On Wed 2022-10-19 17:01:47, John Ogness wrote: > 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@xxxxxxxxxxxxx> > --- > fs/proc/consoles.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c > index cf2e0788f9c7..32512b477605 100644 > --- a/fs/proc/consoles.c > +++ b/fs/proc/consoles.c > @@ -63,6 +63,14 @@ static void *c_start(struct seq_file *m, loff_t *pos) > struct console *con; > loff_t off = 0; > > + /* > + * Stop console printing because the device() callback may > + * assume the console is not within its write() callback. Like in previous patches, I would prefer to add more information about this dependency. An example or if it is just to stay on the safe side. > + * > + * 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. It might be possible to crate a custom struct for passing both the next struct console and SRCU cookie. But it probably is not worth it. > + */ > console_lock(); > for_each_console(con) > if (off++ == *pos) Best Regards, Petr
