On 10/16/2017 11:28 AM, Luck, Tony wrote:
> On Sun, Oct 15, 2017 at 11:40:46AM +0200, Borislav Petkov wrote:
>> On Wed, Oct 11, 2017 at 09:34:22PM +0000, Luck, Tony wrote:
>>>> here's a second attempt at a more rigorous simplification: RCU stuff is
>>>> gone and only a single loop scans through the elements.
>>>
>>> The dev_mce_log() changes look good now.
>>>
>>> You can apply the axe to more bits of mce_chrdev_read() though. Like that
>>
>> That provoked a very serious axing. Please check whether I went too far. Hunk
>> below is ontop of what got axed already:
>
> I think a few more lines can go. Almost everything relating to the "finished"
> element. dev_mce_log() must still set it (because the user mode mcelog(8)
> daemon will grumble if we give it records that don't have it set). But
> since everything is protected by mce_chrdev_read_mutex we can't have
> "Old left over entries" to skip. Nor is there any way that finished can't
> be set for an entry in 0..mcelog.next when it comes to mce_chrdev_read().
>
> This patch on top of your two???
>
Did these get queued up somewhere? I know last week was OSSEU/Ksummit
so people may still be playing catch-up.
Thanks,
Laura
> -Tony
>
> diff --git a/arch/x86/kernel/cpu/mcheck/dev-mcelog.c
> b/arch/x86/kernel/cpu/mcheck/dev-mcelog.c
> index 17d2bab25720..7f85b76f43bc 100644
> --- a/arch/x86/kernel/cpu/mcheck/dev-mcelog.c
> +++ b/arch/x86/kernel/cpu/mcheck/dev-mcelog.c
> @@ -49,11 +49,7 @@ static int dev_mce_log(struct notifier_block *nb, unsigned
> long val,
>
> mutex_lock(&mce_chrdev_read_mutex);
>
> - for (entry = mcelog.next; entry < MCE_LOG_LEN; entry++) {
> - /* Old left over entry. Skip: */
> - if (mcelog.entry[entry].finished)
> - continue;
> - }
> + entry = mcelog.next;
>
> /*
> * When the buffer fills up discard new entries. Assume that the
> @@ -231,9 +227,6 @@ static ssize_t mce_chrdev_read(struct file *filp, char
> __user *ubuf,
> for (i = 0; i < next; i++) {
> struct mce *m = &mcelog.entry[i];
>
> - if (!m->finished)
> - continue;
> -
> err |= copy_to_user(buf, m, sizeof(*m));
> buf += sizeof(*m);
> }
>
