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drm: move lease init after validation in drm_lease_create

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Patch bd36d3bab2 fixed a deadlock in the
failure path of drm_lease_create. This made the partially initialized
lease object visible for a short window of time.

To avoid having the lessee state appear transiently, I've rearranged
the code so that the lessor fields are not filled in until the
parameters are all validated and the function will succeed.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171221065424.1304-1-keithp@keithp.com
This commit is contained in:
Keith Packard 2017-12-20 22:54:24 -08:00 committed by Daniel Vetter
parent ce0769e0ea
commit d2a48e5254
1 changed files with 11 additions and 11 deletions
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22
drivers/gpu/drm/drm_lease.c
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@ -220,17 +220,6 @@ static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr
mutex_lock(&dev->mode_config.idr_mutex);
/* Insert the new lessee into the tree */
id = idr_alloc(&(drm_lease_owner(lessor)->lessee_idr), lessee, 1, 0, GFP_KERNEL);
if (id < 0) {
error = id;
goto out_lessee;
}
lessee->lessee_id = id;
lessee->lessor = drm_master_get(lessor);
list_add_tail(&lessee->lessee_list, &lessor->lessees);
idr_for_each_entry(leases, entry, object) {
error = 0;
if (!idr_find(&dev->mode_config.crtc_idr, object))
@ -246,6 +235,17 @@ static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr
}
}
/* Insert the new lessee into the tree */
id = idr_alloc(&(drm_lease_owner(lessor)->lessee_idr), lessee, 1, 0, GFP_KERNEL);
if (id < 0) {
error = id;
goto out_lessee;
}
lessee->lessee_id = id;
lessee->lessor = drm_master_get(lessor);
list_add_tail(&lessee->lessee_list, &lessor->lessees);
/* Move the leases over */
lessee->leases = *leases;
DRM_DEBUG_LEASE("new lessee %d %p, lessor %d %p\n", lessee->lessee_id, lessee, lessor->lessee_id, lessor);