Bug 83822

Summary:	device-offset test randomly fails because XCreatePixmap bits are undefined
Product:	cairo	Reporter:	Massimo <sixtysix>
Component:	xlib backend	Assignee:	Chris Wilson <chris>
Status:	RESOLVED MOVED	QA Contact:	cairo-bugs mailing list <cairo-bugs>
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:
Attachments:	proposed patch

Description Massimo 2014-09-13 16:56:48 UTC

Created attachment 106221 [details]
proposed patch

while running

DISPLAY=:2 make test TARGETS=image,xlib

with Xvfb on display :2, to check a fix for bug #74779, occasionally
device-offset.xlib-render-0_0.rgb24 was reported PASS, even if the code
modified was not executed at all by that test.

The problem is that in that test (and few others) a temporary Pixmap is
created on the server and because render-0_0 does not have FillRectangles
an image surface is used to clear the Pixmap, but because the image surface
is already 'clear' it is left untouched and in _cairo_surface_unmap the 'clear'
image is not unmapped because untouched (image->base.serial == 0)

http://cgit.freedesktop.org/cairo/tree/src/cairo-surface.c#n688

this means X's Pixmap is left in its original undefined state and only
occasionally it is clear.

I suggest to increment the serial member of the image_surface when the
'is_clear' state of the image_surface does not correspond to a clear
content of the corresponding xlib_surface, as in the attached patch.

Comment 1 GitLab Migration User 2018-08-25 13:33:40 UTC

-- GitLab Migration Automatic Message --

This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.

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