Messages in this thread Patch in this message | | | From | John Ogness <> | Subject | [PATCH printk v5 16/40] printk: __pr_flush: use srcu console list iterator | Date | Wed, 16 Nov 2022 17:27:28 +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 | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 3a7b1931b7c9..6666cc27a014 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3560,6 +3560,7 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre struct console *c; u64 last_diff = 0; u64 printk_seq; + int cookie; u64 diff; u64 seq; @@ -3570,9 +3571,15 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre for (;;) { diff = 0; + /* + * Hold the console_lock to guarantee safe access to + * console->seq and to prevent changes to @console_suspended + * until all consoles have been processed. + */ console_lock(); - for_each_console(c) { + cookie = console_srcu_read_lock(); + for_each_console_srcu(c) { if (con && con != c) continue; if (!console_is_usable(c)) @@ -3581,6 +3588,7 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre if (printk_seq < seq) diff += seq - printk_seq; } + console_srcu_read_unlock(cookie); /* * If consoles are suspended, it cannot be expected that they -- 2.30.2
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