Remove explicit lock_kernel() calls and document why the code is safe.
Signed-off-by: Roland Dreier <[EMAIL PROTECTED]>
---
Hi Jon, more BKL removal for your tree. Should be ready for 2.6.27.
diff --git a/drivers/infiniband/core/user_mad.c
b/drivers/infiniband/core/user_mad.c
index 260b3df..d31e5bb 100644
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -47,7 +47,6 @@
#include <linux/kref.h>
#include <linux/compat.h>
#include <linux/semaphore.h>
-#include <linux/smp_lock.h>
#include <asm/uaccess.h>
@@ -778,23 +777,33 @@ static long ib_umad_compat_ioctl(struct file *filp,
unsigned int cmd,
}
#endif
+/*
+ * ib_umad_open() does not need the BKL:
+ *
+ * - umad_port[] accesses are protected by port_lock, the
+ * ib_umad_port 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;
+ * - the ioctl method does not affect any global state outside of the
+ * file structure being operated on;
+ * - the port is added to umad_port[] as the last part of module
+ * initialization so the open method will either immediately run
+ * -ENXIO, or all required initialization will be done.
+ */
static int ib_umad_open(struct inode *inode, struct file *filp)
{
struct ib_umad_port *port;
struct ib_umad_file *file;
int ret = 0;
- lock_kernel();
spin_lock(&port_lock);
port = umad_port[iminor(inode) - IB_UMAD_MINOR_BASE];
if (port)
kref_get(&port->umad_dev->ref);
spin_unlock(&port_lock);
- if (!port) {
- unlock_kernel();
+ if (!port)
return -ENXIO;
- }
mutex_lock(&port->file_mutex);
@@ -823,7 +832,6 @@ static int ib_umad_open(struct inode *inode, struct file
*filp)
out:
mutex_unlock(&port->file_mutex);
- unlock_kernel();
return ret;
}
_______________________________________________
general mailing list
[email protected]
http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general
To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
