diff options
Diffstat (limited to 'features/rt/printk-change-console_seq-to-atomic64_t.patch')
| -rw-r--r-- | features/rt/printk-change-console_seq-to-atomic64_t.patch | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/features/rt/printk-change-console_seq-to-atomic64_t.patch b/features/rt/printk-change-console_seq-to-atomic64_t.patch new file mode 100644 index 00000000..36f793a1 --- /dev/null +++ b/features/rt/printk-change-console_seq-to-atomic64_t.patch @@ -0,0 +1,131 @@ +From b90a5d78be04a9b45524b66bd55a22e56f247633 Mon Sep 17 00:00:00 2001 +From: John Ogness <john.ogness@linutronix.de> +Date: Mon, 30 Nov 2020 01:42:05 +0106 +Subject: [PATCH 028/191] printk: change @console_seq to atomic64_t + +In preparation for atomic printing, change @console_seq to atomic +so that it can be accessed without requiring @console_sem. + +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + kernel/printk/printk.c | 34 +++++++++++++++++++--------------- + 1 file changed, 19 insertions(+), 15 deletions(-) + +diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c +index 2b13deb971b9..28bd7a7807bc 100644 +--- a/kernel/printk/printk.c ++++ b/kernel/printk/printk.c +@@ -366,12 +366,13 @@ static u64 syslog_seq; + static size_t syslog_partial; + static bool syslog_time; + +-/* All 3 protected by @console_sem. */ +-/* the next printk record to write to the console */ +-static u64 console_seq; ++/* Both protected by @console_sem. */ + static u64 exclusive_console_stop_seq; + static unsigned long console_dropped; + ++/* the next printk record to write to the console */ ++static atomic64_t console_seq = ATOMIC64_INIT(0); ++ + struct latched_seq { + seqcount_latch_t latch; + u64 val[2]; +@@ -2270,7 +2271,7 @@ EXPORT_SYMBOL(printk); + #define prb_first_valid_seq(rb) 0 + + static u64 syslog_seq; +-static u64 console_seq; ++static atomic64_t console_seq = ATOMIC64_INIT(0); + static u64 exclusive_console_stop_seq; + static unsigned long console_dropped; + +@@ -2585,6 +2586,7 @@ void console_unlock(void) + bool do_cond_resched, retry; + struct printk_info info; + struct printk_record r; ++ u64 seq; + + if (console_suspended) { + up_console_sem(); +@@ -2627,12 +2629,14 @@ void console_unlock(void) + size_t len; + + skip: +- if (!prb_read_valid(prb, console_seq, &r)) ++ seq = atomic64_read(&console_seq); ++ if (!prb_read_valid(prb, seq, &r)) + break; + +- if (console_seq != r.info->seq) { +- console_dropped += r.info->seq - console_seq; +- console_seq = r.info->seq; ++ if (seq != r.info->seq) { ++ console_dropped += r.info->seq - seq; ++ atomic64_set(&console_seq, r.info->seq); ++ seq = r.info->seq; + } + + if (suppress_message_printing(r.info->level)) { +@@ -2641,13 +2645,13 @@ void console_unlock(void) + * directly to the console when we received it, and + * record that has level above the console loglevel. + */ +- console_seq++; ++ atomic64_set(&console_seq, seq + 1); + goto skip; + } + + /* Output to all consoles once old messages replayed. */ + if (unlikely(exclusive_console && +- console_seq >= exclusive_console_stop_seq)) { ++ seq >= exclusive_console_stop_seq)) { + exclusive_console = NULL; + } + +@@ -2668,7 +2672,7 @@ void console_unlock(void) + len = record_print_text(&r, + console_msg_format & MSG_FORMAT_SYSLOG, + printk_time); +- console_seq++; ++ atomic64_set(&console_seq, seq + 1); + + /* + * While actively printing out messages, if another printk() +@@ -2699,7 +2703,7 @@ void console_unlock(void) + * there's a new owner and the console_unlock() from them will do the + * flush, no worries. + */ +- retry = prb_read_valid(prb, console_seq, NULL); ++ retry = prb_read_valid(prb, atomic64_read(&console_seq), NULL); + if (retry && console_trylock()) + goto again; + } +@@ -2762,7 +2766,7 @@ void console_flush_on_panic(enum con_flush_mode mode) + console_may_schedule = 0; + + if (mode == CONSOLE_REPLAY_ALL) +- console_seq = prb_first_valid_seq(prb); ++ atomic64_set(&console_seq, prb_first_valid_seq(prb)); + console_unlock(); + } + +@@ -2999,11 +3003,11 @@ void register_console(struct console *newcon) + * ignores console_lock. + */ + exclusive_console = newcon; +- exclusive_console_stop_seq = console_seq; ++ exclusive_console_stop_seq = atomic64_read(&console_seq); + + /* Get a consistent copy of @syslog_seq. */ + spin_lock_irqsave(&syslog_lock, flags); +- console_seq = syslog_seq; ++ atomic64_set(&console_seq, syslog_seq); + spin_unlock_irqrestore(&syslog_lock, flags); + } + console_unlock(); +-- +2.19.1 + |