net/mpc5200: Fix locking on fec_mpc52xx driver

Browse source

Fix the locking scheme on the fec_mpc52xx driver.  This device can
receive IRQs from three sources; the FEC itself, the tx DMA, and the
rx DMA.  Mutual exclusion was handled by taking a spin_lock() in the
critical regions, but because the handlers are run with IRQs enabled,
spin_lock() is insufficient and the driver can end up interrupting
a critical region anyway from another IRQ.

Asier Llano discovered that this occurs when an error IRQ is raised
in the middle of handling rx irqs which resulted in an sk_buff memory
leak.

In addition, locking is spotty at best in the driver and inspection
revealed quite a few places with insufficient locking.

This patch is based on Asier's initial work, but reworks a number of
things so that locks are held for as short a time as possible, so
that spin_lock_irqsave() is used everywhere, and so the locks are
dropped when calling into the network stack (because the lock only
protects the hardware interface; not the network stack).

Boot tested on a lite5200 with an NFS root.  Has not been performance
tested.

Signed-off-by: Asier Llano <a.llano@ziv.es>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

...

This commit is contained in:

Asier Llano 2009-12-08 20:29:10 -08:00 • committed by David S. Miller

parent 4b860abf63

commit 1e4e0767ec

1 changed files with 62 additions and 59 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

121

drivers/net/fec_mpc52xx.c

View file