Messages in this thread | | | Date | Fri, 19 Feb 2021 13:59:09 +0100 | From | Petr Mladek <> | Subject | Re: [PATCH printk-rework 07/14] printk: use atomic64_t for devkmsg_user.seq |
| |
On Thu 2021-02-18 09:18:10, John Ogness wrote: > @user->seq is indirectly protected by @logbuf_lock. Once @logbuf_lock > is removed, @user->seq will be no longer safe from an atomicity point > of view. > > In preparation for the removal of @logbuf_lock, change it to > atomic64_t to provide this safety. > > Signed-off-by: John Ogness <john.ogness@linutronix.de> > --- > kernel/printk/printk.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) > > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index a71e0d41ccb5..20c21a25143d 100644 > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -865,9 +865,9 @@ static __poll_t devkmsg_poll(struct file *file, poll_table *wait) > poll_wait(file, &log_wait, wait); > > logbuf_lock_irq(); > - if (prb_read_valid_info(prb, user->seq, &info, NULL)) { > + if (prb_read_valid(prb, atomic64_read(&user->seq), NULL)) {
s/prb_read_valid/prb_read_valid_info/
It is likely a mistake when rebasing on top of the commit 13791c80b0cdf54d ("printk: avoid prb_first_valid_seq() where possible").
> /* return error when data has vanished underneath us */ > - if (info.seq != user->seq) > + if (info.seq != atomic64_read(&user->seq)) > ret = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; > else > ret = EPOLLIN|EPOLLRDNORM;
With the above fix:
Reviewed-by: Petr Mladek <pmladek@suse.com>
Best Regards, Petr
| |