From: Hans de Goede <hdegoede@redhat.com>
Date: Tue, 16 Jul 2024 15:46:09 +0000 (+0200)
Subject: rules: Add uaccess tag to /dev/udmabuf
X-Git-Tag: v257-rc1~897
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fd820e76e4999b4eee13be87fee25f5ffe357a57;p=thirdparty%2Fsystemd.git

rules: Add uaccess tag to /dev/udmabuf

In some cases userspace may need to create dmabuffers from userspace
on such example is the software ISP part of libcamera which needs to
allocate dma-buffers for the output of the software ISP.

At first the plan was to allow console users access to /dev/dma_heap/*,
this was discussed with various kernel folks here:
https://lore.kernel.org/all/bb372250-e8b8-4458-bc99-dd8365b06991@redhat.com/

Giving console users access to the dma_heap's was deemed a bad idea
because memory allocated this way is not accounted in cgroup limits.

Giving access to /dev/udmabuf OTOH was deemed acceptable so that
is what this patch adds.

Resolves: #32662
---

diff --git a/rules.d/70-uaccess.rules.in b/rules.d/70-uaccess.rules.in
index b82ce04a39d..e683bb11144 100644
--- a/rules.d/70-uaccess.rules.in
+++ b/rules.d/70-uaccess.rules.in
@@ -34,6 +34,8 @@ SUBSYSTEM=="sound", TAG+="uaccess", \
 SUBSYSTEM=="video4linux", TAG+="uaccess"
 SUBSYSTEM=="dvb", TAG+="uaccess"
 SUBSYSTEM=="media", TAG+="uaccess"
+# libcamera software ISP used with some cams requires udmabuf access
+KERNEL=="udmabuf", TAG+="uaccess"
 
 # industrial cameras, some webcams, camcorders, set-top boxes, TV sets, audio devices, and more
 SUBSYSTEM=="firewire", TEST=="units", ENV{IEEE1394_UNIT_FUNCTION_MIDI}=="1", TAG+="uaccess"