mirror of
https://github.com/OpenVoiceOS/OpenVoiceOS
synced 2025-02-12 18:00:45 +01:00
273 lines
9.3 KiB
Diff
273 lines
9.3 KiB
Diff
From 2cacec8fd401821eda87a80dfbaa8453ac4252b8 Mon Sep 17 00:00:00 2001
|
|
From: Thomas Gleixner <tglx@linutronix.de>
|
|
Date: Sat, 16 Sep 2023 21:26:06 +0206
|
|
Subject: [PATCH 108/195] printk: nbcon: Add emit function and callback
|
|
function for atomic printing
|
|
|
|
Implement an emit function for nbcon consoles to output printk
|
|
messages. It utilizes the lockless printk_get_next_message() and
|
|
console_prepend_dropped() functions to retrieve/build the output
|
|
message. The emit function includes the required safety points to
|
|
check for handover/takeover and calls a new write_atomic callback
|
|
of the console driver to output the message. It also includes
|
|
proper handling for updating the nbcon console sequence number.
|
|
|
|
A new nbcon_write_context struct is introduced. This is provided
|
|
to the write_atomic callback and includes only the information
|
|
necessary for performing atomic writes.
|
|
|
|
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>
|
|
Reviewed-by: Petr Mladek <pmladek@suse.com>
|
|
Signed-off-by: Petr Mladek <pmladek@suse.com>
|
|
Link: https://lore.kernel.org/r/20230916192007.608398-8-john.ogness@linutronix.de
|
|
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
---
|
|
include/linux/console.h | 21 ++++++++
|
|
kernel/printk/internal.h | 6 +++
|
|
kernel/printk/nbcon.c | 106 ++++++++++++++++++++++++++++++++++++++-
|
|
kernel/printk/printk.c | 9 ++--
|
|
4 files changed, 134 insertions(+), 8 deletions(-)
|
|
|
|
diff --git a/include/linux/console.h b/include/linux/console.h
|
|
index 20cd486b76ad..14563dcb34b1 100644
|
|
--- a/include/linux/console.h
|
|
+++ b/include/linux/console.h
|
|
@@ -242,6 +242,7 @@ struct printk_buffers;
|
|
* be used only with NBCON_PRIO_PANIC @prio. It
|
|
* might cause a system freeze when the console
|
|
* is used later.
|
|
+ * @backlog: Ringbuffer has pending records
|
|
* @pbufs: Pointer to the text buffer for this context
|
|
* @seq: The sequence number to print for this context
|
|
*/
|
|
@@ -252,11 +253,28 @@ struct nbcon_context {
|
|
enum nbcon_prio prio;
|
|
unsigned int allow_unsafe_takeover : 1;
|
|
|
|
+ /* members set by emit */
|
|
+ unsigned int backlog : 1;
|
|
+
|
|
/* members set by acquire */
|
|
struct printk_buffers *pbufs;
|
|
u64 seq;
|
|
};
|
|
|
|
+/**
|
|
+ * struct nbcon_write_context - Context handed to the nbcon write callbacks
|
|
+ * @ctxt: The core console context
|
|
+ * @outbuf: Pointer to the text buffer for output
|
|
+ * @len: Length to write
|
|
+ * @unsafe_takeover: If a hostile takeover in an unsafe state has occurred
|
|
+ */
|
|
+struct nbcon_write_context {
|
|
+ struct nbcon_context __private ctxt;
|
|
+ char *outbuf;
|
|
+ unsigned int len;
|
|
+ bool unsafe_takeover;
|
|
+};
|
|
+
|
|
/**
|
|
* struct console - The console descriptor structure
|
|
* @name: The name of the console driver
|
|
@@ -277,6 +295,7 @@ struct nbcon_context {
|
|
* @data: Driver private data
|
|
* @node: hlist node for the console list
|
|
*
|
|
+ * @write_atomic: Write callback for atomic context
|
|
* @nbcon_state: State for nbcon consoles
|
|
* @nbcon_seq: Sequence number of the next record for nbcon to print
|
|
* @pbufs: Pointer to nbcon private buffer
|
|
@@ -301,6 +320,8 @@ struct console {
|
|
struct hlist_node node;
|
|
|
|
/* nbcon console specific members */
|
|
+ bool (*write_atomic)(struct console *con,
|
|
+ struct nbcon_write_context *wctxt);
|
|
atomic_t __private nbcon_state;
|
|
atomic_long_t __private nbcon_seq;
|
|
struct printk_buffers *pbufs;
|
|
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
|
|
index 6473f5ae4a18..6c2afee5ef62 100644
|
|
--- a/kernel/printk/internal.h
|
|
+++ b/kernel/printk/internal.h
|
|
@@ -130,3 +130,9 @@ struct printk_message {
|
|
};
|
|
|
|
bool other_cpu_in_panic(void);
|
|
+bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
|
|
+ bool is_extended, bool may_supress);
|
|
+
|
|
+#ifdef CONFIG_PRINTK
|
|
+void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped);
|
|
+#endif
|
|
diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c
|
|
index e076096b31c0..6e05d263fd22 100644
|
|
--- a/kernel/printk/nbcon.c
|
|
+++ b/kernel/printk/nbcon.c
|
|
@@ -221,7 +221,6 @@ void nbcon_seq_force(struct console *con, u64 seq)
|
|
* 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);
|
|
@@ -755,7 +754,6 @@ static bool nbcon_context_can_proceed(struct nbcon_context *ctxt, struct nbcon_s
|
|
*
|
|
* Internal helper to avoid duplicated code.
|
|
*/
|
|
-__maybe_unused
|
|
static bool __nbcon_context_update_unsafe(struct nbcon_context *ctxt, bool unsafe)
|
|
{
|
|
struct console *con = ctxt->console;
|
|
@@ -784,6 +782,110 @@ static bool __nbcon_context_update_unsafe(struct nbcon_context *ctxt, bool unsaf
|
|
return nbcon_context_can_proceed(ctxt, &cur);
|
|
}
|
|
|
|
+/**
|
|
+ * nbcon_emit_next_record - Emit a record in the acquired context
|
|
+ * @wctxt: The write context that will be handed to the write function
|
|
+ *
|
|
+ * Return: True if this context still owns the console. False if
|
|
+ * ownership was handed over or taken.
|
|
+ *
|
|
+ * When this function returns false then the calling context no longer owns
|
|
+ * the console and is no longer allowed to go forward. In this case it must
|
|
+ * back out immediately and carefully. The buffer content is also no longer
|
|
+ * trusted since it no longer belongs to the calling context. If the caller
|
|
+ * wants to do more it must reacquire the console first.
|
|
+ *
|
|
+ * When true is returned, @wctxt->ctxt.backlog indicates whether there are
|
|
+ * still records pending in the ringbuffer,
|
|
+ */
|
|
+__maybe_unused
|
|
+static bool nbcon_emit_next_record(struct nbcon_write_context *wctxt)
|
|
+{
|
|
+ struct nbcon_context *ctxt = &ACCESS_PRIVATE(wctxt, ctxt);
|
|
+ struct console *con = ctxt->console;
|
|
+ bool is_extended = console_srcu_read_flags(con) & CON_EXTENDED;
|
|
+ struct printk_message pmsg = {
|
|
+ .pbufs = ctxt->pbufs,
|
|
+ };
|
|
+ unsigned long con_dropped;
|
|
+ struct nbcon_state cur;
|
|
+ unsigned long dropped;
|
|
+ bool done;
|
|
+
|
|
+ /*
|
|
+ * The printk buffers are filled within an unsafe section. This
|
|
+ * prevents NBCON_PRIO_NORMAL and NBCON_PRIO_EMERGENCY from
|
|
+ * clobbering each other.
|
|
+ */
|
|
+
|
|
+ if (!nbcon_context_enter_unsafe(ctxt))
|
|
+ return false;
|
|
+
|
|
+ ctxt->backlog = printk_get_next_message(&pmsg, ctxt->seq, is_extended, true);
|
|
+ if (!ctxt->backlog)
|
|
+ return nbcon_context_exit_unsafe(ctxt);
|
|
+
|
|
+ /*
|
|
+ * @con->dropped is not protected in case of an unsafe hostile
|
|
+ * takeover. In that situation the update can be racy so
|
|
+ * annotate it accordingly.
|
|
+ */
|
|
+ con_dropped = data_race(READ_ONCE(con->dropped));
|
|
+
|
|
+ dropped = con_dropped + pmsg.dropped;
|
|
+ if (dropped && !is_extended)
|
|
+ console_prepend_dropped(&pmsg, dropped);
|
|
+
|
|
+ if (!nbcon_context_exit_unsafe(ctxt))
|
|
+ return false;
|
|
+
|
|
+ /* For skipped records just update seq/dropped in @con. */
|
|
+ if (pmsg.outbuf_len == 0)
|
|
+ goto update_con;
|
|
+
|
|
+ /* Initialize the write context for driver callbacks. */
|
|
+ wctxt->outbuf = &pmsg.pbufs->outbuf[0];
|
|
+ wctxt->len = pmsg.outbuf_len;
|
|
+ nbcon_state_read(con, &cur);
|
|
+ wctxt->unsafe_takeover = cur.unsafe_takeover;
|
|
+
|
|
+ if (con->write_atomic) {
|
|
+ done = con->write_atomic(con, wctxt);
|
|
+ } else {
|
|
+ nbcon_context_release(ctxt);
|
|
+ WARN_ON_ONCE(1);
|
|
+ done = false;
|
|
+ }
|
|
+
|
|
+ /* If not done, the emit was aborted. */
|
|
+ if (!done)
|
|
+ return false;
|
|
+
|
|
+ /*
|
|
+ * Since any dropped message was successfully output, reset the
|
|
+ * dropped count for the console.
|
|
+ */
|
|
+ dropped = 0;
|
|
+update_con:
|
|
+ /*
|
|
+ * The dropped count and the sequence number are updated within an
|
|
+ * unsafe section. This limits update races to the panic context and
|
|
+ * allows the panic context to win.
|
|
+ */
|
|
+
|
|
+ if (!nbcon_context_enter_unsafe(ctxt))
|
|
+ return false;
|
|
+
|
|
+ if (dropped != con_dropped) {
|
|
+ /* Counterpart to the READ_ONCE() above. */
|
|
+ WRITE_ONCE(con->dropped, dropped);
|
|
+ }
|
|
+
|
|
+ nbcon_seq_try_update(ctxt, pmsg.seq + 1);
|
|
+
|
|
+ return nbcon_context_exit_unsafe(ctxt);
|
|
+}
|
|
+
|
|
/**
|
|
* nbcon_alloc - Allocate buffers needed by the nbcon console
|
|
* @con: Console to allocate buffers for
|
|
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
|
|
index de54e4942aa5..1638eaf3708a 100644
|
|
--- a/kernel/printk/printk.c
|
|
+++ b/kernel/printk/printk.c
|
|
@@ -698,9 +698,6 @@ static ssize_t msg_print_ext_body(char *buf, size_t size,
|
|
return len;
|
|
}
|
|
|
|
-static bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
|
|
- bool is_extended, bool may_supress);
|
|
-
|
|
/* /dev/kmsg - userspace message inject/listen interface */
|
|
struct devkmsg_user {
|
|
atomic64_t seq;
|
|
@@ -2733,7 +2730,7 @@ static void __console_unlock(void)
|
|
* If @pmsg->pbufs->outbuf is modified, @pmsg->outbuf_len is updated.
|
|
*/
|
|
#ifdef CONFIG_PRINTK
|
|
-static void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
|
|
+void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
|
|
{
|
|
struct printk_buffers *pbufs = pmsg->pbufs;
|
|
const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf);
|
|
@@ -2787,8 +2784,8 @@ static void console_prepend_dropped(struct printk_message *pmsg, unsigned long d
|
|
* of @pmsg are valid. (See the documentation of struct printk_message
|
|
* for information about the @pmsg fields.)
|
|
*/
|
|
-static bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
|
|
- bool is_extended, bool may_suppress)
|
|
+bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
|
|
+ bool is_extended, bool may_suppress)
|
|
{
|
|
static int panic_console_dropped;
|
|
|
|
--
|
|
2.43.0
|
|
|