lkml.org 
[lkml]   [2022]   [May]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [GIT PULL] printk for 5.19
    On Thu 2022-05-26 00:08:46, John Ogness wrote:
    > On 2022-05-25, Linus Torvalds <torvalds@linux-foundation.org> wrote:
    > > On Mon, May 23, 2022 at 6:21 AM Petr Mladek <pmladek@suse.com> wrote:
    > >> There are situations when the kthreads are either not available or
    > >> not reliable, for example, early boot, suspend, or panic. In these
    > >> situations, printk() uses the legacy mode and tries to handle
    > >> consoles immediately.
    > >
    > > Looking through the commits, I don't see how that "printk: wake up all
    > > waiters" makes any sense at all.
    > >
    > > It *ALREADY* woke up all waiters as far as I can see.
    > >
    > > Doing a wake_up_interruptible() will stop waking things up only when
    > > it hits a *exclusive* waiter, and as far as I can tell, there are no
    > > exclusive waiters there.
    >
    > You are correct. @log_wait never has exclusive waiters. I will post a
    > patch to revert the change in question.

    John, Yes, please do so.

    > > But when I see something really core like printk() get confused and
    > > mis-understand basic wait queue behavior, that makes me go "This is
    > > WRONG".

    Linus, thanks a lot for catching and explaining the problem.

    Yeah, it is a shame. I have met code with exclusive waiters only once,
    8 years ago and completely forgot about it. I was curious how it
    worked with more log waiters but I put it into TODO list. The new
    code looked safe and I was too focused on finding potential problems.

    Best Regards,
    Petr

    \
     
     \ /
      Last update: 2022-05-26 14:10    [W:7.091 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site