lkml.org 
[lkml]   [2022]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH printk v5 10/40] proc: consoles: document console_lock usage
Date
The console_lock is held throughout the start/show/stop procedure
to print out device/driver information about all registered
consoles. Since the console_lock is being used for multiple reasons,
explicitly document these reasons. This will be useful when the
console_lock is split into fine-grained locking.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
---
fs/proc/consoles.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c
index cf2e0788f9c7..46b305fa04ed 100644
--- a/fs/proc/consoles.c
+++ b/fs/proc/consoles.c
@@ -63,6 +63,15 @@ static void *c_start(struct seq_file *m, loff_t *pos)
struct console *con;
loff_t off = 0;

+ /*
+ * Take console_lock to serialize device() callback with
+ * other console operations. For example, fg_console is
+ * modified under console_lock when switching vt.
+ *
+ * Hold the console_lock to guarantee safe traversal of the
+ * console list. SRCU cannot be used because there is no
+ * place to store the SRCU cookie.
+ */
console_lock();
for_each_console(con)
if (off++ == *pos)
--
2.30.2
\
 
 \ /
  Last update: 2022-11-16 17:22    [W:0.378 / U:0.312 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site