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authorJohn Ogness <john.ogness@linutronix.de>2022-11-16 17:27:28 +0106
committerPetr Mladek <pmladek@suse.com>2022-12-02 11:25:00 +0100
commiteb7f1ed2509c6223d960a7d69644a8eb506b13d0 (patch)
treeecd6a939f5050316b7ecf741d188d283f3886138 /kernel/printk/printk.c
parentfc956ae0de7fa25f99114609f21b76e7d38dc25c (diff)
printk: __pr_flush: use srcu console list iterator
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> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20221116162152.193147-17-john.ogness@linutronix.de
Diffstat (limited to 'kernel/printk/printk.c')
-rw-r--r--kernel/printk/printk.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 13bc960c7aa5..abdbd3ffb068 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3561,6 +3561,7 @@ 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;
@@ -3571,9 +3572,15 @@ 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))
@@ -3582,6 +3589,7 @@ 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