183 lines
6.4 KiB
Diff
183 lines
6.4 KiB
Diff
From d9b5edbbf16c03ead8cdce023e65056a7b8145b2 Mon Sep 17 00:00:00 2001
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From: John Ogness <john.ogness@linutronix.de>
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Date: Tue, 19 Sep 2023 14:33:27 +0000
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Subject: [PATCH 136/196] printk: nbcon: Use nbcon consoles in
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console_flush_all()
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Allow nbcon consoles to print messages in the printk() caller
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context by integrating them into console_flush_all(). The
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write_atomic() callback is used for printing.
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Provide nbcon_console_emit_next_record(), which acts as the
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nbcon variant of console_emit_next_record(). Call this variant
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within console_flush_all() for nbcon consoles. Since nbcon
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consoles use their own @nbcon_seq variable to track the next
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record to print, this also must be appropriately handled.
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Signed-off-by: John Ogness <john.ogness@linutronix.de>
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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 | 5 ++++
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kernel/printk/nbcon.c | 50 ++++++++++++++++++++++++++++++++++++++++
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kernel/printk/printk.c | 19 +++++++++++----
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3 files changed, 69 insertions(+), 5 deletions(-)
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diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
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index d6cb8d2be944..e7cdea097cec 100644
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--- a/kernel/printk/internal.h
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+++ b/kernel/printk/internal.h
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@@ -71,6 +71,8 @@ void defer_console_output(void);
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u16 printk_parse_prefix(const char *text, int *level,
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enum printk_info_flags *flags);
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+void console_lock_spinning_enable(void);
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+int console_lock_spinning_disable_and_check(int cookie);
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u64 nbcon_seq_read(struct console *con);
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void nbcon_seq_force(struct console *con, u64 seq);
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@@ -78,6 +80,7 @@ bool nbcon_alloc(struct console *con);
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void nbcon_init(struct console *con);
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void nbcon_free(struct console *con);
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void nbcon_atomic_flush_all(void);
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+bool nbcon_atomic_emit_next_record(struct console *con, bool *handover, int cookie);
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/*
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* Check if the given console is currently capable and allowed to print
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@@ -133,6 +136,8 @@ static inline bool nbcon_alloc(struct console *con) { return false; }
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static inline void nbcon_init(struct console *con) { }
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static inline void nbcon_free(struct console *con) { }
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static inline void nbcon_atomic_flush_all(void) { }
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+static inline bool nbcon_atomic_emit_next_record(struct console *con, bool *handover,
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+ int cookie) { return false; }
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static inline bool console_is_usable(struct console *con, short flags) { return false; }
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diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
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index d0780168e319..c17cf3ea6153 100644
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--- a/kernel/printk/nbcon.c
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+++ b/kernel/printk/nbcon.c
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@@ -532,6 +532,7 @@ static struct printk_buffers panic_nbcon_pbufs;
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* nbcon_context_try_acquire - Try to acquire nbcon console
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* @ctxt: The context of the caller
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*
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+ * Context: Any context which could not be migrated to another CPU.
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* Return: True if the console was acquired. False otherwise.
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*
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* If the caller allowed an unsafe hostile takeover, on success the
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@@ -960,6 +961,55 @@ static bool nbcon_atomic_emit_one(struct nbcon_write_context *wctxt)
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return ctxt->backlog;
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}
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+/**
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+ * nbcon_atomic_emit_next_record - Print one record for an nbcon console
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+ * using the write_atomic() callback
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+ * @con: The console to print on
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+ * @handover: Will be set to true if a printk waiter has taken over the
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+ * console_lock, in which case the caller is no longer holding
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+ * both the console_lock and the SRCU read lock. Otherwise it
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+ * is set to false.
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+ * @cookie: The cookie from the SRCU read lock.
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+ *
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+ * Context: Any context which could not be migrated to another CPU.
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+ * Return: True if a record could be printed, otherwise false.
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+ *
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+ * This function is meant to be called by console_flush_all() to print records
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+ * on nbcon consoles using the write_atomic() callback. Essentially it is the
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+ * nbcon version of console_emit_next_record().
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+ */
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+bool nbcon_atomic_emit_next_record(struct console *con, bool *handover, int cookie)
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+{
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+ struct nbcon_write_context wctxt = { };
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+ struct nbcon_context *ctxt = &ACCESS_PRIVATE(&wctxt, ctxt);
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+ unsigned long driver_flags;
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+ bool progress = false;
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+ unsigned long flags;
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+
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+ *handover = false;
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+
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+ /* Use the same locking order as console_emit_next_record(). */
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+ printk_safe_enter_irqsave(flags);
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+ console_lock_spinning_enable();
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+ stop_critical_timings();
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+
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+ con->driver_enter(con, &driver_flags);
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+ cant_migrate();
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+
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+ ctxt->console = con;
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+ ctxt->prio = NBCON_PRIO_NORMAL;
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+
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+ progress = nbcon_atomic_emit_one(&wctxt);
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+
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+ con->driver_exit(con, driver_flags);
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+
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+ start_critical_timings();
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+ *handover = console_lock_spinning_disable_and_check(cookie);
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+ printk_safe_exit_irqrestore(flags);
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+
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+ return progress;
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+}
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+
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/**
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* __nbcon_atomic_flush_all - Flush all nbcon consoles using their
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* write_atomic() callback
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diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
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index 1ad6d6d8ad2e..8a023a6db7c9 100644
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--- a/kernel/printk/printk.c
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+++ b/kernel/printk/printk.c
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@@ -1872,7 +1872,7 @@ static bool console_waiter;
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* there may be a waiter spinning (like a spinlock). Also it must be
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* ready to hand over the lock at the end of the section.
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*/
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-static void console_lock_spinning_enable(void)
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+void console_lock_spinning_enable(void)
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{
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/*
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* Do not use spinning in panic(). The panic CPU wants to keep the lock.
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@@ -1911,7 +1911,7 @@ static void console_lock_spinning_enable(void)
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*
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* Return: 1 if the lock rights were passed, 0 otherwise.
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*/
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-static int console_lock_spinning_disable_and_check(int cookie)
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+int console_lock_spinning_disable_and_check(int cookie)
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{
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int waiter;
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@@ -2949,13 +2949,22 @@ static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handove
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cookie = console_srcu_read_lock();
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for_each_console_srcu(con) {
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short flags = console_srcu_read_flags(con);
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+ u64 printk_seq;
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bool progress;
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if (!console_is_usable(con, flags))
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continue;
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any_usable = true;
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- progress = console_emit_next_record(con, handover, cookie);
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+ if (flags & CON_NBCON) {
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+ progress = nbcon_atomic_emit_next_record(con, handover, cookie);
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+
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+ printk_seq = nbcon_seq_read(con);
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+ } else {
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+ progress = console_emit_next_record(con, handover, cookie);
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+
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+ printk_seq = con->seq;
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+ }
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/*
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* If a handover has occurred, the SRCU read lock
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@@ -2965,8 +2974,8 @@ static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handove
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return false;
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/* Track the next of the highest seq flushed. */
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- if (con->seq > *next_seq)
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- *next_seq = con->seq;
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+ if (printk_seq > *next_seq)
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+ *next_seq = printk_seq;
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if (!progress)
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continue;
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--
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2.43.2
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