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Differential D13835

Make use of mallocarray(9) in drm drivers.
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Authored by pfg on Jan 10 2018, 8:40 PM.
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dumbbell
pfg
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rS328261: drm2: Basic use of mallocarray(9).
Summary

These seem like easy cases where we can use mallocarray(9), however I am
unsure if doing such changes will increase the difficulty for future
merges.

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pfg created this revision.Jan 10 2018, 8:40 PM
Harbormaster completed remote builds in B14262: Diff 37748.Jan 10 2018, 8:40 PM
Herald added a subscriber: imp. · View Herald TranscriptJan 10 2018, 8:40 PM
dumbbell added a comment.Jan 10 2018, 10:52 PM

Hi!

What is the benefit of using mallocarray() here?

pfg added a comment.Jan 10 2018, 11:52 PM
In D13835#290226, @dumbbell wrote:

Hi!

What is the benefit of using mallocarray() here?

TBH, I don't think there is any chance of an overflow with real hardware. Perhaps in a virtualized world there may be a chance to cause an overflow on anything or with specialized hardware (like the PS4 hackers did) but that's pretty extreme.
I am trying to keep the kernel consistent using mallocarray(9) where it can be used, but I am OK if you don't want this.

The code should be eaiser to read, but it will also make merging back the code to stable a nightmare.

pfg updated this revision to Diff 37871.Jan 12 2018, 4:44 PM

This should be a minimal and more straightforward replacement.

Note that we now panic if there is an overflow.

Harbormaster completed remote builds in B14335: Diff 37871.Jan 12 2018, 4:44 PM
pfg accepted this revision.Jan 22 2018, 2:35 AM

This is small enough that shouldn't affect upstream merging (also the code is very FreeBSD-specific).
It also respects the general objective of the code.

This revision is now accepted and ready to land.Jan 22 2018, 2:35 AM
dumbbell accepted this revision.Jan 22 2018, 7:39 AM

Yes, that's fine, the patch is small enough. Thank you!

Closed by commit rS328261: drm2: Basic use of mallocarray(9). (authored by pfg). · Explain WhyJan 22 2018, 3:56 PM
This revision was automatically updated to reflect the committed changes.

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head/
sys/
dev/
drm2/
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head/sys/dev/drm2/drm_mem_util.h

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