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Subject[PATCH] i40e: reduce stack usage in i40e_set_fc
Date
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>
---
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 906cf68d3453..7af1b7477140 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_common.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_common.c
@@ -1643,25 +1643,15 @@ 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;
@@ -1677,6 +1667,48 @@ 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);
@@ -1685,31 +1717,10 @@ 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) {
@@ -2537,7 +2548,7 @@ 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;
--
2.20.0
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