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drm/mst: fix recursive sleep warning on qlock

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With drm-next, we can get a backtrace from sleeping
with mutex detection.

this is due to the callback checking the txmsg state taking
the mutex, which can cause a sleep inside a sleep,

Daniel went over it and was happy we could drop this mutex
in this case.

Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Daniel Vetter 2015-01-28 10:02:23 +01:00 committed by Dave Airlie
parent 9a6f513014
commit cd961bb9ee
1 changed files with 8 additions and 3 deletions
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11
drivers/gpu/drm/drm_dp_mst_topology.c
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@ -733,10 +733,14 @@ static bool check_txmsg_state(struct drm_dp_mst_topology_mgr *mgr,
struct drm_dp_sideband_msg_tx *txmsg)
{
bool ret;
mutex_lock(&mgr->qlock);
/*
* All updates to txmsg->state are protected by mgr->qlock, and the two
* cases we check here are terminal states. For those the barriers
* provided by the wake_up/wait_event pair are enough.
*/
ret = (txmsg->state == DRM_DP_SIDEBAND_TX_RX ||
txmsg->state == DRM_DP_SIDEBAND_TX_TIMEOUT);
mutex_unlock(&mgr->qlock);
return ret;
}
@ -1363,12 +1367,13 @@ static int process_single_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
return 0;
}
/* must be called holding qlock */
static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
{
struct drm_dp_sideband_msg_tx *txmsg;
int ret;
WARN_ON(!mutex_is_locked(&mgr->qlock));
/* construct a chunk from the first msg in the tx_msg queue */
if (list_empty(&mgr->tx_msg_downq)) {
mgr->tx_down_in_progress = false;