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| author | John Ogness <john.ogness@linutronix.de> | 2022-11-16 17:27:24 +0106 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2022-12-02 11:25:00 +0100 |
| commit | 100bdef2c198b8dc64df011dc4a2152db913c8ba (patch) | |
| tree | 49aa89134c32a85a46b6fb7d38015a12bbb37b38 /kernel/printk | |
| parent | 4dc64682ad37abb02c54ca598430ac27de60c21a (diff) | |
| download | linux-stable-100bdef2c198b8dc64df011dc4a2152db913c8ba.tar.gz linux-stable-100bdef2c198b8dc64df011dc4a2152db913c8ba.tar.bz2 linux-stable-100bdef2c198b8dc64df011dc4a2152db913c8ba.zip | |
console: introduce wrappers to read/write console flags
After switching to SRCU for console list iteration, some readers
will begin readings console->flags as a data race. Locklessly
reading console->flags provides a consistent value because there
is at most one CPU modifying console->flags and that CPU is
using only read-modify-write operations.
Introduce a wrapper for SRCU iterators to read console flags.
Introduce a matching wrapper to write to flags of registered
consoles. Writing to flags of registered consoles is synchronized
by the console_list_lock.
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/20221116162152.193147-13-john.ogness@linutronix.de
Diffstat (limited to 'kernel/printk')
| -rw-r--r-- | kernel/printk/printk.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 2b4506673a86..cad65d34c96d 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3069,7 +3069,7 @@ void console_stop(struct console *console) __pr_flush(console, 1000, true); console_list_lock(); console_lock(); - console->flags &= ~CON_ENABLED; + console_srcu_write_flags(console, console->flags & ~CON_ENABLED); console_unlock(); console_list_unlock(); @@ -3087,7 +3087,7 @@ void console_start(struct console *console) { console_list_lock(); console_lock(); - console->flags |= CON_ENABLED; + console_srcu_write_flags(console, console->flags | CON_ENABLED); console_unlock(); console_list_unlock(); __pr_flush(console, 1000, true); @@ -3343,7 +3343,7 @@ void register_console(struct console *newcon) } else if (newcon->flags & CON_CONSDEV) { /* Only the new head can have CON_CONSDEV set. */ - console_first()->flags &= ~CON_CONSDEV; + console_srcu_write_flags(console_first(), console_first()->flags & ~CON_CONSDEV); hlist_add_head_rcu(&newcon->node, &console_list); } else { @@ -3400,7 +3400,7 @@ static int unregister_console_locked(struct console *console) console_lock(); /* Disable it unconditionally */ - console->flags &= ~CON_ENABLED; + console_srcu_write_flags(console, console->flags & ~CON_ENABLED); if (hlist_unhashed(&console->node)) { console_unlock(); @@ -3419,7 +3419,7 @@ static int unregister_console_locked(struct console *console) * console has any device attached. Oh well.... */ if (!hlist_empty(&console_list) && console->flags & CON_CONSDEV) - console_first()->flags |= CON_CONSDEV; + console_srcu_write_flags(console_first(), console_first()->flags | CON_CONSDEV); console_unlock(); |