lkml.org 
[lkml]   [2019]   [Jan]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v3 0/6] Static calls
From
On January 11, 2019 11:34:34 AM PST, Linus Torvalds <torvalds@linux-foundation.org> wrote:
>On Fri, Jan 11, 2019 at 11:24 AM <hpa@zytor.com> wrote:
>>
>> I still don't see why can't simply spin in the #BP handler until the
>patch is complete.
>
>So here's at least one problem:
>
>text_poke_bp()
> text_poke(addr, &int3, sizeof(int3));
> *interrupt*
> interrupt has a static call
> *BP*
> poke_int3_handler
> *BOOM*
>
>Note how at BOOM we cannot just spin (or return) to wait for the
>'int3' to be switched back. Becuase it never will. Because we are
>interrupting the thing that would do that switch-back.
>
>So we'd have to do the 'text_poke_bp()' sequence with interrupts
>disabled. Which we can't do right now at least, because part of that
>sequence involves that on_each_cpu(do_sync_core) thing, which needs
>interrupts enabled.
>
>See?
>
>Or am I missing something?
>
> Linus

Let me think about it.
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

\
 
 \ /
  Last update: 2019-01-13 01:36    [W:0.152 / U:1.108 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site