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authorAndrea Merello <andrea.merello@gmail.com>2017-07-08 10:11:11 +0200
committerMathias Kresin <dev@kresin.me>2017-07-20 19:10:29 +0200
commitb81c04382b5ddea0164993c2af0df7270bb95ee4 (patch)
tree0d277e90337a8c8ef304da6e6c93ef0c376510aa /target/linux/lantiq/patches-4.9
parent34c01e68b5d6b06ce3794ef0e2b06e81ec3ce8ca (diff)
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lantiq: fix sleep with spinlock held in xrx200 network driver
In the xrx200_close() function we call napi_disable(), that could sleep, with priv->hw->chan[i].lock held. This could lead to deadlock and causes the kernel to complain. Look at the code I couldn't convince myself about why we need to protect that specific code part with the lock. IMHO there seems no reason to protect the refcount variables, because AFAIK ndo_close() and ndo_open() callbacks are already called with a semaphore held. Neither I could figure out why napi_disable() have to be called with that lock held. The only remaining code part for which I could guess the lock is useful for is ltq_dma_close() function call. This patch reduces the lock to the said function call, avoiding the sleep-with-spinlock-held situation Signed-off-by: Andrea Merello <andrea.merello@gmail.com> [fold into 0025-NET-MIPS-lantiq-adds-xrx200-net.patch, backport to kernel 4.4] Signed-off-by: Mathias Kresin <dev@kresin.me>
Diffstat (limited to 'target/linux/lantiq/patches-4.9')
-rw-r--r--target/linux/lantiq/patches-4.9/0025-NET-MIPS-lantiq-adds-xrx200-net.patch7
1 files changed, 4 insertions, 3 deletions
diff --git a/target/linux/lantiq/patches-4.9/0025-NET-MIPS-lantiq-adds-xrx200-net.patch b/target/linux/lantiq/patches-4.9/0025-NET-MIPS-lantiq-adds-xrx200-net.patch
index 80bcea0f4b..871176449c 100644
--- a/target/linux/lantiq/patches-4.9/0025-NET-MIPS-lantiq-adds-xrx200-net.patch
+++ b/target/linux/lantiq/patches-4.9/0025-NET-MIPS-lantiq-adds-xrx200-net.patch
@@ -209,7 +209,7 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
+};
--- /dev/null
+++ b/drivers/net/ethernet/lantiq_xrx200.c
-@@ -0,0 +1,1851 @@
+@@ -0,0 +1,1852 @@
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
@@ -1110,14 +1110,15 @@ Subject: [PATCH 25/36] NET: MIPS: lantiq: adds xrx200-net
+ for (i = 0; i < XRX200_MAX_DMA; i++) {
+ if (!priv->hw->chan[i].dma.irq)
+ continue;
-+ spin_lock_bh(&priv->hw->chan[i].lock);
++
+ priv->hw->chan[i].refcount--;
+ if (!priv->hw->chan[i].refcount) {
+ if (XRX200_DMA_IS_RX(i))
+ napi_disable(&priv->hw->chan[i].napi);
++ spin_lock_bh(&priv->hw->chan[i].lock);
+ ltq_dma_close(&priv->hw->chan[XRX200_DMA_RX].dma);
++ spin_unlock_bh(&priv->hw->chan[i].lock);
+ }
-+ spin_unlock_bh(&priv->hw->chan[i].lock);
+ }
+
+ return 0;