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authorJesse Brandeburg <jesse.brandeburg@intel.com>2015-02-24 00:26:03 -0500
committerJeff Kirsher <jeffrey.t.kirsher@intel.com>2015-02-26 07:53:59 -0500
commita68de58d2791dd9f2b159703b70377011b35a568 (patch)
treebabbcc9ce7bfcb265702fc03ce6a42b0d01f80eb /drivers/net
parent71da61976ec18fb57b3ba9a1dd846b747cc7c884 (diff)
i40e: fix race in hang check
The driver was having some issues with false Tx hang detection. This makes the driver a little more direct with the checks for progress forward by directly checking the head write back address and tail register when determining progress. This avoids Tx hangs where the software gets behind, because we are directly checking hardware state when determining hang state. Change-ID: I774f0e861c9e8ab5ccb213634100fe15440ae24a Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com> Tested-by: Jim Young <james.m.young@intel.com> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/ethernet/intel/i40e/i40e_txrx.c54
-rw-r--r--drivers/net/ethernet/intel/i40evf/i40e_txrx.c54
2 files changed, 60 insertions, 48 deletions
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 0aad61170f75..bbf1b1247ac4 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -586,6 +586,20 @@ void i40e_free_tx_resources(struct i40e_ring *tx_ring)
586} 586}
587 587
588/** 588/**
589 * i40e_get_head - Retrieve head from head writeback
590 * @tx_ring: tx ring to fetch head of
591 *
592 * Returns value of Tx ring head based on value stored
593 * in head write-back location
594 **/
595static inline u32 i40e_get_head(struct i40e_ring *tx_ring)
596{
597 void *head = (struct i40e_tx_desc *)tx_ring->desc + tx_ring->count;
598
599 return le32_to_cpu(*(volatile __le32 *)head);
600}
601
602/**
589 * i40e_get_tx_pending - how many tx descriptors not processed 603 * i40e_get_tx_pending - how many tx descriptors not processed
590 * @tx_ring: the ring of descriptors 604 * @tx_ring: the ring of descriptors
591 * 605 *
@@ -594,10 +608,16 @@ void i40e_free_tx_resources(struct i40e_ring *tx_ring)
594 **/ 608 **/
595static u32 i40e_get_tx_pending(struct i40e_ring *ring) 609static u32 i40e_get_tx_pending(struct i40e_ring *ring)
596{ 610{
597 u32 ntu = ((ring->next_to_clean <= ring->next_to_use) 611 u32 head, tail;
598 ? ring->next_to_use 612
599 : ring->next_to_use + ring->count); 613 head = i40e_get_head(ring);
600 return ntu - ring->next_to_clean; 614 tail = readl(ring->tail);
615
616 if (head != tail)
617 return (head < tail) ?
618 tail - head : (tail + ring->count - head);
619
620 return 0;
601} 621}
602 622
603/** 623/**
@@ -606,6 +626,8 @@ static u32 i40e_get_tx_pending(struct i40e_ring *ring)
606 **/ 626 **/
607static bool i40e_check_tx_hang(struct i40e_ring *tx_ring) 627static bool i40e_check_tx_hang(struct i40e_ring *tx_ring)
608{ 628{
629 u32 tx_done = tx_ring->stats.packets;
630 u32 tx_done_old = tx_ring->tx_stats.tx_done_old;
609 u32 tx_pending = i40e_get_tx_pending(tx_ring); 631 u32 tx_pending = i40e_get_tx_pending(tx_ring);
610 struct i40e_pf *pf = tx_ring->vsi->back; 632 struct i40e_pf *pf = tx_ring->vsi->back;
611 bool ret = false; 633 bool ret = false;
@@ -623,41 +645,25 @@ static bool i40e_check_tx_hang(struct i40e_ring *tx_ring)
623 * run the check_tx_hang logic with a transmit completion 645 * run the check_tx_hang logic with a transmit completion
624 * pending but without time to complete it yet. 646 * pending but without time to complete it yet.
625 */ 647 */
626 if ((tx_ring->tx_stats.tx_done_old == tx_ring->stats.packets) && 648 if ((tx_done_old == tx_done) && tx_pending) {
627 (tx_pending >= I40E_MIN_DESC_PENDING)) {
628 /* make sure it is true for two checks in a row */ 649 /* make sure it is true for two checks in a row */
629 ret = test_and_set_bit(__I40E_HANG_CHECK_ARMED, 650 ret = test_and_set_bit(__I40E_HANG_CHECK_ARMED,
630 &tx_ring->state); 651 &tx_ring->state);
631 } else if ((tx_ring->tx_stats.tx_done_old == tx_ring->stats.packets) && 652 } else if (tx_done_old == tx_done &&
632 (tx_pending < I40E_MIN_DESC_PENDING) && 653 (tx_pending < I40E_MIN_DESC_PENDING) && (tx_pending > 0)) {
633 (tx_pending > 0)) {
634 if (I40E_DEBUG_FLOW & pf->hw.debug_mask) 654 if (I40E_DEBUG_FLOW & pf->hw.debug_mask)
635 dev_info(tx_ring->dev, "HW needs some more descs to do a cacheline flush. tx_pending %d, queue %d", 655 dev_info(tx_ring->dev, "HW needs some more descs to do a cacheline flush. tx_pending %d, queue %d",
636 tx_pending, tx_ring->queue_index); 656 tx_pending, tx_ring->queue_index);
637 pf->tx_sluggish_count++; 657 pf->tx_sluggish_count++;
638 } else { 658 } else {
639 /* update completed stats and disarm the hang check */ 659 /* update completed stats and disarm the hang check */
640 tx_ring->tx_stats.tx_done_old = tx_ring->stats.packets; 660 tx_ring->tx_stats.tx_done_old = tx_done;
641 clear_bit(__I40E_HANG_CHECK_ARMED, &tx_ring->state); 661 clear_bit(__I40E_HANG_CHECK_ARMED, &tx_ring->state);
642 } 662 }
643 663
644 return ret; 664 return ret;
645} 665}
646 666
647/**
648 * i40e_get_head - Retrieve head from head writeback
649 * @tx_ring: tx ring to fetch head of
650 *
651 * Returns value of Tx ring head based on value stored
652 * in head write-back location
653 **/
654static inline u32 i40e_get_head(struct i40e_ring *tx_ring)
655{
656 void *head = (struct i40e_tx_desc *)tx_ring->desc + tx_ring->count;
657
658 return le32_to_cpu(*(volatile __le32 *)head);
659}
660
661#define WB_STRIDE 0x3 667#define WB_STRIDE 0x3
662 668
663/** 669/**
diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
index 1320a433b8ed..be05829ba619 100644
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
@@ -126,6 +126,20 @@ void i40evf_free_tx_resources(struct i40e_ring *tx_ring)
126} 126}
127 127
128/** 128/**
129 * i40e_get_head - Retrieve head from head writeback
130 * @tx_ring: tx ring to fetch head of
131 *
132 * Returns value of Tx ring head based on value stored
133 * in head write-back location
134 **/
135static inline u32 i40e_get_head(struct i40e_ring *tx_ring)
136{
137 void *head = (struct i40e_tx_desc *)tx_ring->desc + tx_ring->count;
138
139 return le32_to_cpu(*(volatile __le32 *)head);
140}
141
142/**
129 * i40e_get_tx_pending - how many tx descriptors not processed 143 * i40e_get_tx_pending - how many tx descriptors not processed
130 * @tx_ring: the ring of descriptors 144 * @tx_ring: the ring of descriptors
131 * 145 *
@@ -134,10 +148,16 @@ void i40evf_free_tx_resources(struct i40e_ring *tx_ring)
134 **/ 148 **/
135static u32 i40e_get_tx_pending(struct i40e_ring *ring) 149static u32 i40e_get_tx_pending(struct i40e_ring *ring)
136{ 150{
137 u32 ntu = ((ring->next_to_clean <= ring->next_to_use) 151 u32 head, tail;
138 ? ring->next_to_use 152
139 : ring->next_to_use + ring->count); 153 head = i40e_get_head(ring);
140 return ntu - ring->next_to_clean; 154 tail = readl(ring->tail);
155
156 if (head != tail)
157 return (head < tail) ?
158 tail - head : (tail + ring->count - head);
159
160 return 0;
141} 161}
142 162
143/** 163/**
@@ -146,6 +166,8 @@ static u32 i40e_get_tx_pending(struct i40e_ring *ring)
146 **/ 166 **/
147static bool i40e_check_tx_hang(struct i40e_ring *tx_ring) 167static bool i40e_check_tx_hang(struct i40e_ring *tx_ring)
148{ 168{
169 u32 tx_done = tx_ring->stats.packets;
170 u32 tx_done_old = tx_ring->tx_stats.tx_done_old;
149 u32 tx_pending = i40e_get_tx_pending(tx_ring); 171 u32 tx_pending = i40e_get_tx_pending(tx_ring);
150 bool ret = false; 172 bool ret = false;
151 173
@@ -162,36 +184,20 @@ static bool i40e_check_tx_hang(struct i40e_ring *tx_ring)
162 * run the check_tx_hang logic with a transmit completion 184 * run the check_tx_hang logic with a transmit completion
163 * pending but without time to complete it yet. 185 * pending but without time to complete it yet.
164 */ 186 */
165 if ((tx_ring->tx_stats.tx_done_old == tx_ring->stats.packets) && 187 if ((tx_done_old == tx_done) && tx_pending) {
166 (tx_pending >= I40E_MIN_DESC_PENDING)) {
167 /* make sure it is true for two checks in a row */ 188 /* make sure it is true for two checks in a row */
168 ret = test_and_set_bit(__I40E_HANG_CHECK_ARMED, 189 ret = test_and_set_bit(__I40E_HANG_CHECK_ARMED,
169 &tx_ring->state); 190 &tx_ring->state);
170 } else if (!(tx_ring->tx_stats.tx_done_old == tx_ring->stats.packets) || 191 } else if (tx_done_old == tx_done &&
171 !(tx_pending < I40E_MIN_DESC_PENDING) || 192 (tx_pending < I40E_MIN_DESC_PENDING) && (tx_pending > 0)) {
172 !(tx_pending > 0)) {
173 /* update completed stats and disarm the hang check */ 193 /* update completed stats and disarm the hang check */
174 tx_ring->tx_stats.tx_done_old = tx_ring->stats.packets; 194 tx_ring->tx_stats.tx_done_old = tx_done;
175 clear_bit(__I40E_HANG_CHECK_ARMED, &tx_ring->state); 195 clear_bit(__I40E_HANG_CHECK_ARMED, &tx_ring->state);
176 } 196 }
177 197
178 return ret; 198 return ret;
179} 199}
180 200
181/**
182 * i40e_get_head - Retrieve head from head writeback
183 * @tx_ring: tx ring to fetch head of
184 *
185 * Returns value of Tx ring head based on value stored
186 * in head write-back location
187 **/
188static inline u32 i40e_get_head(struct i40e_ring *tx_ring)
189{
190 void *head = (struct i40e_tx_desc *)tx_ring->desc + tx_ring->count;
191
192 return le32_to_cpu(*(volatile __le32 *)head);
193}
194
195#define WB_STRIDE 0x3 201#define WB_STRIDE 0x3
196 202
197/** 203/**