Hi Andrew,

On Oct. Friday 30 (44) 09:41 PM, Andrew Lunn wrote:

On Fri, Oct 30, 2015 at 04:35:42PM -0400, Vivien Didelot wrote:

quoted

It's easy to forget to lock the smi_mutex before calling the low-level
_mv88e6xxx_reg_{read,write}, so add a assert_smi_lock function in them.

Signed-off-by: Vivien Didelot <redacted>
---
 drivers/net/dsa/mv88e6xxx.c | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/drivers/net/dsa/mv88e6xxx.c b/drivers/net/dsa/mv88e6xxx.c
index b1b14f5..70a0106 100644
--- a/drivers/net/dsa/mv88e6xxx.c
+++ b/drivers/net/dsa/mv88e6xxx.c

@@ -24,6 +24,16 @@
 #include <net/switchdev.h>
 #include "mv88e6xxx.h"
 
+static inline void assert_smi_lock(struct dsa_switch *ds)

No need for inline. Gcc will automatically inline it, if it thinks it
is small enough.

OK, I will respin this without the inline keyword then.

quoted

+{
+	struct mv88e6xxx_priv_state *ps = ds_to_priv(ds);
+
+	if (unlikely(!mutex_is_locked(&ps->smi_mutex))) {
+		dev_err(ds->master_dev, "SMI lock not held!\n");
+		dump_stack();
+	}
+}
+

quoted

-/* Must be called with SMI mutex held */
 static int _mv88e6xxx_reg_read(struct dsa_switch *ds, int addr, int reg)
 {
-	struct mii_bus *bus = dsa_host_dev_to_mii_bus(ds->master_dev);
+	struct mii_bus *bus;
 	int ret;
 
+	assert_smi_lock(ds);
+
+	bus = dsa_host_dev_to_mii_bus(ds->master_dev);

Is this change of when bus is assigned actually required?

No, but I found not necessary to issue this "mdio_bus" lookup if the
lock is not held (see net/dsa/dsa.c:555). Do you prefer not to do that?

Also are you OK with removing all the "Must be called with..." comments,
which I found not necessary too (some function have this comment, some
others don't).

Thanks,
-v