| From | John Ogness <> | Subject | [PATCH printk v3 17/40] printk: console_unblank: use srcu console list iterator | Date | Mon, 7 Nov 2022 15:22:15 +0106 |
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Use srcu console list iteration for console list traversal.
Document why the console_lock is still necessary. Note that this is a preparatory change for when console_lock no longer provides synchronization for the console list.
Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> --- kernel/printk/printk.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 49b9ba00eae8..c3191dc24742 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2952,10 +2952,14 @@ EXPORT_SYMBOL(console_conditional_schedule); void console_unblank(void) { struct console *c; + int cookie; /* - * console_unblank can no longer be called in interrupt context unless - * oops_in_progress is set to 1.. + * Stop console printing because the unblank() callback may + * assume the console is not within its write() callback. + * + * If @oops_in_progress is set, this may be an atomic context. + * In that case, attempt a trylock as best-effort. */ if (oops_in_progress) { if (down_trylock_console_sem() != 0) @@ -2965,9 +2969,14 @@ void console_unblank(void) console_locked = 1; console_may_schedule = 0; - for_each_console(c) + + cookie = console_srcu_read_lock(); + for_each_console_srcu(c) { if (console_is_enabled(c) && c->unblank) c->unblank(); + } + console_srcu_read_unlock(cookie); + console_unlock(); if (!oops_in_progress) -- 2.30.2
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