vt: Fix timer race between vtterm_splash() and vt_flush()
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Authored by quentin.thebault_defenso.fr on Wed, Sep 23, 2:43 PM.

Details

Reviewers

vexeduxr
emaste

Summary

Current code leads to console text being drawn over the splash image.

Ensure vt_flush() does not draw over the splash image: vtterm_splash()
holds the vd_flush_lock via VT_FLUSH_LOCK(), or the vtbuf lock,
depending on the framebuffer backend, while it sets VDF_SPLASH and
blits. vt_flush() takes the same lock and re-checks VDF_SPLASH.

Sponsored by: Defenso
Signed-off-by: Quentin Thébault <quentin.thebault@defenso.fr>

Diff Detail

Repository

rG FreeBSD src repository

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Lint Skipped

Unit

Tests Skipped

Build Status

Buildable 77209
Build 74092: arc lint + arc unit

Event Timeline

quentin.thebault_defenso.fr created this revision.Wed, Sep 23, 2:43 PM

Herald added a subscriber: imp. · View Herald TranscriptWed, Sep 23, 2:43 PM

quentin.thebault_defenso.fr requested review of this revision.Wed, Sep 23, 2:43 PM

Harbormaster completed remote builds in B77209: Diff 187504.Wed, Sep 23, 2:44 PM

vexeduxr added inline comments.Wed, Sep 23, 9:46 PM

sys/dev/vt/vt_core.c
1743	Can we unlock right after setting `VDF_SPLASH`?

quentin.thebault_defenso.fr added inline comments.Fri, Sep 25, 2:42 PM

sys/dev/vt/vt_core.c
1743	Yes you are right that is enough. Once `VDF_SPLASH` is set the flush won´t stomp over our blit.

Release lock before blit rather than after.

Harbormaster completed remote builds in B77328: Diff 187677.Fri, Sep 25, 2:47 PM

quentin.thebault_defenso.fr marked an inline comment as done.Fri, Sep 25, 2:47 PM

Revision Contents
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Path

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sys/

dev/

vt/

vt_core.c

37 lines

Diff 187504

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vt: Fix timer race between vtterm_splash() and vt_flush()Needs ReviewPublicActions