[cairo-bugs] [Bug 98883] BadAccess errors in ShmAttach due to thread races with XNextRequest() usage in cairo-xlib-surface-shm.c

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Thu Jul 26 01:53:30 UTC 2018


--- Comment #11 from Daniel van Vugt <daniel.van.vugt at canonical.com> ---
It's been a few months so my memory is not completely clear. I do however think
Uli's statement is incorrect in the final two sentences:

> What the patch does is to make XShmAttach synchronous (aka "slow"). I do not
> know why, but nothing in this bug report suggests that this is necessary.
> The description of the patch does not say anything about this either.
> XShmAttach() should not just randomly fail, so why does the patch try to
> handle random failures?

attachment 139297 mentions multiple times "why" it is necessary to make it
synchronous. Because it's impossible to detect errors in XShmAttach otherwise.

It's possible we're using to the wrong bug here, but I believe the patch is
still correct and we have no choice but to make XShmAttach slow. You can only
choose between maximum performance or reliable error handling, and not have
both. The reasons are detailed in attachment 139297.

You are receiving this mail because:
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cairographics.org/archives/cairo-bugs/attachments/20180726/d973ad04/attachment-0001.html>

More information about the cairo-bugs mailing list