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The chances are decreased by starting > the teardown by releasing guc_id, but remain non-zero. > On the other hand the sync between fixups and context creation > drastically increases chance for such parallel teardown if > context creation fails. > I don't see how this is possible. xe_exec_queue_contexts_hwsp_rebase only happens if the exec queue is present in &guc->submission_state.exec_queue_lookup. 332 static void __xe_exec_queue_fini(struct xe_exec_queue *q) 333 { 334 int i; 335 336 q->ops->fini(q); 337 338 for (i = 0; i < q->width; ++i) 339 xe_lrc_put(q->lrc[i]); 340 } The removal from &guc->submission_state.exec_queue_lookup happen on line 336 in the above before. Thus a xe_exec_queue_contexts_hwsp_rebase can't be executing on a 'q' after line 336 returns, then we drop the references to the LRC. I agree this lifetime is questionable at best (IIRC my GuC documentation explain this why this works) but if there is a problem it should be fix with this lifetime in mind. Looking at __xe_exec_queue_init, I believe 'err_lrc' label should actually call __xe_exec_queue_fini. > Prevent LRC teardown in parallel with fixups by getting a reference. > > Signed-off-by: Tomasz Lis > --- > drivers/gpu/drm/xe/xe_exec_queue.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c > index 42849be46166..e9396ad3390a 100644 > --- a/drivers/gpu/drm/xe/xe_exec_queue.c > +++ b/drivers/gpu/drm/xe/xe_exec_queue.c > @@ -1669,10 +1669,11 @@ int xe_exec_queue_contexts_hwsp_rebase(struct xe_exec_queue *q, void *scratch) > lrc = READ_ONCE(q->lrc[i]); > if (!lrc) > continue; > - > + xe_lrc_get(lrc); This doesn't actually fix anything. The LRC could (current, in error paths) disappear between the read and get. Matt > xe_lrc_update_memirq_regs_with_address(lrc, q->hwe, scratch); > xe_lrc_update_hwctx_regs_with_address(lrc); > err = xe_lrc_setup_wa_bb_with_scratch(lrc, q->hwe, scratch); > + xe_lrc_put(lrc); > if (err) > break; > } > -- > 2.25.1 >