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authorShaun Ruffell <sruffell@digium.com>2009-12-18 00:00:36 (GMT)
committerJoerg Roedel <joerg.roedel@amd.com>2009-12-21 14:10:12 (GMT)
commitf797d9881b62c2ddb1d2e7bd80d87141949c84aa (patch)
treee52785a6c036130cfbe82b0ad9e5cc364acc7be4 /lib/dma-debug.c
parent55639353a0035052d9ea6cfe4dde0ac7fcbb2c9f (diff)
dma-debug: Do not add notifier when dma debugging is disabled.
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. Cc: stable@kernel.org Signed-off-by: Shaun Ruffell <sruffell@digium.com> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Diffstat (limited to 'lib/dma-debug.c')
-rw-r--r--lib/dma-debug.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index d9b08e0..7399744 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");

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