• Rob Clark's avatar
    drm/msm: fix locking inconsistencies in gpu->destroy() · 774449eb
    Rob Clark authored
    In error paths, this was being called without struct_mutex held.
    Leading to panics like:
    
      msm 1a00000.qcom,mdss_mdp: No memory protection without IOMMU
      Kernel panic - not syncing: BUG!
      CPU: 0 PID: 1409 Comm: cat Not tainted 4.0.0-dirty #4
      Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
      Call trace:
      [<ffffffc000089c78>] dump_backtrace+0x0/0x118
      [<ffffffc000089da0>] show_stack+0x10/0x20
      [<ffffffc0006686d4>] dump_stack+0x84/0xc4
      [<ffffffc0006678b4>] panic+0xd0/0x210
      [<ffffffc0003e1ce4>] drm_gem_object_free+0x5c/0x60
      [<ffffffc000402870>] adreno_gpu_cleanup+0x60/0x80
      [<ffffffc0004035a0>] a3xx_destroy+0x20/0x70
      [<ffffffc0004036f4>] a3xx_gpu_init+0x84/0x108
      [<ffffffc0004018b8>] adreno_load_gpu+0x58/0x190
      [<ffffffc000419dac>] msm_open+0x74/0x88
      [<ffffffc0003e0a48>] drm_open+0x168/0x400
      [<ffffffc0003e7210>] drm_stub_open+0xa8/0x118
      [<ffffffc0001a0e84>] chrdev_open+0x94/0x198
      [<ffffffc000199f88>] do_dentry_open+0x208/0x310
      [<ffffffc00019a4c4>] vfs_open+0x44/0x50
      [<ffffffc0001aa26c>] do_last.isra.14+0x2c4/0xc10
      [<ffffffc0001aac38>] path_openat+0x80/0x5e8
      [<ffffffc0001ac354>] do_filp_open+0x2c/0x98
      [<ffffffc00019b60c>] do_sys_open+0x13c/0x228
      [<ffffffc00019b72c>] SyS_openat+0xc/0x18
      CPU1: stopping
    
    But there isn't any particularly good reason to hold struct_mutex for
    teardown, so just standardize on calling it without the mutex held and
    use the _unlocked() versions for GEM obj unref'ing
    Signed-off-by: default avatarRob Clark <robdclark@gmail.com>
    774449eb
msm_ringbuffer.c 1.47 KB