On Thursday 16 September 2010 20:32:36 Jens Axboe wrote:
On 2010-09-16 16:49, Steven Rostedt wrote:
Git blame shows this to be your code (copied from block/blktrace.c from years past).
Is the lock_kernel() needed here? (although Arnd did add it in 62c2a7d9)
It isn't, it can be removed.
Ok, I queued up this patch now. Thanks!
Arnd --- Subject: [PATCH] blktrace: remove the big kernel lock
According to Jens, this code does not need the BKL at all, it is sufficiently serialized by bd_mutex.
Signed-off-by: Arnd Bergmann arnd@arndb.de Cc: Jens Axboe jaxboe@fusionio.com Cc: Steven Rostedt rostedt@goodmis.org
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index 959f8d6..5328e87 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -23,7 +23,6 @@ #include <linux/mutex.h> #include <linux/slab.h> #include <linux/debugfs.h> -#include <linux/smp_lock.h> #include <linux/time.h> #include <linux/uaccess.h>
@@ -639,7 +638,6 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg) if (!q) return -ENXIO;
- lock_kernel(); mutex_lock(&bdev->bd_mutex);
switch (cmd) { @@ -667,7 +665,6 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg) }
mutex_unlock(&bdev->bd_mutex); - unlock_kernel(); return ret; }
@@ -1652,10 +1649,9 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev, struct block_device *bdev; ssize_t ret = -ENXIO;
- lock_kernel(); bdev = bdget(part_devt(p)); if (bdev == NULL) - goto out_unlock_kernel; + goto out;
q = blk_trace_get_queue(bdev); if (q == NULL) @@ -1683,8 +1679,7 @@ out_unlock_bdev: mutex_unlock(&bdev->bd_mutex); out_bdput: bdput(bdev); -out_unlock_kernel: - unlock_kernel(); +out: return ret; }
@@ -1714,11 +1709,10 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
ret = -ENXIO;
- lock_kernel(); p = dev_to_part(dev); bdev = bdget(part_devt(p)); if (bdev == NULL) - goto out_unlock_kernel; + goto out;
q = blk_trace_get_queue(bdev); if (q == NULL) @@ -1753,8 +1747,6 @@ out_unlock_bdev: mutex_unlock(&bdev->bd_mutex); out_bdput: bdput(bdev); -out_unlock_kernel: - unlock_kernel(); out: return ret ? ret : count; }