diff options
| author | Shaun Ruffell <sruffell@digium.com> | 2009-12-17 18:00:36 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-01-06 15:03:51 -0800 |
| commit | 120dbaa5f31dfea13be03da90d90dc2cfed77841 (patch) | |
| tree | 711b96e5bb2c61ddb2b3f693ec4e31c426b07a91 /lib | |
| parent | c4ddbba638a74b9110801026517e892e5a8db6ad (diff) | |
| download | lwn-120dbaa5f31dfea13be03da90d90dc2cfed77841.tar.gz lwn-120dbaa5f31dfea13be03da90d90dc2cfed77841.zip | |
dma-debug: Do not add notifier when dma debugging is disabled.
commit f797d9881b62c2ddb1d2e7bd80d87141949c84aa upstream.
If CONFIG_HAVE_DMA_API_DEBUG is defined and "dma_debug=off" is
specified on the kernel command line, when you detach a driver from a
device you can cause the following NULL pointer dereference:
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<c0580d35>] dma_debug_device_change+0x5d/0x117
The problem is that the dma_debug_device_change notifier function is
added to the bus notifier chain even though the dma_entry_hash array
was never initialized. If dma debugging is disabled, this patch both
prevents dma_debug_device_change notifiers from being added to the
chain, and additionally ensures that the dma_debug_device_change
notifier function is a no-op.
Signed-off-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/dma-debug.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/lib/dma-debug.c b/lib/dma-debug.c index ce6b7eabf674..dcd43e30968e 100644 --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -676,6 +676,8 @@ static int dma_debug_device_change(struct notifier_block *nb, struct device *dev = data; int count; + if (global_disable) + return; switch (action) { case BUS_NOTIFY_UNBOUND_DRIVER: @@ -697,6 +699,9 @@ void dma_debug_add_bus(struct bus_type *bus) { struct notifier_block *nb; + if (global_disable) + return; + nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL); if (nb == NULL) { pr_err("dma_debug_add_bus: out of memory\n"); |