
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{
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struct nbcon_context *ctxt = &ACCESS_PRIVATE(con, nbcon_device_ctxt);
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+ int cookie;
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if (!nbcon_context_exit_unsafe(ctxt))
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return;
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nbcon_context_release(ctxt);
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+
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+ /*
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+ * This context must flush any new records added while the console
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+ * was locked. The console_srcu_read_lock must be taken to ensure
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+ * the console is usable throughout flushing.
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+ */
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+ cookie = console_srcu_read_lock();
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+ if (console_is_usable(con, console_srcu_read_flags(con)) &&
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+ prb_read_valid(prb, nbcon_seq_read(con), NULL)) {
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+ if (!have_boot_console) {
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+ __nbcon_atomic_flush_pending_con(con, prb_next_reserve_seq(prb));
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+ } else if (!is_printk_legacy_deferred()) {
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+ if (console_trylock())
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+ console_unlock();
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+ } else {
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+ printk_trigger_flush();
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+ }
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+ }
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+ console_srcu_read_unlock(cookie);
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}
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EXPORT_SYMBOL_GPL(nbcon_device_release);
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--- a/kernel/printk/printk.c
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+++ b/kernel/printk/printk.c
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@@ -469,7 +469,7 @@ static DEFINE_MUTEX(syslog_lock);
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* the console lock. This is because boot consoles and nbcon consoles may
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* have mapped the same hardware.
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*/
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-static bool have_boot_console;
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+bool have_boot_console;
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#ifdef CONFIG_PRINTK
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DECLARE_WAIT_QUEUE_HEAD(log_wait);
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