summaryrefslogtreecommitdiffstats
path: root/debian/patches-rt/0081-printk-nbcon-Add-emit-function-and-callback-function.patch
diff options
context:
space:
mode:
Diffstat (limited to 'debian/patches-rt/0081-printk-nbcon-Add-emit-function-and-callback-function.patch')
-rw-r--r--debian/patches-rt/0081-printk-nbcon-Add-emit-function-and-callback-function.patch262
1 files changed, 0 insertions, 262 deletions
diff --git a/debian/patches-rt/0081-printk-nbcon-Add-emit-function-and-callback-function.patch b/debian/patches-rt/0081-printk-nbcon-Add-emit-function-and-callback-function.patch
deleted file mode 100644
index ab32a05b19..0000000000
--- a/debian/patches-rt/0081-printk-nbcon-Add-emit-function-and-callback-function.patch
+++ /dev/null
@@ -1,262 +0,0 @@
-From: Thomas Gleixner <tglx@linutronix.de>
-Date: Sat, 16 Sep 2023 21:26:06 +0206
-Subject: [PATCH 081/134] printk: nbcon: Add emit function and callback
- function for atomic printing
-Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz
-
-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(-)
-
---- 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
- */
-@@ -252,12 +253,29 @@ 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
- * @write: Write callback to output messages (Optional)
-@@ -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;
---- 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
---- a/kernel/printk/nbcon.c
-+++ b/kernel/printk/nbcon.c
-@@ -221,7 +221,6 @@ void nbcon_seq_force(struct console *con
- * 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(st
- *
- * 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;
-@@ -785,6 +783,110 @@ static bool __nbcon_context_update_unsaf
- }
-
- /**
-+ * 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
- *
---- a/kernel/printk/printk.c
-+++ b/kernel/printk/printk.c
-@@ -698,9 +698,6 @@ static ssize_t msg_print_ext_body(char *
- 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(stru
- * 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;
-
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-05 02:11:26 +0000