WARNING: at drivers/dma/dmaengine.c:352 dma_issue_pending_all+0x77/0x15d()

WARNING: at drivers/dma/dmaengine.c:352 dma_issue_pending_all+0x77/0x15d()

[Ingo Molnar]

FYI, i'm getting this on a testbox, on v2.6.29-rc2:

[   78.930438] ------------[ cut here ]------------
[   78.932162] ADDRCONF(NETDEV_UP): eth2: link is not ready
[   78.940748] WARNING: at drivers/dma/dmaengine.c:352 dma_issue_pending_all+0x77/0x15d()
[   78.948876] Hardware name: P4DC6
[   78.952232] client called dma_issue_pending_all without a referencePid: 0, comm: swapper Not tainted 2.6.29-rc2-tip #1
[   78.963176] Call Trace:
[   78.965747]  [<c0177cc9>] warn_slowpath+0x90/0xa6
[   78.970578]  [<c01a7266>] ? __lock_acquire+0x6f2/0x748
[   78.975835]  [<c01a56a9>] ? mark_held_locks+0x45/0x5c
[   78.981012]  [<c0d35100>] ? napi_complete+0x7a/0x97
[   78.986016]  [<c01a587b>] ? trace_hardirqs_on_caller+0x112/0x167
[   78.992139]  [<c01a58db>] ? trace_hardirqs_on+0xb/0xd
[   78.997311]  [<c075e8d4>] ? e1000_clean+0x5a6/0x5f2
[   79.002306]  [<c0d06b34>] dma_issue_pending_all+0x77/0x15d
[   79.007912]  [<c0d358ea>] net_rx_action+0x2cc/0x2e6
[   79.012911]  [<c017f69a>] __do_softirq+0xbb/0x1cf
[   79.017738]  [<c017f5df>] ? __do_softirq+0x0/0x1cf
[   79.022644]  <IRQ>  [<c01cadc5>] ? handle_fasteoi_irq+0x0/0x124
[   79.028778]  [<c017f585>] ? irq_exit+0x50/0xaa
[   79.033340]  [<c012aade>] ? do_IRQ+0x119/0x12f
[   79.037901]  [<c0127d8c>] ? common_interrupt+0x2c/0x34
[   79.043163]  [<c01a00d8>] ? tick_broadcast_oneshot_control+0x10c/0x42e
[   79.049807]  [<c0152398>] ? native_safe_halt+0xa/0xc
[   79.054896]  [<c012f7c1>] ? default_idle+0xbf/0xd2
[   79.059806]  [<c0125765>] ? cpu_idle+0x16a/0x1a4
[   79.064564]  [<c0f4f41f>] ? rest_init+0x53/0x55
[   79.069210] ---[ end trace 230444e9b1c5e1e1 ]---
[   79.074319] e1000: eth2 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX
[   79.083245] ADDRCONF(NETDEV_CHANGE): eth2: link becomes ready

the driver that just ran was e1000.

Btw., this format string:

        WARN_ONCE(dmaengine_ref_count == 0,
                  "client called %s without a reference", __func__);

is missing a \n.

	Ingo

Re: WARNING: at drivers/dma/dmaengine.c:352 dma_issue_pending_all+0x77/0x15d()

[Dan Williams]

On Mon, 2009-01-19 at 14:31 -0700, Ingo Molnar wrote:
> FYI, i'm getting this on a testbox, on v2.6.29-rc2:

Thanks for the report.  I assume this is with CONFIG_DMA_ENGINE=n?
dma_issue_pending_all should be a nop in that case.  I'll apply the
following with your confirmation.

Regards,
Dan

---
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 6df144a..9c53e5e 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -330,7 +330,7 @@ struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
 	int cpu;
 
 	WARN_ONCE(dmaengine_ref_count == 0,
-		  "client called %s without a reference", __func__);
+		  "client called %s without a reference\n", __func__);
 
 	cpu = get_cpu();
 	chan = per_cpu_ptr(channel_table[tx_type], cpu)->chan;
@@ -349,7 +349,7 @@ void dma_issue_pending_all(void)
 	struct dma_chan *chan;
 
 	WARN_ONCE(dmaengine_ref_count == 0,
-		  "client called %s without a reference", __func__);
+		  "client called %s without a reference\n", __func__);
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(device, &dma_device_list, global_node) {
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 64dea2a..c4a560e 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -390,11 +390,16 @@ static inline enum dma_status dma_async_is_complete(dma_cookie_t cookie,
 enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie);
 #ifdef CONFIG_DMA_ENGINE
 enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
+void dma_issue_pending_all(void);
 #else
 static inline enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
 {
 	return DMA_SUCCESS;
 }
+static inline void dma_issue_pending_all(void)
+{
+	do { } while (0);
+}
 #endif
 
 /* --- DMA device --- */
@@ -403,7 +408,6 @@ int dma_async_device_register(struct dma_device *device);
 void dma_async_device_unregister(struct dma_device *device);
 void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
 struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type);
-void dma_issue_pending_all(void);
 #define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)
 struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, void *fn_param);
 void dma_release_channel(struct dma_chan *chan);

Re: WARNING: at drivers/dma/dmaengine.c:352 dma_issue_pending_all+0x77/0x15d()

[Dan Williams]

On Mon, 2009-01-19 at 15:04 -0700, Dan Williams wrote:
> On Mon, 2009-01-19 at 14:31 -0700, Ingo Molnar wrote:
> > FYI, i'm getting this on a testbox, on v2.6.29-rc2:
> 
> Thanks for the report.  I assume this is with CONFIG_DMA_ENGINE=n?
> dma_issue_pending_all should be a nop in that case.  I'll apply the
> following with your confirmation.
> 

Spoke too soon, the call to dma_issue_pending_all is protected by ifdef
CONFIG_NET_DMA.  Reading that counter without synchronizing with
dma_list_mutex is a problem.  I think I'll just remove the warnings for
now.

--
Dan