[PATCH net-next 7/7] wifi: mt76: move napi

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* [PATCH net-next 7/7] wifi: mt76: move napi_enable() from under BH
       [not found] <20250121221519.392014-1-kuba@kernel.org>
@ 2025-01-21 22:15 ` Jakub Kicinski
  2025-01-22 14:25   ` Eric Dumazet
  0 siblings, 1 reply; 3+ messages in thread
From: Jakub Kicinski @ 2025-01-21 22:15 UTC (permalink / raw)
  To: davem
  Cc: netdev, edumazet, pabeni, andrew+netdev, horms, dan.carpenter,
	Jakub Kicinski, nbd, lorenzo, ryder.lee, shayne.chen, sean.wang,
	kvalo, matthias.bgg, angelogioacchino.delregno, quan.zhou,
	johannes.berg, emmanuel.grumbach, leitao, mingyen.hsieh, leon.yen,
	deren.wu, chui-hao.chiu, kuniyu, romieu, linux-wireless

mt76 does a lot of:

  local_bh_disable();
  napi_enable(...napi);
  napi_schedule(...napi);
  local_bh_enable();

local_bh_disable() is not a real lock, its most likely taken
because napi_schedule() requires it. napi_enable() needs
to take a mutex, so move it from under the BH protection.

Fixes: 413f0271f396 ("net: protect NAPI enablement with netdev_lock()")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/dcfd56bc-de32-4b11-9e19-d8bd1543745d@stanley.mountain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: nbd@nbd.name
CC: lorenzo@kernel.org
CC: ryder.lee@mediatek.com
CC: shayne.chen@mediatek.com
CC: sean.wang@mediatek.com
CC: kvalo@kernel.org
CC: matthias.bgg@gmail.com
CC: angelogioacchino.delregno@collabora.com
CC: quan.zhou@mediatek.com
CC: johannes.berg@intel.com
CC: emmanuel.grumbach@intel.com
CC: leitao@debian.org
CC: mingyen.hsieh@mediatek.com
CC: leon.yen@mediatek.com
CC: deren.wu@mediatek.com
CC: chui-hao.chiu@mediatek.com
CC: kuniyu@amazon.com
CC: romieu@fr.zoreil.com
CC: linux-wireless@vger.kernel.org
---
 drivers/net/wireless/mediatek/mt76/mt7603/mac.c |  9 ++++-----
 drivers/net/wireless/mediatek/mt76/mt7615/pci.c |  8 ++++++--
 .../net/wireless/mediatek/mt76/mt7615/pci_mac.c |  8 +++++---
 drivers/net/wireless/mediatek/mt76/mt76x0/pci.c |  8 +++++---
 .../net/wireless/mediatek/mt76/mt76x02_mmio.c   |  8 +++++---
 drivers/net/wireless/mediatek/mt76/mt76x2/pci.c |  7 +++++--
 drivers/net/wireless/mediatek/mt76/mt7915/mac.c | 17 +++++++++++++----
 drivers/net/wireless/mediatek/mt76/mt7921/pci.c |  7 +++++--
 .../net/wireless/mediatek/mt76/mt7921/pci_mac.c |  7 +++++--
 drivers/net/wireless/mediatek/mt76/mt7925/pci.c |  7 +++++--
 .../net/wireless/mediatek/mt76/mt7925/pci_mac.c |  7 +++++--
 drivers/net/wireless/mediatek/mt76/mt7996/mac.c | 12 ++++++------
 12 files changed, 69 insertions(+), 36 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7603/mac.c b/drivers/net/wireless/mediatek/mt76/mt7603/mac.c
index a259f4dd9540..413973d05b43 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7603/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7603/mac.c
@@ -1479,14 +1479,13 @@ static void mt7603_mac_watchdog_reset(struct mt7603_dev *dev)
 	tasklet_enable(&dev->mt76.pre_tbtt_tasklet);
 	mt7603_beacon_set_timer(dev, -1, beacon_int);
 
-	local_bh_disable();
 	napi_enable(&dev->mt76.tx_napi);
-	napi_schedule(&dev->mt76.tx_napi);
-
 	napi_enable(&dev->mt76.napi[0]);
-	napi_schedule(&dev->mt76.napi[0]);
-
 	napi_enable(&dev->mt76.napi[1]);
+
+	local_bh_disable();
+	napi_schedule(&dev->mt76.tx_napi);
+	napi_schedule(&dev->mt76.napi[0]);
 	napi_schedule(&dev->mt76.napi[1]);
 	local_bh_enable();
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/pci.c b/drivers/net/wireless/mediatek/mt76/mt7615/pci.c
index 9a278589df4e..68010e27f065 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/pci.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/pci.c
@@ -164,12 +164,16 @@ static int mt7615_pci_resume(struct pci_dev *pdev)
 		dev_err(mdev->dev, "PDMA engine must be reinitialized\n");
 
 	mt76_worker_enable(&mdev->tx_worker);
-	local_bh_disable();
+
 	mt76_for_each_q_rx(mdev, i) {
 		napi_enable(&mdev->napi[i]);
-		napi_schedule(&mdev->napi[i]);
 	}
 	napi_enable(&mdev->tx_napi);
+
+	local_bh_disable();
+	mt76_for_each_q_rx(mdev, i) {
+		napi_schedule(&mdev->napi[i]);
+	}
 	napi_schedule(&mdev->tx_napi);
 	local_bh_enable();
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/pci_mac.c b/drivers/net/wireless/mediatek/mt76/mt7615/pci_mac.c
index a0ca3bbdfcaf..c2e4e6aabd9f 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7615/pci_mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7615/pci_mac.c
@@ -262,12 +262,14 @@ void mt7615_mac_reset_work(struct work_struct *work)
 
 	mt76_worker_enable(&dev->mt76.tx_worker);
 
-	local_bh_disable();
 	napi_enable(&dev->mt76.tx_napi);
-	napi_schedule(&dev->mt76.tx_napi);
-
 	mt76_for_each_q_rx(&dev->mt76, i) {
 		napi_enable(&dev->mt76.napi[i]);
+	}
+
+	local_bh_disable();
+	napi_schedule(&dev->mt76.tx_napi);
+	mt76_for_each_q_rx(&dev->mt76, i) {
 		napi_schedule(&dev->mt76.napi[i]);
 	}
 	local_bh_enable();
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x0/pci.c b/drivers/net/wireless/mediatek/mt76/mt76x0/pci.c
index 1eb955f3ca13..b456ccd00d58 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x0/pci.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x0/pci.c
@@ -282,14 +282,16 @@ static int mt76x0e_resume(struct pci_dev *pdev)
 
 	mt76_worker_enable(&mdev->tx_worker);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(mdev, i) {
 		mt76_queue_rx_reset(dev, i);
 		napi_enable(&mdev->napi[i]);
+	}
+	napi_enable(&mdev->tx_napi);
+
+	local_bh_disable();
+	mt76_for_each_q_rx(mdev, i) {
 		napi_schedule(&mdev->napi[i]);
 	}
-
-	napi_enable(&mdev->tx_napi);
 	napi_schedule(&mdev->tx_napi);
 	local_bh_enable();
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c b/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c
index 7d840ad4ae65..a82c75ba26e6 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x02_mmio.c
@@ -504,12 +504,14 @@ static void mt76x02_watchdog_reset(struct mt76x02_dev *dev)
 	mt76_worker_enable(&dev->mt76.tx_worker);
 	tasklet_enable(&dev->mt76.pre_tbtt_tasklet);
 
-	local_bh_disable();
 	napi_enable(&dev->mt76.tx_napi);
-	napi_schedule(&dev->mt76.tx_napi);
-
 	mt76_for_each_q_rx(&dev->mt76, i) {
 		napi_enable(&dev->mt76.napi[i]);
+	}
+
+	local_bh_disable();
+	napi_schedule(&dev->mt76.tx_napi);
+	mt76_for_each_q_rx(&dev->mt76, i) {
 		napi_schedule(&dev->mt76.napi[i]);
 	}
 	local_bh_enable();
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c b/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
index 67c9d1caa0bd..727bfdd00b40 100644
--- a/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2/pci.c
@@ -151,12 +151,15 @@ mt76x2e_resume(struct pci_dev *pdev)
 
 	mt76_worker_enable(&mdev->tx_worker);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(mdev, i) {
 		napi_enable(&mdev->napi[i]);
-		napi_schedule(&mdev->napi[i]);
 	}
 	napi_enable(&mdev->tx_napi);
+
+	local_bh_disable();
+	mt76_for_each_q_rx(mdev, i) {
+		napi_schedule(&mdev->napi[i]);
+	}
 	napi_schedule(&mdev->tx_napi);
 	local_bh_enable();
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mac.c b/drivers/net/wireless/mediatek/mt76/mt7915/mac.c
index 13bdc0a7174c..2ba6eb3038ce 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/mac.c
@@ -1356,10 +1356,15 @@ mt7915_mac_restart(struct mt7915_dev *dev)
 
 	mt7915_dma_reset(dev, true);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(mdev, i) {
 		if (mdev->q_rx[i].ndesc) {
 			napi_enable(&dev->mt76.napi[i]);
+		}
+	}
+
+	local_bh_disable();
+	mt76_for_each_q_rx(mdev, i) {
+		if (mdev->q_rx[i].ndesc) {
 			napi_schedule(&dev->mt76.napi[i]);
 		}
 	}
@@ -1419,8 +1424,9 @@ mt7915_mac_restart(struct mt7915_dev *dev)
 	if (phy2)
 		clear_bit(MT76_RESET, &phy2->mt76->state);
 
-	local_bh_disable();
 	napi_enable(&dev->mt76.tx_napi);
+
+	local_bh_disable();
 	napi_schedule(&dev->mt76.tx_napi);
 	local_bh_enable();
 
@@ -1570,9 +1576,12 @@ void mt7915_mac_reset_work(struct work_struct *work)
 	if (phy2)
 		clear_bit(MT76_RESET, &phy2->mt76->state);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(&dev->mt76, i) {
 		napi_enable(&dev->mt76.napi[i]);
+	}
+
+	local_bh_disable();
+	mt76_for_each_q_rx(&dev->mt76, i) {
 		napi_schedule(&dev->mt76.napi[i]);
 	}
 	local_bh_enable();
@@ -1581,8 +1590,8 @@ void mt7915_mac_reset_work(struct work_struct *work)
 
 	mt76_worker_enable(&dev->mt76.tx_worker);
 
-	local_bh_disable();
 	napi_enable(&dev->mt76.tx_napi);
+	local_bh_disable();
 	napi_schedule(&dev->mt76.tx_napi);
 	local_bh_enable();
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
index ba870e1b05fb..a0c9df3c2cc7 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/pci.c
@@ -523,12 +523,15 @@ static int mt7921_pci_resume(struct device *device)
 
 	mt76_worker_enable(&mdev->tx_worker);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(mdev, i) {
 		napi_enable(&mdev->napi[i]);
-		napi_schedule(&mdev->napi[i]);
 	}
 	napi_enable(&mdev->tx_napi);
+
+	local_bh_disable();
+	mt76_for_each_q_rx(mdev, i) {
+		napi_schedule(&mdev->napi[i]);
+	}
 	napi_schedule(&mdev->tx_napi);
 	local_bh_enable();
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/pci_mac.c b/drivers/net/wireless/mediatek/mt76/mt7921/pci_mac.c
index 2452b1a2d118..881812ba03ff 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/pci_mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/pci_mac.c
@@ -81,9 +81,12 @@ int mt7921e_mac_reset(struct mt792x_dev *dev)
 
 	mt792x_wpdma_reset(dev, true);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(&dev->mt76, i) {
 		napi_enable(&dev->mt76.napi[i]);
+	}
+
+	local_bh_disable();
+	mt76_for_each_q_rx(&dev->mt76, i) {
 		napi_schedule(&dev->mt76.napi[i]);
 	}
 	local_bh_enable();
@@ -115,8 +118,8 @@ int mt7921e_mac_reset(struct mt792x_dev *dev)
 	err = __mt7921_start(&dev->phy);
 out:
 
-	local_bh_disable();
 	napi_enable(&dev->mt76.tx_napi);
+	local_bh_disable();
 	napi_schedule(&dev->mt76.tx_napi);
 	local_bh_enable();
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/pci.c b/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
index f36893e20c61..c7b5dc1dbb34 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/pci.c
@@ -556,12 +556,15 @@ static int mt7925_pci_resume(struct device *device)
 
 	mt76_worker_enable(&mdev->tx_worker);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(mdev, i) {
 		napi_enable(&mdev->napi[i]);
-		napi_schedule(&mdev->napi[i]);
 	}
 	napi_enable(&mdev->tx_napi);
+
+	local_bh_disable();
+	mt76_for_each_q_rx(mdev, i) {
+		napi_schedule(&mdev->napi[i]);
+	}
 	napi_schedule(&mdev->tx_napi);
 	local_bh_enable();
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/pci_mac.c b/drivers/net/wireless/mediatek/mt76/mt7925/pci_mac.c
index faedbf766d1a..4578d16bf456 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/pci_mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/pci_mac.c
@@ -101,12 +101,15 @@ int mt7925e_mac_reset(struct mt792x_dev *dev)
 
 	mt792x_wpdma_reset(dev, true);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(&dev->mt76, i) {
 		napi_enable(&dev->mt76.napi[i]);
-		napi_schedule(&dev->mt76.napi[i]);
 	}
 	napi_enable(&dev->mt76.tx_napi);
+
+	local_bh_disable();
+	mt76_for_each_q_rx(&dev->mt76, i) {
+		napi_schedule(&dev->mt76.napi[i]);
+	}
 	napi_schedule(&dev->mt76.tx_napi);
 	local_bh_enable();
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
index bc8cba4dca47..019c925ae600 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mac.c
@@ -1695,7 +1695,6 @@ mt7996_mac_restart(struct mt7996_dev *dev)
 
 	mt7996_dma_reset(dev, true);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(mdev, i) {
 		if (mtk_wed_device_active(&dev->mt76.mmio.wed) &&
 		    mt76_queue_is_wed_rro(&mdev->q_rx[i]))
@@ -1703,10 +1702,11 @@ mt7996_mac_restart(struct mt7996_dev *dev)
 
 		if (mdev->q_rx[i].ndesc) {
 			napi_enable(&dev->mt76.napi[i]);
+			local_bh_disable();
 			napi_schedule(&dev->mt76.napi[i]);
+			local_bh_enable();
 		}
 	}
-	local_bh_enable();
 	clear_bit(MT76_MCU_RESET, &dev->mphy.state);
 	clear_bit(MT76_STATE_MCU_RUNNING, &dev->mphy.state);
 
@@ -1764,8 +1764,8 @@ mt7996_mac_restart(struct mt7996_dev *dev)
 	if (phy3)
 		clear_bit(MT76_RESET, &phy3->mt76->state);
 
-	local_bh_disable();
 	napi_enable(&dev->mt76.tx_napi);
+	local_bh_disable();
 	napi_schedule(&dev->mt76.tx_napi);
 	local_bh_enable();
 
@@ -1958,23 +1958,23 @@ void mt7996_mac_reset_work(struct work_struct *work)
 	if (phy3)
 		clear_bit(MT76_RESET, &phy3->mt76->state);
 
-	local_bh_disable();
 	mt76_for_each_q_rx(&dev->mt76, i) {
 		if (mtk_wed_device_active(&dev->mt76.mmio.wed) &&
 		    mt76_queue_is_wed_rro(&dev->mt76.q_rx[i]))
 			continue;
 
 		napi_enable(&dev->mt76.napi[i]);
+		local_bh_disable();
 		napi_schedule(&dev->mt76.napi[i]);
+		local_bh_enable();
 	}
-	local_bh_enable();
 
 	tasklet_schedule(&dev->mt76.irq_tasklet);
 
 	mt76_worker_enable(&dev->mt76.tx_worker);
 
-	local_bh_disable();
 	napi_enable(&dev->mt76.tx_napi);
+	local_bh_disable();
 	napi_schedule(&dev->mt76.tx_napi);
 	local_bh_enable();
 
-- 
2.48.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread

* Re: [PATCH net-next 7/7] wifi: mt76: move napi_enable() from under BH
  2025-01-21 22:15 ` [PATCH net-next 7/7] wifi: mt76: move napi_enable() from under BH Jakub Kicinski
@ 2025-01-22 14:25   ` Eric Dumazet
  2025-01-22 14:36     ` Jakub Kicinski
  0 siblings, 1 reply; 3+ messages in thread
From: Eric Dumazet @ 2025-01-22 14:25 UTC (permalink / raw)
  To: Jakub Kicinski
  Cc: davem, netdev, pabeni, andrew+netdev, horms, dan.carpenter, nbd,
	lorenzo, ryder.lee, shayne.chen, sean.wang, kvalo, matthias.bgg,
	angelogioacchino.delregno, quan.zhou, johannes.berg,
	emmanuel.grumbach, leitao, mingyen.hsieh, leon.yen, deren.wu,
	chui-hao.chiu, kuniyu, romieu, linux-wireless

On Tue, Jan 21, 2025 at 11:15 PM Jakub Kicinski <kuba@kernel.org> wrote:
>
> mt76 does a lot of:
>
>   local_bh_disable();
>   napi_enable(...napi);
>   napi_schedule(...napi);
>   local_bh_enable();
>
> local_bh_disable() is not a real lock, its most likely taken
> because napi_schedule() requires it. napi_enable() needs
> to take a mutex, so move it from under the BH protection.
>
> Fixes: 413f0271f396 ("net: protect NAPI enablement with netdev_lock()")
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Link: https://lore.kernel.org/dcfd56bc-de32-4b11-9e19-d8bd1543745d@stanley.mountain
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Reviewed-by: Eric Dumazet <edumazet@google.com>

napi_schedule() can run from arbitrary contexts though...

BH protection seems strange to me, but this is orthogonal to your fix.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH net-next 7/7] wifi: mt76: move napi_enable() from under BH
  2025-01-22 14:25   ` Eric Dumazet
@ 2025-01-22 14:36     ` Jakub Kicinski
  0 siblings, 0 replies; 3+ messages in thread
From: Jakub Kicinski @ 2025-01-22 14:36 UTC (permalink / raw)
  To: Eric Dumazet
  Cc: davem, netdev, pabeni, andrew+netdev, horms, dan.carpenter, nbd,
	lorenzo, ryder.lee, shayne.chen, sean.wang, kvalo, matthias.bgg,
	angelogioacchino.delregno, quan.zhou, johannes.berg,
	emmanuel.grumbach, leitao, mingyen.hsieh, leon.yen, deren.wu,
	chui-hao.chiu, kuniyu, romieu, linux-wireless

On Wed, 22 Jan 2025 15:25:46 +0100 Eric Dumazet wrote:
> napi_schedule() can run from arbitrary contexts though...
> 
> BH protection seems strange to me, but this is orthogonal to your fix.

Right, it doesn't need the BH "protection", it's just what we 
do to make sure there is a softirq hook point after we call it.
Since local_irq_restore() does not call softirqs. 

I didn't know how to express that in a way that would be understandable
for most :S

Thanks for catching the other bug!

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2025-01-22 14:36 UTC | newest]

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     [not found] <20250121221519.392014-1-kuba@kernel.org>
2025-01-21 22:15 ` [PATCH net-next 7/7] wifi: mt76: move napi_enable() from under BH Jakub Kicinski
2025-01-22 14:25   ` Eric Dumazet
2025-01-22 14:36     ` Jakub Kicinski

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