From 95c081c17f284de50eaca60d4d55643a64d39019 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Tue, 21 Jun 2016 10:54:12 +0200 Subject: drm: Move master pointer from drm_minor to drm_device There can only be one current master, and it's for the overall device. Render/control minors don't support master-based auth at all. This simplifies the master logic a lot, at least in my eyes: All these additional pointer chases are just confusing. While doing the conversion I spotted some locking fail: - drm_lock/drm_auth check dev->master without holding the master_mutex. This is fallout from commit c996fd0b956450563454e7ccc97a82ca31f9d043 Author: Thomas Hellstrom Date: Tue Feb 25 19:57:44 2014 +0100 drm: Protect the master management with a drm_device::master_mutex v3 but I honestly don't care one bit about those old legacy drivers using this. - debugfs name info should just grab master_mutex. - And the fbdev helper looked at it to figure out whether someone is using KMS. We just need a consistent value, so READ_ONCE. Aside: We should probably check if anyone has opened a control node too, but I guess current userspace doesn't really do that yet. v2: Balance locking, reported by Julia. v3: Rebase on top of Chris' oops fixes. Cc: Julia Lawall Cc: Chris Wilson Reviewed-by: Chris Wilson (v2) Reviewed-by: Emil Velikov (v2) Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1466499262-18717-1-git-send-email-daniel.vetter@ffwll.ch --- drivers/gpu/drm/drm_info.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'drivers/gpu/drm/drm_info.c') diff --git a/drivers/gpu/drm/drm_info.c b/drivers/gpu/drm/drm_info.c index e2d2543d5bd0..d6cfd5340d52 100644 --- a/drivers/gpu/drm/drm_info.c +++ b/drivers/gpu/drm/drm_info.c @@ -50,7 +50,12 @@ int drm_name_info(struct seq_file *m, void *data) struct drm_info_node *node = (struct drm_info_node *) m->private; struct drm_minor *minor = node->minor; struct drm_device *dev = minor->dev; - struct drm_master *master = minor->master; + struct drm_master *master; + + mutex_lock(&dev->master_mutex); + master = dev->master; + if (!master) + goto out_unlock; seq_printf(m, "%s", dev->driver->name); if (dev->dev) @@ -60,6 +65,8 @@ int drm_name_info(struct seq_file *m, void *data) if (dev->unique) seq_printf(m, " unique=%s", dev->unique); seq_printf(m, "\n"); +out_unlock: + mutex_unlock(&dev->master_mutex); return 0; } -- cgit v1.2.3-59-g8ed1b