Re: [net PATCH] atl1e: fix dma mapping warnings

[Luis Henriques <luis.henriques@canonical.com>]

Neil Horman <nhorman@tuxdriver.com> writes:

> On Fri, Jul 12, 2013 at 05:04:26PM +0100, Luis Henriques wrote:
>> Neil Horman <nhorman@tuxdriver.com> writes:
>> 
>> > Recently had this backtrace reported:
>> > WARNING: at lib/dma-debug.c:937 check_unmap+0x47d/0x930()
>> > Hardware name: System Product Name
>> > ATL1E 0000:02:00.0: DMA-API: device driver failed to check map error[device
>> > address=0x00000000cbfd1000] [size=90 bytes] [mapped as single]
>> > Modules linked in: xt_conntrack nf_conntrack ebtable_filter ebtables
>> > ip6table_filter ip6_tables snd_hda_codec_hdmi snd_hda_codec_realtek iTCO_wdt
>> > iTCO_vendor_support snd_hda_intel acpi_cpufreq mperf coretemp btrfs zlib_deflate
>> > snd_hda_codec snd_hwdep microcode raid6_pq libcrc32c snd_seq usblp serio_raw xor
>> > snd_seq_device joydev snd_pcm snd_page_alloc snd_timer snd lpc_ich i2c_i801
>> > soundcore mfd_core atl1e asus_atk0110 ata_generic pata_acpi radeon i2c_algo_bit
>> > drm_kms_helper ttm drm i2c_core pata_marvell uinput
>> > Pid: 314, comm: systemd-journal Not tainted 3.9.0-0.rc6.git2.3.fc19.x86_64 #1
>> > Call Trace:
>> >  <IRQ>  [<ffffffff81069106>] warn_slowpath_common+0x66/0x80
>> >  [<ffffffff8106916c>] warn_slowpath_fmt+0x4c/0x50
>> >  [<ffffffff8138151d>] check_unmap+0x47d/0x930
>> >  [<ffffffff810ad048>] ? sched_clock_cpu+0xa8/0x100
>> >  [<ffffffff81381a2f>] debug_dma_unmap_page+0x5f/0x70
>> >  [<ffffffff8137ce30>] ? unmap_single+0x20/0x30
>> >  [<ffffffffa01569a1>] atl1e_intr+0x3a1/0x5b0 [atl1e]
>> >  [<ffffffff810d53fd>] ? trace_hardirqs_off+0xd/0x10
>> >  [<ffffffff81119636>] handle_irq_event_percpu+0x56/0x390
>> >  [<ffffffff811199ad>] handle_irq_event+0x3d/0x60
>> >  [<ffffffff8111cb6a>] handle_fasteoi_irq+0x5a/0x100
>> >  [<ffffffff8101c36f>] handle_irq+0xbf/0x150
>> >  [<ffffffff811dcb2f>] ? file_sb_list_del+0x3f/0x50
>> >  [<ffffffff81073b10>] ? irq_enter+0x50/0xa0
>> >  [<ffffffff8172738d>] do_IRQ+0x4d/0xc0
>> >  [<ffffffff811dcb2f>] ? file_sb_list_del+0x3f/0x50
>> >  [<ffffffff8171c6b2>] common_interrupt+0x72/0x72
>> >  <EOI>  [<ffffffff810db5b2>] ? lock_release+0xc2/0x310
>> >  [<ffffffff8109ea04>] lg_local_unlock_cpu+0x24/0x50
>> >  [<ffffffff811dcb2f>] file_sb_list_del+0x3f/0x50
>> >  [<ffffffff811dcb6d>] fput+0x2d/0xc0
>> >  [<ffffffff811d8ea1>] filp_close+0x61/0x90
>> >  [<ffffffff811fae4d>] __close_fd+0x8d/0x150
>> >  [<ffffffff811d8ef0>] sys_close+0x20/0x50
>> >  [<ffffffff81725699>] system_call_fastpath+0x16/0x1b
>> >
>> > The usual straighforward failure to check for dma_mapping_error after a map
>> > operation is completed.
>> >
>> > This patch should fix it, the reporter wandered off after filing this bz:
>> > https://bugzilla.redhat.com/show_bug.cgi?id=954170
>> >
>> > and I don't have hardware to test, but the fix is pretty straightforward, so I
>> > figured I'd post it for review.
>> >
>> > Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
>> > CC: Jay Cliburn <jcliburn@gmail.com>
>> > CC: Chris Snook <chris.snook@gmail.com>
>> > CC: "David S. Miller" <davem@davemloft.net>
>> > ---
>> >  drivers/net/ethernet/atheros/atl1e/atl1e_main.c | 26 +++++++++++++++++++++++--
>> >  1 file changed, 24 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/net/ethernet/atheros/atl1e/atl1e_main.c b/drivers/net/ethernet/atheros/atl1e/atl1e_main.c
>> > index 895f537..53a725b 100644
>> > --- a/drivers/net/ethernet/atheros/atl1e/atl1e_main.c
>> > +++ b/drivers/net/ethernet/atheros/atl1e/atl1e_main.c
>> > @@ -1665,7 +1665,7 @@ check_sum:
>> >  	return 0;
>> >  }
>> >  
>> > -static void atl1e_tx_map(struct atl1e_adapter *adapter,
>> > +static int atl1e_tx_map(struct atl1e_adapter *adapter,
>> >  		      struct sk_buff *skb, struct atl1e_tpd_desc *tpd)
>> >  {
>> >  	struct atl1e_tpd_desc *use_tpd = NULL;
>> > @@ -1677,6 +1677,7 @@ static void atl1e_tx_map(struct atl1e_adapter *adapter,
>> >  	u16 nr_frags;
>> >  	u16 f;
>> >  	int segment;
>> > +	int ring_start = adapter->tx_ring.next_to_use;
>> >  
>> >  	nr_frags = skb_shinfo(skb)->nr_frags;
>> >  	segment = (tpd->word3 >> TPD_SEGMENT_EN_SHIFT) & TPD_SEGMENT_EN_MASK;
>> > @@ -1689,6 +1690,9 @@ static void atl1e_tx_map(struct atl1e_adapter *adapter,
>> >  		tx_buffer->length = map_len;
>> >  		tx_buffer->dma = pci_map_single(adapter->pdev,
>> >  					skb->data, hdr_len, PCI_DMA_TODEVICE);
>> > +		if (dma_mapping_error(&adapter->pdev->dev, tx_buffer->dma))
>> > +			return -ENOSPC;
>> > +
>> >  		ATL1E_SET_PCIMAP_TYPE(tx_buffer, ATL1E_TX_PCIMAP_SINGLE);
>> >  		mapped_len += map_len;
>> >  		use_tpd->buffer_addr = cpu_to_le64(tx_buffer->dma);
>> > @@ -1715,6 +1719,13 @@ static void atl1e_tx_map(struct atl1e_adapter *adapter,
>> >  		tx_buffer->dma =
>> >  			pci_map_single(adapter->pdev, skb->data + mapped_len,
>> >  					map_len, PCI_DMA_TODEVICE);
>> > +
>> > +		if (dma_mapping_error(&adapter->pdev->dev, tx_buffer->dma)) {
>> > +			/* Reset the tx rings next pointer */
>> > +			adapter->tx_ring.next_to_use = ring_start;
>> > +			return -ENOSPC;
>> > +		}
>> > +
>> >  		ATL1E_SET_PCIMAP_TYPE(tx_buffer, ATL1E_TX_PCIMAP_SINGLE);
>> >  		mapped_len  += map_len;
>> >  		use_tpd->buffer_addr = cpu_to_le64(tx_buffer->dma);
>> > @@ -1750,6 +1761,13 @@ static void atl1e_tx_map(struct atl1e_adapter *adapter,
>> >  							  (i * MAX_TX_BUF_LEN),
>> >  							  tx_buffer->length,
>> >  							  DMA_TO_DEVICE);
>> > +
>> > +			if (dma_mapping_error(&adapter->pdev->dev, tx_buffer->dma)) {
>> > +				/* Reset the ring next to use pointer */
>> > +				adapter->tx_ring.next_to_use = ring_start;
>> > +				return -ENOSPC;
>> > +			}
>> > +
>> >  			ATL1E_SET_PCIMAP_TYPE(tx_buffer, ATL1E_TX_PCIMAP_PAGE);
>> >  			use_tpd->buffer_addr = cpu_to_le64(tx_buffer->dma);
>> >  			use_tpd->word2 = (use_tpd->word2 & (~TPD_BUFLEN_MASK)) |
>> > @@ -1767,6 +1785,7 @@ static void atl1e_tx_map(struct atl1e_adapter *adapter,
>> >  	/* The last buffer info contain the skb address,
>> >  	   so it will be free after unmap */
>> >  	tx_buffer->skb = skb;
>> > +	return 0;
>> 
>> Looks good to me, except from return statement in a void function.
>> 
>> Cheers,
>> -- 
>> Luis
>> 
> Actually scratch that last note, I don't see any return statements in fuctions
> that return void.  I modified atl1e_tx_map to return an int so we could do the
> right thing in atl1e_xmit_frame.  Is there something I'm missing?
> Neil

Ups, you're right.  Sorry for the noise.

So, just as a suggestion, maybe your patch should also change
atl1e_xmit_frame to do something with the new return code (maybe
return NETDEV_TX_BUSY...)

Cheers,
-- 
Luis