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Diffstat (limited to '')
-rw-r--r-- | debian/patches-rt/0003-printk-Avoid-non-panic-CPUs-writing-to-ringbuffer.patch | 86 |
1 files changed, 0 insertions, 86 deletions
diff --git a/debian/patches-rt/0003-printk-Avoid-non-panic-CPUs-writing-to-ringbuffer.patch b/debian/patches-rt/0003-printk-Avoid-non-panic-CPUs-writing-to-ringbuffer.patch deleted file mode 100644 index d7575e9a50..0000000000 --- a/debian/patches-rt/0003-printk-Avoid-non-panic-CPUs-writing-to-ringbuffer.patch +++ /dev/null @@ -1,86 +0,0 @@ -From: John Ogness <john.ogness@linutronix.de> -Date: Wed, 7 Feb 2024 14:47:01 +0106 -Subject: [PATCH 03/48] printk: Avoid non-panic CPUs writing to ringbuffer -Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz - -Commit 13fb0f74d702 ("printk: Avoid livelock with heavy printk -during panic") introduced a mechanism to silence non-panic CPUs -if too many messages are being dropped. Aside from trying to -workaround the livelock bugs of legacy consoles, it was also -intended to avoid losing panic messages. However, if non-panic -CPUs are writing to the ringbuffer, then reacting to dropped -messages is too late. - -Another motivation is that non-finalized messages already might -be skipped in panic(). In other words, random messages from -non-panic CPUs might already get lost. It is better to ignore -all to avoid confusion. - -To avoid losing panic CPU messages, silence non-panic CPUs -immediately on panic. - -Signed-off-by: John Ogness <john.ogness@linutronix.de> -Reviewed-by: Petr Mladek <pmladek@suse.com> -Link: https://lore.kernel.org/r/20240207134103.1357162-13-john.ogness@linutronix.de -Signed-off-by: Petr Mladek <pmladek@suse.com> -Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> ---- - kernel/printk/printk.c | 26 ++++++-------------------- - 1 file changed, 6 insertions(+), 20 deletions(-) - ---- a/kernel/printk/printk.c -+++ b/kernel/printk/printk.c -@@ -462,12 +462,6 @@ static int console_msg_format = MSG_FORM - static DEFINE_MUTEX(syslog_lock); - - #ifdef CONFIG_PRINTK --/* -- * During panic, heavy printk by other CPUs can delay the -- * panic and risk deadlock on console resources. -- */ --static int __read_mostly suppress_panic_printk; -- - DECLARE_WAIT_QUEUE_HEAD(log_wait); - /* All 3 protected by @syslog_lock. */ - /* the next printk record to read by syslog(READ) or /proc/kmsg */ -@@ -2322,7 +2316,12 @@ asmlinkage int vprintk_emit(int facility - if (unlikely(suppress_printk)) - return 0; - -- if (unlikely(suppress_panic_printk) && other_cpu_in_panic()) -+ /* -+ * The messages on the panic CPU are the most important. If -+ * non-panic CPUs are generating any messages, they will be -+ * silently dropped. -+ */ -+ if (other_cpu_in_panic()) - return 0; - - if (level == LOGLEVEL_SCHED) { -@@ -2807,8 +2806,6 @@ void console_prepend_dropped(struct prin - bool printk_get_next_message(struct printk_message *pmsg, u64 seq, - bool is_extended, bool may_suppress) - { -- static int panic_console_dropped; -- - struct printk_buffers *pbufs = pmsg->pbufs; - const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf); - const size_t outbuf_sz = sizeof(pbufs->outbuf); -@@ -2836,17 +2833,6 @@ bool printk_get_next_message(struct prin - pmsg->seq = r.info->seq; - pmsg->dropped = r.info->seq - seq; - -- /* -- * Check for dropped messages in panic here so that printk -- * suppression can occur as early as possible if necessary. -- */ -- if (pmsg->dropped && -- panic_in_progress() && -- panic_console_dropped++ > 10) { -- suppress_panic_printk = 1; -- pr_warn_once("Too many dropped messages. Suppress messages on non-panic CPUs to prevent livelock.\n"); -- } -- - /* Skip record that has level above the console loglevel. */ - if (may_suppress && suppress_message_printing(r.info->level)) - goto out; |