From: Li Zefan Date: Fri, 20 Mar 2009 02:34:00 +0000 (+0800) Subject: blktrace: avoid accessing NULL bdev->bd_disk X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=b125130b22d67f249beba10b71a254558b5279d0;p=linux-2.6-omap-h63xx.git blktrace: avoid accessing NULL bdev->bd_disk bdev->bd_disk can be NULL, if the block device is not opened. Try this against an unmounted partition, and you'll see NULL dereference: # echo 1 > /sys/block/sda/sda5/enable Signed-off-by: Li Zefan Acked-by: Frederic Weisbecker Acked-by: Arnaldo Carvalho de Melo Cc: Jens Axboe Cc: Steven Rostedt LKML-Reference: <49C30098.6080107@cn.fujitsu.com> Signed-off-by: Ingo Molnar --- diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index dfee6f91517..108f4f7715a 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -1362,6 +1362,14 @@ static int blk_str2act_mask(const char *str) return mask; } +static struct request_queue *blk_trace_get_queue(struct block_device *bdev) +{ + if (bdev->bd_disk == NULL) + return NULL; + + return bdev_get_queue(bdev); +} + static ssize_t sysfs_blk_trace_attr_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -1376,9 +1384,10 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev, if (bdev == NULL) goto out_unlock_kernel; - q = bdev_get_queue(bdev); + q = blk_trace_get_queue(bdev); if (q == NULL) goto out_bdput; + mutex_lock(&bdev->bd_mutex); if (attr == &dev_attr_enable) { @@ -1435,7 +1444,7 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev, if (bdev == NULL) goto out_unlock_kernel; - q = bdev_get_queue(bdev); + q = blk_trace_get_queue(bdev); if (q == NULL) goto out_bdput;