[Intel-wired-lan] [PATCH AUTOSEL 4.19 504/671] i40e: reduce stack usage in i40e_set_fc

[Intel-wired-lan] [PATCH AUTOSEL 4.19 504/671] i40e: reduce stack usage in i40e_set_fc

[Sasha Levin]

From: Arnd Bergmann <arnd@arndb.de>

[ Upstream commit 33b165684ab70867d4545643f550a5d48d3ddc57 ]

The functions i40e_aq_get_phy_abilities_resp() and i40e_set_fc() both
have giant structure on the stack, which makes each one use stack frames
larger than 500 bytes.

As clang decides one function into the other, we get a warning for
exceeding the frame size limit on 32-bit architectures:

drivers/net/ethernet/intel/i40e/i40e_common.c:1654:23: error: stack frame size of 1116 bytes in function 'i40e_set_fc' [-Werror,-Wframe-larger-than=]

When building with gcc, the inlining does not happen, but i40e_set_fc()
calls i40e_aq_get_phy_abilities_resp() anyway, so they add up on the
kernel stack just as much.

The parts that actually use large stacks don't overlap, so make sure
each one is a separate function, and mark them as noinline_for_stack to
prevent the compilers from combining them again.

Fixes: 0a862b43acc6 ("i40e/i40evf: Add module_types and update_link_info")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/i40e/i40e_common.c | 91 +++++++++++--------
 1 file changed, 51 insertions(+), 40 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_common.c b/drivers/net/ethernet/intel/i40e/i40e_common.c
index 85f75b5978fc..eb0ae6ab01e2 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_common.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_common.c
@@ -1668,25 +1668,15 @@ enum i40e_status_code i40e_aq_set_phy_config(struct i40e_hw *hw,
 	return status;
 }
 
-/**
- * i40e_set_fc
- * @hw: pointer to the hw struct
- * @aq_failures: buffer to return AdminQ failure information
- * @atomic_restart: whether to enable atomic link restart
- *
- * Set the requested flow control mode using set_phy_config.
- **/
-enum i40e_status_code i40e_set_fc(struct i40e_hw *hw, u8 *aq_failures,
-				  bool atomic_restart)
+static noinline_for_stack enum i40e_status_code
+i40e_set_fc_status(struct i40e_hw *hw,
+		   struct i40e_aq_get_phy_abilities_resp *abilities,
+		   bool atomic_restart)
 {
-	enum i40e_fc_mode fc_mode = hw->fc.requested_mode;
-	struct i40e_aq_get_phy_abilities_resp abilities;
 	struct i40e_aq_set_phy_config config;
-	enum i40e_status_code status;
+	enum i40e_fc_mode fc_mode = hw->fc.requested_mode;
 	u8 pause_mask = 0x0;
 
-	*aq_failures = 0x0;
-
 	switch (fc_mode) {
 	case I40E_FC_FULL:
 		pause_mask |= I40E_AQ_PHY_FLAG_PAUSE_TX;
@@ -1702,6 +1692,48 @@ enum i40e_status_code i40e_set_fc(struct i40e_hw *hw, u8 *aq_failures,
 		break;
 	}
 
+	memset(&config, 0, sizeof(struct i40e_aq_set_phy_config));
+	/* clear the old pause settings */
+	config.abilities = abilities->abilities & ~(I40E_AQ_PHY_FLAG_PAUSE_TX) &
+			   ~(I40E_AQ_PHY_FLAG_PAUSE_RX);
+	/* set the new abilities */
+	config.abilities |= pause_mask;
+	/* If the abilities have changed, then set the new config */
+	if (config.abilities == abilities->abilities)
+		return 0;
+
+	/* Auto restart link so settings take effect */
+	if (atomic_restart)
+		config.abilities |= I40E_AQ_PHY_ENABLE_ATOMIC_LINK;
+	/* Copy over all the old settings */
+	config.phy_type = abilities->phy_type;
+	config.phy_type_ext = abilities->phy_type_ext;
+	config.link_speed = abilities->link_speed;
+	config.eee_capability = abilities->eee_capability;
+	config.eeer = abilities->eeer_val;
+	config.low_power_ctrl = abilities->d3_lpan;
+	config.fec_config = abilities->fec_cfg_curr_mod_ext_info &
+			    I40E_AQ_PHY_FEC_CONFIG_MASK;
+
+	return i40e_aq_set_phy_config(hw, &config, NULL);
+}
+
+/**
+ * i40e_set_fc
+ * @hw: pointer to the hw struct
+ * @aq_failures: buffer to return AdminQ failure information
+ * @atomic_restart: whether to enable atomic link restart
+ *
+ * Set the requested flow control mode using set_phy_config.
+ **/
+enum i40e_status_code i40e_set_fc(struct i40e_hw *hw, u8 *aq_failures,
+				  bool atomic_restart)
+{
+	struct i40e_aq_get_phy_abilities_resp abilities;
+	enum i40e_status_code status;
+
+	*aq_failures = 0x0;
+
 	/* Get the current phy config */
 	status = i40e_aq_get_phy_capabilities(hw, false, false, &abilities,
 					      NULL);
@@ -1710,31 +1742,10 @@ enum i40e_status_code i40e_set_fc(struct i40e_hw *hw, u8 *aq_failures,
 		return status;
 	}
 
-	memset(&config, 0, sizeof(struct i40e_aq_set_phy_config));
-	/* clear the old pause settings */
-	config.abilities = abilities.abilities & ~(I40E_AQ_PHY_FLAG_PAUSE_TX) &
-			   ~(I40E_AQ_PHY_FLAG_PAUSE_RX);
-	/* set the new abilities */
-	config.abilities |= pause_mask;
-	/* If the abilities have changed, then set the new config */
-	if (config.abilities != abilities.abilities) {
-		/* Auto restart link so settings take effect */
-		if (atomic_restart)
-			config.abilities |= I40E_AQ_PHY_ENABLE_ATOMIC_LINK;
-		/* Copy over all the old settings */
-		config.phy_type = abilities.phy_type;
-		config.phy_type_ext = abilities.phy_type_ext;
-		config.link_speed = abilities.link_speed;
-		config.eee_capability = abilities.eee_capability;
-		config.eeer = abilities.eeer_val;
-		config.low_power_ctrl = abilities.d3_lpan;
-		config.fec_config = abilities.fec_cfg_curr_mod_ext_info &
-				    I40E_AQ_PHY_FEC_CONFIG_MASK;
-		status = i40e_aq_set_phy_config(hw, &config, NULL);
+	status = i40e_set_fc_status(hw, &abilities, atomic_restart);
+	if (status)
+		*aq_failures |= I40E_SET_FC_AQ_FAIL_SET;
 
-		if (status)
-			*aq_failures |= I40E_SET_FC_AQ_FAIL_SET;
-	}
 	/* Update the link info */
 	status = i40e_update_link_info(hw);
 	if (status) {
@@ -2563,7 +2574,7 @@ i40e_status i40e_get_link_status(struct i40e_hw *hw, bool *link_up)
  * i40e_updatelink_status - update status of the HW network link
  * @hw: pointer to the hw struct
  **/
-i40e_status i40e_update_link_info(struct i40e_hw *hw)
+noinline_for_stack i40e_status i40e_update_link_info(struct i40e_hw *hw)
 {
 	struct i40e_aq_get_phy_abilities_resp abilities;
 	i40e_status status = 0;
-- 
2.20.1

[Intel-wired-lan] [PATCH AUTOSEL 4.19 543/671] ixgbe: sync the first fragment unconditionally

[Sasha Levin]

From: Firo Yang <firo.yang@suse.com>

[ Upstream commit e7ba676c6188d394a0133fc4b9bcd7ee50d54b7f ]

In Xen environment, if Xen-swiotlb is enabled, ixgbe driver
could possibly allocate a page, DMA memory buffer, for the first
fragment which is not suitable for Xen-swiotlb to do DMA operations.
Xen-swiotlb have to internally allocate another page for doing DMA
operations. This mechanism requires syncing the data from the internal
page to the page which ixgbe sends to upper network stack. However,
since commit f3213d932173 ("ixgbe: Update driver to make use of DMA
attributes in Rx path"), the unmap operation is performed with
DMA_ATTR_SKIP_CPU_SYNC. As a result, the sync is not performed.
Since the sync isn't performed, the upper network stack could receive
a incomplete network packet. By incomplete, it means the linear data
on the first fragment(between skb->head and skb->end) is invalid. So
we have to copy the data from the internal xen-swiotlb page to the page
which ixgbe sends to upper network stack through the sync operation.

More details from Alexander Duyck:
Specifically since we are mapping the frame with
DMA_ATTR_SKIP_CPU_SYNC we have to unmap with that as well. As a result
a sync is not performed on an unmap and must be done manually as we
skipped it for the first frag. As such we need to always sync before
possibly performing a page unmap operation.

Fixes: f3213d932173 ("ixgbe: Update driver to make use of DMA attributes in Rx path")
Signed-off-by: Firo Yang <firo.yang@suse.com>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index de65ca1e6558..51cd58fbab69 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -1822,13 +1822,7 @@ static void ixgbe_pull_tail(struct ixgbe_ring *rx_ring,
 static void ixgbe_dma_sync_frag(struct ixgbe_ring *rx_ring,
 				struct sk_buff *skb)
 {
-	/* if the page was released unmap it, else just sync our portion */
-	if (unlikely(IXGBE_CB(skb)->page_released)) {
-		dma_unmap_page_attrs(rx_ring->dev, IXGBE_CB(skb)->dma,
-				     ixgbe_rx_pg_size(rx_ring),
-				     DMA_FROM_DEVICE,
-				     IXGBE_RX_DMA_ATTR);
-	} else if (ring_uses_build_skb(rx_ring)) {
+	if (ring_uses_build_skb(rx_ring)) {
 		unsigned long offset = (unsigned long)(skb->data) & ~PAGE_MASK;
 
 		dma_sync_single_range_for_cpu(rx_ring->dev,
@@ -1845,6 +1839,14 @@ static void ixgbe_dma_sync_frag(struct ixgbe_ring *rx_ring,
 					      skb_frag_size(frag),
 					      DMA_FROM_DEVICE);
 	}
+
+	/* If the page was released, just unmap it. */
+	if (unlikely(IXGBE_CB(skb)->page_released)) {
+		dma_unmap_page_attrs(rx_ring->dev, IXGBE_CB(skb)->dma,
+				     ixgbe_rx_pg_size(rx_ring),
+				     DMA_FROM_DEVICE,
+				     IXGBE_RX_DMA_ATTR);
+	}
 }
 
 /**
-- 
2.20.1