blk-mq: Remove 'running from the wrong CPU' warning

It's guaranteed that no request is in flight when a hctx is going offline. This warning is only triggered when the wq's CPU is hot plugged and the blk-mq is not synced up yet. As this state is temporary and the request is still processed correctly, better remove the warning as this is the fast path. Suggested-by: Ming Lei <[email protected]> Signed-off-by: Daniel Wagner <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Reviewed-by: Ming Lei <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
lbl96 · Dec 16, 2020 · e6582cb · e6582cb
1 parent 009bd55
commit e6582cb
Showing 1 changed file with 0 additions and 25 deletions.
diff --git a/block/blk-mq.c b/block/blk-mq.c
@@ -1495,31 +1495,6 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
 {
 	int srcu_idx;
 
-	/*
-	 * We should be running this queue from one of the CPUs that
-	 * are mapped to it.
-	 *
-	 * There are at least two related races now between setting
-	 * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
-	 * __blk_mq_run_hw_queue():
-	 *
-	 * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
-	 *   but later it becomes online, then this warning is harmless
-	 *   at all
-	 *
-	 * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
-	 *   but later it becomes offline, then the warning can't be
-	 *   triggered, and we depend on blk-mq timeout handler to
-	 *   handle dispatched requests to this hctx
-	 */
-	if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
-		cpu_online(hctx->next_cpu)) {
-		printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
-			raw_smp_processor_id(),
-			cpumask_empty(hctx->cpumask) ? "inactive": "active");
-		dump_stack();
-	}
-
 	/*
 	 * We can't run the queue inline with ints disabled. Ensure that
 	 * we catch bad users of this early.