Remove explicit lock_kernel() calls and document why the code is safe.
Signed-off-by: Roland Dreier <[EMAIL PROTECTED]>
---
Hi Jon,
Is this sort of patch the next step in the BKL-removal plan? Is now an
appropriate time to send such things?
If this looks good to you I will do a careful audit of the rest of
drivers/infiniband/core and send you a few more similar patches.
Thanks,
Roland
drivers/infiniband/core/uverbs_main.c | 20 +++++++++++++-------
1 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/drivers/infiniband/core/uverbs_main.c
b/drivers/infiniband/core/uverbs_main.c
index f839dde..661b3f8 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -45,7 +45,6 @@
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/cdev.h>
-#include <linux/smp_lock.h>
#include <asm/uaccess.h>
@@ -611,23 +610,32 @@ static int ib_uverbs_mmap(struct file *filp, struct
vm_area_struct *vma)
return file->device->ib_dev->mmap(file->ucontext, vma);
}
+/*
+ * ib_uverbs_open() does not need the BKL:
+ *
+ * - dev_table[] accesses are protected by map_lock, the
+ * ib_uverbs_device structures are properly reference counted, and
+ * everything else is purely local to the file being created, so
+ * races against other open calls are not a proble;
+ * - there is no ioctl method to race against;
+ * - the device is added to dev_table[] as the last part of module
+ * initialization, the open method will either immediately run
+ * -ENXIO, or all required initialization will be done.
+ */
static int ib_uverbs_open(struct inode *inode, struct file *filp)
{
struct ib_uverbs_device *dev;
struct ib_uverbs_file *file;
int ret;
- lock_kernel();
spin_lock(&map_lock);
dev = dev_table[iminor(inode) - IB_UVERBS_BASE_MINOR];
if (dev)
kref_get(&dev->ref);
spin_unlock(&map_lock);
- if (!dev) {
- unlock_kernel();
+ if (!dev)
return -ENXIO;
- }
if (!try_module_get(dev->ib_dev->owner)) {
ret = -ENODEV;
@@ -648,7 +656,6 @@ static int ib_uverbs_open(struct inode *inode, struct file
*filp)
filp->private_data = file;
- unlock_kernel();
return 0;
err_module:
@@ -656,7 +663,6 @@ err_module:
err:
kref_put(&dev->ref, ib_uverbs_release_dev);
- unlock_kernel();
return ret;
}
--
1.5.6
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