@@ -190,18 +190,12 @@ static ssize_t dpms_show(struct device *device,
char *buf)
{
struct drm_connector *connector = to_drm_connector(device);
- struct drm_device *dev = connector->dev;
- uint64_t dpms_status;
- int ret;
+ int dpms;
- ret = drm_object_property_get_value(&connector->base,
- dev->mode_config.dpms_property,
- &dpms_status);
- if (ret)
- return 0;
+ dpms = READ_ONCE(connector->dpms);
return snprintf(buf, PAGE_SIZE, "%s\n",
- drm_get_dpms_name((int)dpms_status));
+ drm_get_dpms_name(dpms));
}
static ssize_t enabled_show(struct device *device,
This is a note to let you know that I have just added a patch titled drm: Fix locking for sysfs dpms file to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt10. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 0027f09ddc1b8e769b0cc300f7b9ceca80b6cbeb Mon Sep 17 00:00:00 2001 From: Daniel Vetter <daniel.vetter@ffwll.ch> Date: Tue, 29 Sep 2015 09:56:53 +0200 Subject: [PATCH 038/120] drm: Fix locking for sysfs dpms file commit 621bd0f6982badd6483acb191eb7b6226a578328 upstream. With atomic drivers we need to make sure that (at least in general) property reads hold the right locks. But the legacy dpms property is special and can be read locklessly. Since userspace loves to just randomly look at that all the time (like with "status") do that. To make it clear that we play tricks use the READ_ONCE compiler barrier (and also for paranoia). Note that there's not really anything bad going on since even with the new atomic paths we eventually end up not chasing any pointers (and hence possibly freed memory and other fun stuff). The locking WARNING has been added in commit 88a48e297b3a3bac6022c03babfb038f1a886cea Author: Rob Clark <robdclark@gmail.com> Date: Thu Dec 18 16:01:50 2014 -0500 drm: add atomic properties but since drivers are converting not everyone will have seen this from the start. Jens reported this and submitted a patch to just grab the mode_config.connection_mutex, but we can do a bit better. v2: Remove unused variables I failed to git add for real. Reference: http://mid.gmane.org/20150928194822.GA3930@kernel.dk Reported-by: Jens Axboe <axboe@fb.com> Tested-by: Jens Axboe <axboe@fb.com> Cc: Rob Clark <robdclark@gmail.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Signed-off-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/gpu/drm/drm_sysfs.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) -- 1.9.1