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gpu: nvgpu: stop timer on failing channel

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In gk20a_channel_timeout_handler(), below deadlock scenario
is possible :

thread 1:
- take global lock g->ch_wdt_lock
- identify timed out channel (as ch1)
- check engine status which is stuck
- identify failing channel on engine as ch2
- we need to trigger recovery with ch2
- as part of recovery, call channel_abort() for ch2
- in channel_abort(), we wait to cancel the timer wq
- but timer wq for ch2 never completes due to thread 2

thread 2:
- ch2 has already timed out
- to process, we wait for global lock g->ch_wdt_lock
- this lock needs to be released by thread 1

To fix this, cancel the timer (through flag) of ch2
(failing channel on engine) before triggering recovery
on that channel

Bug 200164753

Change-Id: Idb42d01c8440a53f43cb5e87e41f1c283f7e8fcf
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/929924
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>
This commit is contained in:
Deepak Nibade
2016-01-07 14:31:12 +05:30
committed by Terje Bergstrom
parent 9713e3572a
commit 0ce201e8de
1 changed files with 6 additions and 1 deletions
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7
drivers/gpu/nvgpu/gk20a/channel_gk20a.c
View File

@@ -1700,9 +1700,14 @@ static void gk20a_channel_timeout_handler(struct work_struct *work)
if (!failing_ch)
goto fail_enable_ctxsw;
if (failing_ch->hw_chid != ch->hw_chid)
if (failing_ch->hw_chid != ch->hw_chid) {
gk20a_channel_timeout_start(ch, job);
mutex_lock(&failing_ch->timeout.lock);
failing_ch->timeout.initialized = false;
mutex_unlock(&failing_ch->timeout.lock);
}
gk20a_fifo_recover(g, BIT(engine_id),
failing_ch->hw_chid, is_tsg,
true, failing_ch->timeout_debug_dump);