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Subject[PATCH] net: via-velocity.c fix sleep-with-spinlock bug during MTU change

From: Arjan van de Ven <arjan@linux.intel.com>
Subject: [PATCH] net: via-velocity.c fix sleep-with-spinlock bug during MTU change

The via-velocity.c driver reinitializes (frees/allocates) several
metadata structures during an MTU change. Unfortunately the allocations
of the new versions of the metadata is done with GFP_KERNEL, even
though this change of datastructures is (and needs to be) done while
holding a spinlock (with irqs off).

Clearly that isn't a good thing, and kerneloops.org has trapped a large
deal of the resulting warnings. The fix is to use GFP_ATOMIC.
While not elegant, avoiding the lock is going to be extremely complex.
In addition, this is a "static", long lived allocation (after all, how
often do you actually change your mtu) and not something that happens
on an ongoing basis.

Reported-by: www.kerneloops.org
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
drivers/net/via-velocity.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/net/via-velocity.c b/drivers/net/via-velocity.c
index 6b8d882..4bf08fd 100644
--- a/drivers/net/via-velocity.c
+++ b/drivers/net/via-velocity.c
@@ -1,4 +1,4 @@
-/*
+;/*
* This code is derived from the VIA reference driver (copyright message
* below) provided to Red Hat by VIA Networking Technologies, Inc. for
* addition to the Linux kernel.
@@ -1241,6 +1241,9 @@ static int velocity_rx_refill(struct velocity_info *vptr)
*
* Allocate and set up the receive buffers for each ring slot and
* assign them to the network adapter.
+ *
+ * Note: This function gets called with irqs off/lock held
+ * from velocity_change_mtu()
*/

static int velocity_init_rd_ring(struct velocity_info *vptr)
@@ -1251,7 +1254,7 @@ static int velocity_init_rd_ring(struct velocity_info *vptr)
vptr->rx_buf_sz = (mtu <= ETH_DATA_LEN) ? PKT_BUF_SZ : mtu + 32;

vptr->rd_info = kcalloc(vptr->options.numrx,
- sizeof(struct velocity_rd_info), GFP_KERNEL);
+ sizeof(struct velocity_rd_info), GFP_ATOMIC);
if (!vptr->rd_info)
return -ENOMEM;

@@ -1309,6 +1312,9 @@ static void velocity_free_rd_ring(struct velocity_info *vptr)
* Set up the transmit ring and chain the ring pointers together.
* Returns zero on success or a negative posix errno code for
* failure.
+ *
+ * Note: This function gets called with irqs off/lock held
+ * from velocity_change_mtu()
*/

static int velocity_init_td_ring(struct velocity_info *vptr)
@@ -1324,7 +1330,7 @@ static int velocity_init_td_ring(struct velocity_info *vptr)

vptr->td_infos[j] = kcalloc(vptr->options.numtx,
sizeof(struct velocity_td_info),
- GFP_KERNEL);
+ GFP_ATOMIC);
if (!vptr->td_infos[j]) {
while(--j >= 0)
kfree(vptr->td_infos[j]);
--
1.5.5.1

--
If you want to reach me at my work email, use arjan@linux.intel.com
For development, discussion and tips for power savings,
visit http://www.lesswatts.org


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