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net: ll_temac: Fix RX buffer descriptor handling on GFP_ATOMIC pressure

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Failures caused by GFP_ATOMIC memory pressure have been observed, and
due to the missing error handling, results in kernel crash such as

[1876998.350133] kernel BUG at mm/slub.c:3952!
[1876998.350141] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[1876998.350147] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.3.0-scnxt #1
[1876998.350150] Hardware name: N/A N/A/COMe-bIP2, BIOS CCR2R920 03/01/2017
[1876998.350160] RIP: 0010:kfree+0x1ca/0x220
[1876998.350164] Code: 85 db 74 49 48 8b 95 68 01 00 00 48 31 c2 48 89 10 e9 d7 fe ff ff 49 8b 04 24 a9 00 00 01 00 75 0b 49 8b 44 24 08 a8 01 75 02 <0f> 0b 49 8b 04 24 31 f6 a9 00 00 01 00 74 06 41 0f b6 74 24
 5b
[1876998.350172] RSP: 0018:ffffc900000f0df0 EFLAGS: 00010246
[1876998.350177] RAX: ffffea00027f0708 RBX: ffff888008d78000 RCX: 0000000000391372
[1876998.350181] RDX: 0000000000000000 RSI: ffffe8ffffd01400 RDI: ffff888008d78000
[1876998.350185] RBP: ffff8881185a5d00 R08: ffffc90000087dd8 R09: 000000000000280a
[1876998.350189] R10: 0000000000000002 R11: 0000000000000000 R12: ffffea0000235e00
[1876998.350193] R13: ffff8881185438a0 R14: 0000000000000000 R15: ffff888118543870
[1876998.350198] FS:  0000000000000000(0000) GS:ffff88811f300000(0000) knlGS:0000000000000000
[1876998.350203] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
s#1 Part1
[1876998.350206] CR2: 00007f8dac7b09f0 CR3: 000000011e20a006 CR4: 00000000001606e0
[1876998.350210] Call Trace:
[1876998.350215]  <IRQ>
[1876998.350224]  ? __netif_receive_skb_core+0x70a/0x920
[1876998.350229]  kfree_skb+0x32/0xb0
[1876998.350234]  __netif_receive_skb_core+0x70a/0x920
[1876998.350240]  __netif_receive_skb_one_core+0x36/0x80
[1876998.350245]  process_backlog+0x8b/0x150
[1876998.350250]  net_rx_action+0xf7/0x340
[1876998.350255]  __do_softirq+0x10f/0x353
[1876998.350262]  irq_exit+0xb2/0xc0
[1876998.350265]  do_IRQ+0x77/0xd0
[1876998.350271]  common_interrupt+0xf/0xf
[1876998.350274]  </IRQ>

In order to handle such failures more graceful, this change splits the
receive loop into one for consuming the received buffers, and one for
allocating new buffers.

When GFP_ATOMIC allocations fail, the receive will continue with the
buffers that is still there, and with the expectation that the allocations
will succeed in a later call to receive.

Fixes: 9274498953 ("net: add Xilinx ll_temac device driver")
Signed-off-by: Esben Haabendal <esben@geanix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Esben Haabendal 2020-02-21 07:47:45 +01:00 committed by David S. Miller
parent d07c849cd2
commit 770d9c6797
2 changed files with 81 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/net/ethernet/xilinx/ll_temac.h
View File

@ -375,6 +375,7 @@ struct temac_local {
int tx_bd_next;
int tx_bd_tail;
int rx_bd_ci;
int rx_bd_tail;
/* DMA channel control setup */
u32 tx_chnl_ctrl;

110
drivers/net/ethernet/xilinx/ll_temac_main.c
View File

@ -389,12 +389,13 @@ static int temac_dma_bd_init(struct net_device *ndev)
lp->tx_bd_next = 0;
lp->tx_bd_tail = 0;
lp->rx_bd_ci = 0;
lp->rx_bd_tail = RX_BD_NUM - 1;
/* Enable RX DMA transfers */
wmb();
lp->dma_out(lp, RX_CURDESC_PTR, lp->rx_bd_p);
lp->dma_out(lp, RX_TAILDESC_PTR,
lp->rx_bd_p + (sizeof(*lp->rx_bd_v) * (RX_BD_NUM - 1)));
lp->rx_bd_p + (sizeof(*lp->rx_bd_v) * lp->rx_bd_tail));
/* Prepare for TX DMA transfer */
lp->dma_out(lp, TX_CURDESC_PTR, lp->tx_bd_p);
@ -923,27 +924,41 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
static void ll_temac_recv(struct net_device *ndev)
{
struct temac_local *lp = netdev_priv(ndev);
struct sk_buff *skb, *new_skb;
unsigned int bdstat;
struct cdmac_bd *cur_p;
dma_addr_t tail_p, skb_dma_addr;
int length;
unsigned long flags;
int rx_bd;
bool update_tail = false;
spin_lock_irqsave(&lp->rx_lock, flags);
tail_p = lp->rx_bd_p + sizeof(*lp->rx_bd_v) * lp->rx_bd_ci;
cur_p = &lp->rx_bd_v[lp->rx_bd_ci];
/* Process all received buffers, passing them on network
* stack. After this, the buffer descriptors will be in an
* un-allocated stage, where no skb is allocated for it, and
* they are therefore not available for TEMAC/DMA.
*/
do {
struct cdmac_bd *bd = &lp->rx_bd_v[lp->rx_bd_ci];
struct sk_buff *skb = lp->rx_skb[lp->rx_bd_ci];
unsigned int bdstat = be32_to_cpu(bd->app0);
int length;
bdstat = be32_to_cpu(cur_p->app0);
while ((bdstat & STS_CTRL_APP0_CMPLT)) {
/* While this should not normally happen, we can end
* here when GFP_ATOMIC allocations fail, and we
* therefore have un-allocated buffers.
*/
if (!skb)
break;
skb = lp->rx_skb[lp->rx_bd_ci];
length = be32_to_cpu(cur_p->app4) & 0x3FFF;
/* Loop over all completed buffer descriptors */
if (!(bdstat & STS_CTRL_APP0_CMPLT))
break;
dma_unmap_single(ndev->dev.parent, be32_to_cpu(cur_p->phys),
dma_unmap_single(ndev->dev.parent, be32_to_cpu(bd->phys),
XTE_MAX_JUMBO_FRAME_SIZE, DMA_FROM_DEVICE);
/* The buffer is not valid for DMA anymore */
bd->phys = 0;
bd->len = 0;
length = be32_to_cpu(bd->app4) & 0x3FFF;
skb_put(skb, length);
skb->protocol = eth_type_trans(skb, ndev);
skb_checksum_none_assert(skb);
@ -958,39 +973,74 @@ static void ll_temac_recv(struct net_device *ndev)
* (back) for proper IP checksum byte order
* (be16).
*/
skb->csum = htons(be32_to_cpu(cur_p->app3) & 0xFFFF);
skb->csum = htons(be32_to_cpu(bd->app3) & 0xFFFF);
skb->ip_summed = CHECKSUM_COMPLETE;
}
if (!skb_defer_rx_timestamp(skb))
netif_rx(skb);
/* The skb buffer is now owned by network stack above */
lp->rx_skb[lp->rx_bd_ci] = NULL;
ndev->stats.rx_packets++;
ndev->stats.rx_bytes += length;
new_skb = netdev_alloc_skb_ip_align(ndev,
XTE_MAX_JUMBO_FRAME_SIZE);
if (!new_skb) {
spin_unlock_irqrestore(&lp->rx_lock, flags);
return;
rx_bd = lp->rx_bd_ci;
if (++lp->rx_bd_ci >= RX_BD_NUM)
lp->rx_bd_ci = 0;
} while (rx_bd != lp->rx_bd_tail);
/* Allocate new buffers for those buffer descriptors that were
* passed to network stack. Note that GFP_ATOMIC allocations
* can fail (e.g. when a larger burst of GFP_ATOMIC
* allocations occurs), so while we try to allocate all
* buffers in the same interrupt where they were processed, we
* continue with what we could get in case of allocation
* failure. Allocation of remaining buffers will be retried
* in following calls.
*/
while (1) {
struct sk_buff *skb;
struct cdmac_bd *bd;
dma_addr_t skb_dma_addr;
rx_bd = lp->rx_bd_tail + 1;
if (rx_bd >= RX_BD_NUM)
rx_bd = 0;
bd = &lp->rx_bd_v[rx_bd];
if (bd->phys)
break; /* All skb's allocated */
skb = netdev_alloc_skb_ip_align(ndev, XTE_MAX_JUMBO_FRAME_SIZE);
if (!skb) {
dev_warn(&ndev->dev, "skb alloc failed\n");
break;
}
cur_p->app0 = cpu_to_be32(STS_CTRL_APP0_IRQONEND);
skb_dma_addr = dma_map_single(ndev->dev.parent, new_skb->data,
skb_dma_addr = dma_map_single(ndev->dev.parent, skb->data,
XTE_MAX_JUMBO_FRAME_SIZE,
DMA_FROM_DEVICE);
cur_p->phys = cpu_to_be32(skb_dma_addr);
cur_p->len = cpu_to_be32(XTE_MAX_JUMBO_FRAME_SIZE);
lp->rx_skb[lp->rx_bd_ci] = new_skb;
if (WARN_ON_ONCE(dma_mapping_error(ndev->dev.parent,
skb_dma_addr))) {
dev_kfree_skb_any(skb);
break;
}
lp->rx_bd_ci++;
if (lp->rx_bd_ci >= RX_BD_NUM)
lp->rx_bd_ci = 0;
bd->phys = cpu_to_be32(skb_dma_addr);
bd->len = cpu_to_be32(XTE_MAX_JUMBO_FRAME_SIZE);
bd->app0 = cpu_to_be32(STS_CTRL_APP0_IRQONEND);
lp->rx_skb[rx_bd] = skb;
cur_p = &lp->rx_bd_v[lp->rx_bd_ci];
bdstat = be32_to_cpu(cur_p->app0);
lp->rx_bd_tail = rx_bd;
update_tail = true;
}
/* Move tail pointer when buffers have been allocated */
if (update_tail) {
lp->dma_out(lp, RX_TAILDESC_PTR,
lp->rx_bd_p + sizeof(*lp->rx_bd_v) * lp->rx_bd_tail);
}
lp->dma_out(lp, RX_TAILDESC_PTR, tail_p);
spin_unlock_irqrestore(&lp->rx_lock, flags);
}