drm/xe/bo: don't hold dma-resv lock over drm_gem_handle_create

This seems to create a locking inversion with object_name_lock. The lock
is held by drm_prime_fd_to_handle when calling our xe_gem_prime_import
hook, which might eventually go on to grab the dma-resv lock during the
attach. However we also have the opposite locking order in
xe_gem_create_ioctl which is holding the dma-resv lock when calling
drm_gem_handle_create, which wants to eventually grab object_name_lock:

-> #1 (reservation_ww_class_mutex){+.+.}-{3:3}:
<4> [635.739288]        lock_acquire+0x169/0x3d0
<4> [635.739294]        __ww_mutex_lock.constprop.0+0x164/0x1e60
<4> [635.739300]        ww_mutex_lock_interruptible+0x42/0x1a0
<4> [635.739305]        drm_gem_shmem_pin+0x4b/0x140 [drm_shmem_helper]
<4> [635.739317]        dma_buf_dynamic_attach+0x101/0x430
<4> [635.739323]        xe_gem_prime_import+0xcc/0x2e0 [xe]
<4> [635.739499]        drm_prime_fd_to_handle_ioctl+0x184/0x2e0 [drm]
<4> [635.739594]        drm_ioctl_kernel+0x16f/0x250 [drm]
<4> [635.739693]        drm_ioctl+0x35e/0x620 [drm]
<4> [635.739789]        __x64_sys_ioctl+0xb7/0xf0
<4> [635.739794]        do_syscall_64+0x3c/0x90
<4> [635.739799]        entry_SYSCALL_64_after_hwframe+0x6e/0xd8
<4> [635.739805]
-> #0 (&dev->object_name_lock){+.+.}-{3:3}:
<4> [635.739813]        check_prev_add+0x1ba/0x14a0
<4> [635.739818]        __lock_acquire+0x203e/0x2ff0
<4> [635.739823]        lock_acquire+0x169/0x3d0
<4> [635.739827]        __mutex_lock+0x124/0x1310
<4> [635.739832]        drm_gem_handle_create+0x32/0x50 [drm]
<4> [635.739927]        xe_gem_create_ioctl+0x1d3/0x550 [xe]
<4> [635.740102]        drm_ioctl_kernel+0x16f/0x250 [drm]
<4> [635.740197]        drm_ioctl+0x35e/0x620 [drm]
<4> [635.740293]        __x64_sys_ioctl+0xb7/0xf0
<4> [635.740297]        do_syscall_64+0x3c/0x90
<4> [635.740302]        entry_SYSCALL_64_after_hwframe+0x6e/0xd8
<4> [635.740307]

It looks like it should be safe to simply drop the dma-resv lock prior
to publishing the object when calling drm_gem_handle_create.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/743
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

0 files changed, 0 insertions, 0 deletions