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| author | Shaun Ruffell <sruffell@digium.com> | 2009-12-17 18:00:36 -0600 |
|---|---|---|
| committer | Joerg Roedel <joerg.roedel@amd.com> | 2009-12-21 15:10:12 +0100 |
| commit | f797d9881b62c2ddb1d2e7bd80d87141949c84aa (patch) | |
| tree | e52785a6c036130cfbe82b0ad9e5cc364acc7be4 /lib/dma-debug.c | |
| parent | 55639353a0035052d9ea6cfe4dde0ac7fcbb2c9f (diff) | |
| download | lwn-f797d9881b62c2ddb1d2e7bd80d87141949c84aa.tar.gz lwn-f797d9881b62c2ddb1d2e7bd80d87141949c84aa.zip | |
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.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/lib/dma-debug.c b/lib/dma-debug.c index d9b08e0f7f55..739974460c32 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"); |