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@xxxxxxxx>
Cc: Jens Axboe <jaxboe@xxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
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;
}
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